ReviewArticle AReviewonSuperplasticFormationBehaviorofAlAlloysdownloads.hindawi.com/journals/amse/2018/7606140.pdf · deformation.elargerthevalueofstrainratesensitivity is, the greater

Review ArticleA Review on Superplastic Formation Behavior of Al Alloys

Xiao-guo Wang12 Qiu-shu Li 1 Rui-rui Wu1 Xiao-yuan Zhang2 and Liyun Ma3

1School of Materials Science and Engineering Taiyuan University of Science and Technology Taiyuan 030024 China2Department of Mechanical and Electrical Engineering College of Information Shanxi Agricultural UniversityTaigu 030800 China3Department of Mining Engineering Luliang University Lishi 033000 China

Correspondence should be addressed to Qiu-shu Li liqiushutyusteducn

Received 27 March 2018 Revised 27 June 2018 Accepted 16 July 2018 Published 27 September 2018

Academic Editor Guru P Dinda

Copyright copy 2018 Xiao-guo Wang et al is is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Superplastic formation technology is considered to be an effective and promising method to conquer formation difficulties of Alalloys especially thin-walled or complex structure In this paper fundamentals of superplastic deformation of Al alloys aresummarized and the superplastic deformation behaviors of main kinds of Al alloys are summarized and compared including Al-Mg alloys Al-Li alloys and Al-Zn-Mg alloys as well as aluminum matrix composites en the superplastic deformationmechanism for different Al alloys is thoroughly discussed Last but not the least the factors affecting the superplastic deformationprocess are fully analyzed

1 Introduction

11 Superplasticity of Materials Generally speaking su-perplasticity [1ndash6] is a characteristic of some materials withequiaxed and fine grains when they are deformed in tensionat relatively high temperature ((05ndash07)Tm) and low strainrate [7 8] which has been discovered in various materialsRemarkable elongation is a notable symbol of superplas-ticity for example SnndashBi eutectic alloys [9] under super-plastic tensile tests exhibiting outstanding elongation asmuch as 1950 e superplastic elongations of main Alalloys can vary from 200 to 2000 and the elongation ofsome superplastic materials can be up to 8000 e su-perplastic characteristics of materials tremendously improvetheir formability with reduced deformation resistance andviscoussemiviscous flow during plastic deformation par-ticularly for complicated structure components

It is well acknowledged that strain hardening occursduring plastic deformation of which the constitutiveequation [10] is affected by strain-hardening exponent nas shown in Equation (1) e constitutive equation ofsuperplastic deformation at relatively low temperatureabides to viscoplastic Equation (2) proposed by Rossardwhich indicates that the process combines strain hardening

with strain rate hardening e constitutive equation ofsuperplastic deformation at relatively high temperature actsup to flow stress Equation (3) proposed by Backofen et alimplying that the process is mainly manipulated by strainrate sensitivity exponent m

σ Kεn (1)

σ Kεn_εm

(2)

σ K_εm (3)

where σ is the true stress ε is the true strain _ε is the strainrate n is the strain-hardening exponent m is the strain ratesensitivity and k is a parameter for material

12 Superplastic Formability of Al Alloys Because of theirlow density and high specific strength combined with ex-ceptional corrosion resistance Al [11ndash14] are the mostwidely utilized alloys in aerospace automobiles industrymechanical manufacturing marine business and chemicalindustry Superplastic forming technology (SFT) which candramatically decrease flowresidual stress and improveformation quality has been commonly used to manufacture

HindawiAdvances in Materials Science and EngineeringVolume 2018 Article ID 7606140 17 pageshttpsdoiorg10115520187606140

complex shapes in sheet or tube e Al alloys used arecapable of achieving equivalent thickness strains in excess of300 at low strain rates Companies like Superform andAlcoa have successfully applied SFT to produce Al alloyautomobile parts (decklid fenders door inners and brakedisk) with 50 weight saving [15] In 1991 8090 Al alloyswere used to produce military aircraft doors by SFT with23 weight reduction and 68 cost reduction

To enhance the superplastic formability of Al alloys it isnecessary to make the alloys to go through several advancedforming technologies such as flake powder metallurgy [16]and cryo-deformation [17ndash20] as well as severe plasticdeformation (SPD) [21] including friction stir processing(FSP) [22ndash28] equal-channel angular pressing (ECAP)[29ndash35] high-pressure torsion (HTP) [36] accumulative rollbonding (ARB) [37] multiaxial alternative forging (MAF)[38] and repetitive corrugation and straightening (RCS)[39 40] After SPD process ultrafine grain high super-plasticity and low flow stress are available for Al alloys Yetdue to high cost additionally required technologies mayhold back the direct and full commercial application of SPDtechnology Meanwhile more and more energy and re-sources are pouring into developing new and convenienthotcold mechanical processing for superplasticity ofvarious Al alloys erefore thermal-mechanical pro-cessing (TMP) [41ndash43] which is mainly based on theprinciples of static recrystallisation [44ndash47] and dynamicrecrystallisation [48 49] is also an important way to de-velop superplasticity of Al alloys

2 FundamentalsofSuperplasticDeformationofAl Alloys

21 Stacking Fault Energy It is well known that Al and Alalloys are with high stacking fault energy (SFE) which isa significant intrinsic material parameter that would changemechanisms and grain refinement during superplastic de-formation In Al and Al alloys recovery is not totally sup-pressed during superplastic deformation Additionallylowering the SFE would promote deformation twinning overdislocation slip and increase dislocation slip-twinning tran-sition temperature [50 51]

22 Strain-HardeningAbility It is clear that strain hardeningis a typical phenomenon in plastic deformation In the pri-mary stage of superplastic deformation flow stress rapidlyrises with flow strain due to appearance of massive defects(vacanciesdislocationstwinning) As the process goes onstrain softening due to recoveryrecrystallisationcross slipstarts to offset or partially offset the increase of flow stressuntil there is a dynamic balance between the hardening andsoftening processes namely steady stage of superplasticdeformation e strain-hardening ability is strongly de-pendant on temperature and strain rate of superplastic de-formation as shown in Figure 1e true stress increases withincrease in strain rate and decrease in temperature which isexplained in Section 42

23 SuperplasticDeformationBehavior After rolling or SPDAl alloys consist of banded microstructure with subgrainboundaries (SGBs) and low-angle boundaries (LABs) Fol-lowing homogenization annealing Al alloys are recrystallisedand themicrostructure combined with equiaxed recrystallisedgrains with weakened banded grains is formed beforesuperplastic tensile tests e early stage of superplastic de-formation of Al alloys is usually accompanied with staticdynamic grain growth and anisotropic grain elongation Itshould be noticed that grains are more elongated in the tensiledirection than in the transverse direction [53 54] Yet thestaticdynamic grain growth is closely related to the distri-bution of intermetallic precipitates which is fully discussed inSection 42 With the increase in strain the previous mi-crostructure is replaced by a more equiaxed and uniformgrain structure and the banded grains are vanished

24 Crystallographic Texture Crystallographic texture isa preferred orientation structure of grains in ploycrystallinematerials

Being subjected to the formation process (casting rollingrecrystallisation and heat treatment) Al and Al alloys typicalFCC ploycrystalline materials would produce correspondingtexture e main crystallographic texture components inFCC metals are listed in Table 1

Prior to superplastic deformation the microtexture ofrolledSPD Al alloys is of a strong brass texture [17 55]which is a dominant plane strain hot deformation texture forAl alloys After homogenization annealing for proper periodAl alloys exhibit cube near cube rotated cube or decreasedbrass component As the strain of superplastic deformationincreases a randomization of the microtexture happensalong with the increase inmisoriented boundaries thereforethe alloys exhibit a very weak texture component as cubenear cube rotated cube or decreased brass componentFigure 2 shows ODFs representative sections of Al-Zn-Mg-025Sc-010Zr during superplastic deformation In sum-mary the overall texture intensity of Al alloys is substantiallyreduced following superplastic deformation and no neworientation is developed

25 Strain Rate Sensitivity (m) and Deformation ActivationEnergy (Q) Usually superplastic deformation can be de-scribed by an equation for power-law creep in the followingform

_ε AD0Gb

RT

b

d1113888 1113889

p σG

1113874 11138751m

exp minusQ

RT1113874 1113875 (4)

where _ε the is strain rate Q is the activation energy of anappropriate diffusion process A and p are the empiricalmaterial constants G is the shear modulus b is the Burgersvector R is the gas constant T is the absolute temperatureD0 is the frequency factor andm is the strain rate sensitivityexponent (1m is the stress exponent n n 1m)

Strain rate sensitivity (m) is a critical parameter forsuperplastic deformation as its value characterizes theability of an alloy to resist necking spread during

2 Advances in Materials Science and Engineering

deformation e larger the value of strain rate sensitivityis the greater the superplastic elongation will be Addi-tionally it should be aware that m constantly varies duringsuperplastic deformation According to Equation (3) afterlogarithmic transformation strain rate sensitivity can bestated as

m z ln σz log _ε

11138681113868111386811138681113868111386811138681113868T (5)

Normally the varying value of the strain rate sensitivityindicates different mechanisms of superplastic deforma-tion When the value of the strain rate sensitivity is around03 the main mechanism of superplastic deformation of Alalloys is GBS accompanied with other accommodationmechanisms (Section 41) When the value of the strain rate

sensitivity is around 05 the dominant mechanism of su-perplastic deformation of Al alloys is GBS With increasingvalue of strain rate sensitivity GBS gradually becomes themain mechanism of superplastic deformation of Al alloysand is responsible for the majority part of superplasticdeformation of Al alloys

During plastic deformation of metals deformation acti-vation energy Q represents the energy required for thetransition atoms in each mole to jump across the barrierEssentially superplastic deformation is a thermal activationprocess Equation (6) is applied to calculate the activationenergy (Q) which is a critical dynamic parameter to indicatethe level of difficulty of plastic deformation of materials atrelatively high temperature e values of the activationenergy (Q) for different deformation mechanisms are dif-ferent During superplastic deformation the value ofQ for thedislocation pipe diffusion in aluminum is 82 kJmol the valueof the grain-boundary sliding is 84 kJmol and the value oflattice self-diffusion of pure aluminum is 142 kJmol

Q R

m

z ln σz(1T)

1113868111386811138681113868111386811138681113868_ε (6)

where R is the gas constant m is the strain rate sensitivity σis the flow stress and T is the absolute temperature

Average values of m and Q during superplastic de-formation of different aluminum alloys are listed in Table 2

True

stre

ss (M

Pa) 25

20

15

10

5

30

00 04 08 12 16 20 24True strain

ε = 00003sndash1 ε = 0003sndash1


(a)Tr

ue st

ress

(MPa

)

True strain00 04 08 12 16 20 24

25

20

15

10

5

30



(b)

True

stre

ss (M

Pa)

True strain00 04 08 12 16 20 24

25

20

15

10

5

30



(c)

True

stre

ss (M

Pa)

True strain



00 04 08 12 16 20 24

25

20

15

10

5

30

(d)

True

stre

ss (M

Pa)

True strain00 04 08 12 16 20 24

25

20

15

10

5

30



(e)

Figure 1 True stress-true strain curves of 7B04 Al alloy after superplastic deformation under different parameters (a) 470degC (b) 485degC (c)500degC (d) 515degC (e) 530degC [52]

Table 1 Main texture components in FCC metals

Texture hkl ltuvwgt Φ1 (deg) Φ (deg) Φ2 (deg)Cube 0 0 1 lt1 0 0gt 00 0 0Rotated cube 0 0 1 lt1 1 0gt 45 0 0Copper 1 1 2 lt1 1 1gt 90 35 45Brass 0 1 1 lt2 1 1gt 35 45 0Goss 0 1 1 lt1 0 0gt 0 45 0S 1 2 3 lt6 3 4gt 59 37 63R 1 2 4 lt2 1 1gt 57 29 63

Advances in Materials Science and Engineering 3

0deg

65deg

45degMax = 32959330001639981494050201210000497Min = ndash2941

(a)

65deg

0deg 45degMax = 19924330001639981494050201210000497Min = ndash2193

(b)

65deg


(c)

65deg

0deg 45degMax = 2151330001639981494050201210000497Min = 0230

(d)

Figure 2 ODFs representative sections of the Al-Zn-Mg-025Sc-010Zr alloy deformed at 500degC and 1times 10minus2middotsminus1 after interrupting thetensile test at dishyerent strains (a) ε 0 (b) ε 069 (c) ε 110 (d) ε 240 [42]

Table 2 Reference data to illustrate range and average values of m and Q during superplastic deformation

Alloy type T (degC) Strain rate (sminus1) M Q (kJmol) Reference

Al-Mg-Sc-Zr 450ndash525 167times10minus3ndash1times 10minus1 036ndash042039

90ndash126107 [43]

Al-Zn-Mg-Sc-Zr 450ndash500 1times 10minus3ndash1times 10minus1 035ndash040037

838ndash850845 [42]

Al-Zn-Mg-Sc 450ndash500 1times 10minus3ndash1times 10minus2 046ndash051050

838ndash85685 [56]

Al-Mg-Sc-Zr 425ndash500 1times 10minus3ndash1times 10minus1 035ndash053043

93269ndash177517143762 [57]

Al-Mg-Li 430ndash570 5times10minus4ndash1times 10minus3 041ndash085061 mdash [58]

Al3Ti2024Al 450ndash540 015ndash15 mdash 206 [59]


3 The Superplastic Behaviors of Al Alloys

31 Al-MgAlloys Ye et al [58 60ndash67] developed a thermal-mechanical process to produce fine-grained Al-Mg-Sialloy plates with the chemical composition of Al-52Mg-21Li-012Zr(wt) for superplasticity research euniaxial tensile tests were conducted at initial strain ratesranging from 001 to 00005s in the temperature intervalof 450degCndash570degC It turned out that great elongations of580ndash915 were obtained at 510degCndash540degC and initial strainrate between 0001s and 00005s in which the optimalelongation of about 915 occurred at a temperature of 525degCand an initial strain rate of 0001s

Mikhaylovskaya et al [68] put emphasis on the differentsuperplastic deformation behaviors of two fine-grainedAA5083 alloys with and without chromium content atelevated temperature from 500degC to 560degC and constantstrain rates of 00005s 0001s and 0002s e sigmoidalshape of the stress-strain rate curves obtained for both alloysimply that they were subjected to superplastic deformation

Duan et al [41] studied the superplasticity of Al-Mg-015Sc-010Zr alloy using a simple thermal-mechanicalprocessing eir work revealed that the cold rolled alloysheet exhibited excellent superplasticity (elongation ofge800) at a temperature range of 450degCndash500degC and a highstrain rate range of 001ndash01s A maximum elongation of1579 was achieved at 475degC and a high strain rate of 005s

Xu et al [69] performed a research on high strain ratesuperplasticity of an Al-61Mg-025Sc-01Zr (wt) alloy byoriginal asymmetrical rolling technology e alloy sheetswere subjected to both plane strain deformation and ad-ditional shear component along the rolling direction si-multaneously owing to the different circumferentialvelocities of the two rotary rolls e studied alloy exhibitedfantastic superplasticity (elongation gt1000) at the tem-perature interval of 450degCndash500degC and relatively high strainrates ranging from 001s to 025s e highest ductility of3200 is achieved at 500degC and 005s Compared with thesame materials produced by traditional rolling asymmet-rical rolling technology can increase the optimum strain rateup to 10 times

Li et al [43] dealt with the superplastic behavior of an Al-58Mg-04Mn-025Sc-01Zr (wt) alloy at the temperatureinterval of 450degCndash525degC and strain rates ranging from000167s to 01s Experimental results showed that thealloys exhibited nice elongation ranging from 230 to740 and the maximum elongation of 740was achieved at500degC and the initial strain rate of 000667s

32 Al-Li Alloys Xinming Zhang et al [70ndash76] did super-plastic investigation on 2A97 Al-Li alloy at the temperaturerange of 480degCndash490degC and strain rates of 0001ndash00025seresults indicated that the alloy exhibited promising elon-gation ranging from 600 to 850 and the highest elon-gation of 850 was achieved at 490degC and the initial strainrate of 0002s

Zhang et al [55] conducted superplastic investigation on5A90 Al-Li alloy at the temperature range of 450degCndash500degC

and strain rate of 00003ndash00018s e results indicated thatthe alloy exhibited promising elongation ranging from 310to 1050 and the greatest elongation of 1050was achievedat 475degC and the initial strain rate of 00008s

33 Al-Zn-Mg Alloys Wang et al [77ndash86] performed su-perplastic investigation on the friction stir processed (FSP)Al-Zn-Mg-Cu alloy at the temperature of 500degCndash535degC anda high strain rate of 001s e results proved that the FSPAl-Zn-Mg-Cu alloy possesses excellent thermal stability evenup to incipient melting temperature furthermore a highestelongation of 3250 was obtained at 535degC and 001s

Mikhaylovskaya et al [87] compared the superplasticdeformation behavior of two aluminum AA7XXX alloyswith Sc and Zr additions distinguished by the presence andabsence of coarse eutectic Al9FeNi particles e experi-mental results were that the alloy with Sc(01) and Zr(02) additions and eutectic Al9FeNi particles (a size of18 μm and a volume fraction of 0085) exhibits high su-perplasticity (elongation of 300ndash915) at the temperatureinterval of 400degCndash500degC and strain rates ranging from0005s to 001s e highest ductility of 915 is achieved at480degC and 001s On the contrary the alloy with same Sc(01) and Zr(02) additions and without Al9FeNi particlesdid not elongate more than 340 and there is no super-plasticity at high strain rates (more than 001s)

e superplastic performances of the abovementionedaluminum alloys are listed in Table 3

34 Aluminum Matrix Composites A great number of re-searchers [90 91] have been constantly focusing on de-veloping high strain rate and low temperature superplasticformation technology for aluminummatrix composites emost recent works about superplasticity of aluminummatrixcomposites are listed in Table 4

4 Discussion

41 Mechanisms of Superplastic Deformation Enormousefforts and researches have been done on what is the exactmechanism of superplastic deformation yet there is nota unified conclusion

Generally speaking superplastic deformation is mainlycontrolled by three mechanisms grain-boundary sliding(GBS) dislocation slipcreep and diffusion creep or directionaldiffusional flow [53] Meanwhile superplastic deformation isaccompanied by various processes for instance grain-boundary migrations and staticdynamic grain growth grainrotation [80 99] recovery recrystallisation and polygonisation[87 100 101] It is commonly accepted that GBS at low strainrates and creep by glide plus climb also named slip creep athigh strain rates are the dominant controlling mechanisms thatoperate during high-temperature deformation of fine-grainedmetallic materials [102ndash104] e contribution of GBS in thetotal strain varies with different Al alloys

e work of Duan [105] Liu [106] and Cao [107]showed that GBS is a predominant mechanism of super-plastic deformation of Al-Zn-Mg-Sc(Zr) alloys Bate [108]


concluded that the major superplastic deformation mech-anism of Al-6Cu-04Zr alloy may be an intragranular dis-location slip Katsas [109] considered that dynamicrecrystallisation process results in the superplastic de-formation of Al-1Zr alloy Sotoudeh [110] and Bricknell[111] believed that diffusion creep is the main superplasticitymechanism of ldquosupral typerdquo alloys with banded micro-structure del Valle et al [112] concluded that Al alloys thatwere composed of fine-equiaxed grains at the start of thesuperplastic test deformed mainly by GBS at low strain ratewith only small evidence of dislocation activity and slip creepwas the controlling mechanism at high strain rate super-plastic deformation e research of Wang et al [86] in-dicated that the presence of a liquid phase because highexperimental temperature plays a vital role in the extraor-dinary elongation of the alloy by relaxing the stress con-centration and suppressing the the appearance of cavitiesduring deformation Jiao [59] also supported that a certainamount of liquid phase during superplastic deformation canproperly enhance the superplasticity of aluminum alloysMeanwhile Johannes and Mishra [113] concluded that fiber(whisker) formation (Figure 3) was the evidence of theexistence of liquid phases along grain boundaries Fur-thermore Duan et al [56] thought the existence of fiber asan indirect evidence for GBS

Commonly fine and equiaxed grains are typical fea-tures of superplastic materials It is fully established bya great number of theories and researches that grain-boundary sliding is the dominant reason that fine-grainedmaterials are able to develop superplastic deformation

During deformation materials migration and grain-boundary sliding happen simultaneously in order to assureintergranular accommodation Moreover it is necessary foranother mechanism to accommodate stress concentrationresulting from GBS ere are two main accommodationmechanisms for GBS diffusion creep and dislocation sliding

After a thorough research Ashby and Verrall proposedthe classic mechanism theory of GBS with diffusion creep forsuperplastic deformation the theoretical model of which isshown in Figure 4 e AshbyndashVerrall model (Figure 3)interprets how the equiaxed grains move by means of GBSough the shape of grains stay the same after slidingtheoverall morphology changes which is in agreement withmacroelongation Moreover Ashby and Verrall explainedthat the strain difference between the initial and final cir-cumstances is accommodated by grain-boundary diffusionand volume diffusion as well as the ability of grain-boundarydiffusion is much stronger than that of volume diffusion

Currently there are three models for theories of grain-boundary sliding accommodated by dislocation slidingwhich are introduced in Table 5

Additionally it is considered that the mechanism ofsuperplastic deformation for Al alloys is related to the mi-crostructure status of the alloys prior to the deformationAfter TMP there are two ways to obtain fine grains for thealloys which would result in different mechanisms of su-perplastic deformation On one hand if the thermal-mechanically treated alloys are subjected to recrystallisationannealing treatment the main deformation mechanism ofsuperplastically deformed alloys is concurrently controlled by

Table 3 Deformation conditions of optimal superplastic elongation of Al alloys

Al alloys (wt) Temperature (degC) Strain rate (sminus1) Elongation () ReferenceAl-52Mg-21Li-012Zr 525 0001 915 [58]Al-Mg-015Sc-010Zr 475 005 1579 [41]Al-61Mg-025Sc-01Zr 500 005 3200 [69]Al-58Mg-04Mn-025Sc-01Zr 500 000667 740 [43]Al-53Mg-21Li-011Zr 475 00008 1050 [55]Al-5Mg-02Sc 520 0056 2300 [88]Al-3Mg-02Sc 400 0033 2280 [89]Al-38Cu-14Li(2A97) 490 0002 850 [76]Al-585Zn-256Mg-189Cu 535 001 3250 [86]Al-6Zn-23Mg-17Cu(7B04) 530 00003 1105 [52]Al-56Zn-22Mg-15Cu(7475) 515 00005 590 [46]Al-541Zn-19Mg-025Sc-01Zr 500 001 1523 [76]Al-536Zn-19Mg-01Sc-01Zr 500 0005 1050 [56]Al-54Zn-2Mg-025Sc-01Zr 200 001 539 [57]

Table 4 Deformation conditions of optimal superplastic elongation of aluminum matrix composites

Composites Temperature (degC) Strain rate (sminus1) Elongation () Reference20wtSi3N4P5052 545 0001 700 [92]10wtSiCP2024 480 0001 345 [93]20wtSi3N4P2124 510 004 840 [94]15wtSiCPIN9021 550 0005 610 [95]178wtSiCP2124 490 0083 425 [96]15wtSiCP6A02 560 000089 250 [97]12wtSiCP5052 550 00011 405 [98]5wtAl3Ti2024 510 015 640 [59]


both grain-boundary sliding (GBS) and accompanied ac-commodation mechanism which include dislocation motion[116ndash118] creep diffusion [119] and liquid phase [86] aimingto relax the stress concentration On the other hand when thethermal-mechanically treated alloys directly experience su-perplastic deformation during the primary stage of de-formation the mechanism is controlled by deformation-induced continuous recystallisation (DICR) due to the oc-currence of dynamic recrystallisation Subsequently the su-perplastic deformation mechanism is similar to staticrecrystallisation after dynamic recrystallisation is completed

42 Factors Affecting Superplastic Deformation Behavior

421 Temperature of Superplastic DeformationFundamentally speaking superplasticity is a thermally ac-tivated phenomenon therefore the deformation tempera-ture is a crucial factor It is commonly accepted that there isa basic requirement for the Al alloys to exhibit superplas-ticity which is that the deformation temperature shall bemore than 05Tm (melting temperature) As the temperaturekeeps rising the viscous forces within grain boundariesgradually reduce and grain boundaries become more andmore unstable As a result the grain boundary begins to slidewith relative ease which makes the tensile test sample toshow better elongation However if the temperature is toohigh grain boundaries are excessively softened and grain-boundary binding force dramatically decreases which leadto less elongations It can be seen from Figure 5 that thesuperplastic elongations are intensively changed with dif-ferent temperatures of superplastic deformation and there isan optimal temperature for each kind of aluminum alloy

Zhang et al [52] found out that superplastic property ofAl alloys started to decline and became insensitive to de-formation temperature when the alloys were superplasticallydeformed at relatively high strain rates

422 Strain Rates of Superplastic Deformation Besidesdeformation temperature stain rates also could notablyinfluence the superplasticity of Al alloys As shown inEquation (3) the true stress σ is highly dependent on thestrain rate _ε so it also means that the superplastic de-formation process of Al alloys is significantly affected by thestrain rate

Researches [120 121] indicate that one precondition ofsuperplasticity is that the stain rates should be in the range of10minus4ndash10minus1s Figure 6 shows the correlation between su-perplastic elongation and varying initial strain rates atdifferent temperatures of different Al alloys It can be seenthat relatively low strain rates are in favor of better super-plasticity Deformed at lower initial strain rates the Al alloysexhibit an extended strain-hardening phenomenon anddecreased strain-hardening rates due to dislocation re-laxation triggered by accommodation mechanisms of GBSAt the same time the microstructure of Al alloys after su-perplastic deformation is partially determined by strainrates Low strain rates could result in coarseness of themicrostructure ascribed to recovery and recrystallisationprocesses Better superplasticity resulting from relatively lowstrain rates comes at a price of great amount of time whichstrongly restricts further application of superplastic de-formation of Al alloys Consequently high strain rate su-perplasticity (HSRSP) [122ndash127] which can not onlydramatically reduce the consuming time but also develophigh superplasticity is attracting more and more attention

423 Precipitates Particles Prior to superplastic de-formation particles with different size locations and shapesare distributed in the grains and at the boundaries whichwill play a very important role during superplasticity

By adding a few amount of trace element high density ofcoherent fine precipitates (Al3(ZrSc) sim30 nm [128ndash131]Al6(MnCr) 38plusmn 7 nm [68]) are formed and dispersedboth at grain boundaries and within the grain interiorswhich will strongly retard the grain growth during

10 μm

Figure 3 SEM image of fracture morphology of superplastically deformed Al alloys [41 42 57]

TT

T

T

σ

σ

Figure 4 e AshbyndashVerrall theoretical model for superplasticdeformation (a) Initial (b) Intermediate (c) Final


recrystallisation and inhibit the movement of grainboundaries subgrain boundaries and dislocation by theZener pinning eshyect (Figure 7) Furthermore the stability of

cavity can be partially attributed to additional interfacialenergy of Al3(ZrSc) particles

Besides nanoscale particles there are also existence ofother coarse particles (Al9FeNi sim18 μm Figure 8 [87]) thatashyect superplastic deformation ese coarse particles canform extensive deformation zones during rolling or SPDprocess which can accelerate nucleation at preheating and atsuperplastic deformation ascribed to particles stimulatednucleation (PSN) and lead to grain renement

In addition the presence of particle-depleted zones(PDZs) associated with dishyusion creep is often detected in theAl alloys with uniform distribution of nanosized particlesduring superplastic deformatione PDZ is often consideredto facilitate the total elongation of Al alloys during SPF

424 ermal-Mechanical Processing As stated in Section12 thermal-mechanical processing plays a vital pole for Alalloys to obtain superplasticity Even the alloys with ex-perimentally approximate composition such as Al-58Mg-04Mn-025Sc-010Zr [43] and Al-610Mg-03Mn-025Sc-010Zr [69] may exhibit superplasticity with huge dishyer-ence simply owing to distinguished thermal-mechanicalprocesses Both the elongations of the Al-58Mg-04Mn-025Sc-010Zr and Al-610Mg-03Mn-025Sc-010Zr alloyssample were tested at the temperatures ranging from 450degCto 475degC and at strain rates of 0005s to 01s however

Table 5 ree models for theories of grain-boundary sliding accommodated by dislocation sliding

Models Schematic illustration of the mechanismof superplasticity Introduction of the models

BallndashHutchisonmodel [114]

Stressconcentration

Pling upEasy grain boundary

sliding plane

During deformation grain boundaries are properly alignedand slide as groups When the sliding is blocked by othergrains the local stresses would result in dislocation in the

blocking grain piling up at the opposite grain boundary untilthe back stress stops further generation of dislocation epiled up dislocations could climb into and along the grainboundary us grain-boundary sliding which is governed bythe kinetics of climb along grain boundary to annihilationareas is feasible due to the constant replacement of the

dislocation

Mukherjeemodel [115] Pling up

Slidingdirection

Ledgee model elaborates dislocation accommodated slidingmechanism of single grain Dislocations are generated atscraggy surfaces of grain boundaries e alignment

mechanism of the generated dislocations is the same as that ofthe BallndashHutchison model

Gifkinsmodel [116]

Grain A

Grain C

Grain B

Newdislocation

Slidingdirection

Gifkins described grain-boundary sliding and accommodationprocess as grain-boundary dislocation motion and proposedthe core-mantle model Grain-boundary sliding around grain

triple junctions is accommodated by generation of newdislocation and their climbing along the boundaries

Dislocation motion is constrained to occur at grain boundaryand mantle area rather than in the core of grain According tothe model grains are able to slide by switching places in three-

dimensional space

300

400

500

600

700

800

900

1000

Supe

rpla

stic e

long

atio

n (

)

Tensile test temperature (degC)420 440 460 480 500 520 540

Alloy typeAl-Li-Cu

Strain rate (sndash1)0001001

0006670001015

Al-Mg-Sc-ZrAl-Mg-Si5wtAl3Ti2024

Al-Zn-Mg-Zr-Sc

Figure 5 Variation of superplastic elongations of dishyerent Alalloys with initial strain rates at various temperatures


1200

1000

800

600

400

200

0

Elon

gatio

n (

)

10ndash3 10ndash2

Strain rate (sndash1)10ndash1

475degC 550degC450degC

500degC

525degC

850

800

750

700

650

Supe

rpla

stic e

long

atio

n (

)

Initial strain rate (sndash1)

600

550

50000012 00018 00024

480degC470degC

490degC

00 03 06 09 12 15

Elon

gatio

n (

)

10ndash3 10ndash2

Strain rate (sndash1)480degC

Supe

rpla

stic e

long

atio

n (

)


5001000

800

600

400

200

450

400

350

300

250

200

150

450degC480degC

525degC540degC

510degC

Figure 6 Variation of superplastic elongations of dishyerent Al alloys with varying initial strain rates at various temperatures (a) Al-Zn-Mg-Sc-Zr [56] (b) Al-Li-Cu (c) Al-Mg-Si [47] (d) 5wtAl3Ti2024

(a) (b)

Figure 7 Continued


subjected to different thermal-mechanical processes simplerolling and asymmetrical rolling respectively (please check[43 69] for details)

Figure 9 shows the comparison of maximum elongationsof the two Al-Mg-Mn-Sc-Zr alloys under 4 tested temper-atures of all tested stain rates It is well established that theasymmetrical rolled alloy e maximum elongations ofasymmetrical rolled Al-Mg-Mn-Sc-Zr alloy is at least 31times that of simple rolled Al-Mg-Mn-Sc-Zr alloy

43 Recovery and Recrystallisation As described in Section22 recovery and recrystallisation are of great importance instructural softening mechanism of Al alloys Owing to highSFE of Al alloys dynamic recovery is even more importantto the softening process erefore the following sectionsillustrate the softening process caused by recovery andrecrystallisation in detail

431 Dynamic Recovery High density of defects (vacan-cies and dislocations) is generated and accumulated in themicrostructure of plastic deformed Al alloys High SFEand solute strengthening effect work together to make Alalloys undergo dynamic recovery mechanisms whichinclude (a) annihilation resulting in neutralization ofdislocation dipoles and reduction in dislocation density

(b) polygonisation which involves systemic organiza-tion of randomly oriented dislocation into more stablemicrostructural elements called cells and (c) prolifera-tion of cells into fully developed subgrains [18] Because

(c) (d)

Figure 7 TEM microstructures of superplastically deformed Al-Zn-Mg-Sc-Zr alloy [42 56]

(a) (b)

Figure 8 TEM microstructures of Al-Zn-Mg-Sc-Zr alloy (a) 20 minutes annealed at 480degC (b) strain of 125 [87]

440

500

1000

1500

2000

2500

3000

3500

460 480Tensile test temperature (degC)

Max

imum

elon

gatio

n (

)

500 520 540

Simple rolled Al-Mg-Sc-ZrAsymmetrical rolled Al-Mg-Sc-Zr

Figure 9 Comparison of maximum elongations of the two Al-Mg-Mn-Sc-Zr alloys under 4 tested temperatures of all tested stainrates


of work hardening tangled microstructure is formedand transformed into an ordered one by rearrangementof dislocations into micronscale entities called cellsDensly tangled dislocations are located along theboundaries of the cells while less dislocations are foundwithin the cell interiors resulting from annihilation of theinternal dislocations Subsequently the cell boundariesturn into structured subgrain boundaries with highermisorientation

432 Deformation-Induced Continuous RecrystallisationIf the alloy sheets subjected to severe rollingSPD processare directly superplastically deformed without staticrecrystallisaion annealing it is the brous structure ratherthan equiaxed grain structure that participate in the su-perplastic deformation us there are two stages existingduring superplastic deformation according to structuretransformation e initial microstructure of the de-formed Al alloys consists of a large amount of LABswhich are not favorable for GBS because of their lowmisorientations while it is well proved that HABs are

desired microstructure for superplastic copyow by GBS[132 133] In the rst stage when the superplastic de-formation induced continuous recrystallisation initialbrous grain structures typical LABs along the rollingdirection gradually shift into equiaxed grains HABs keepincreasing until the transformation of grains is completed(Figure 10) grain orientation is gradually randomized(Figure 11) and texture is weakened After dynamicrecrystallisation is nished the second stage of super-plastic deformation is mainly controlled by grain-boundarysliding

5 Existing Challenges and Limitations

In spite of the inspiring and exciting research outcomesabout superplastic formation behavior of Al alloys there arestill enormous unknown yet critical territories waiting to befound out and developed

(i) ere are still long way to go to develop a syntheticaltheory to utterly reveal the essence of superplasticityof Al alloys

030

025

020

015

010

005

00010 20 30 40 50 60

Freq

uenc

y

Misorientation angle (degree)

fHABs = 273

(a)

018

014

016

012

010

006

004

008

002

00010 20 30 40 50 60

Freq

uenc

y

fHABs = 435


(b)

000

001

002

003

004

005

006

Freq

uenc

y


fHABs = 759

10 20 30 40 50 60

(c)

10 20 30 40 50 60000

001

002

003

004

005

Freq

uenc

y


fHABs = 988

(d)

Figure 10 Misorientation angle distribution of the Al-Zn-Mg-025Sc-01Zr alloy deformed at 500degC and 1times 10minus2middotsminus1 after interrupting thetensile test at dishyerent strains (a) ε 0 (b) ε 069 (c) ε 110 (d) ε 240 [42]


(ii) To exhibit superplasticity the Al alloys need to meetthe strict microstructure requirements which arefor the alloys to hold equiaxed and fine grains as wellas the ability to recrystallisation

(iii) Superplasticity of Al alloys also holds specific de-formation requests including high temperaturesand low strain rates which obviously limit thefurther industrialized and commercial applicationsof superplastic deformation

(iv) For now the applications of advanced severe plasticdeformation (SPD) technologies which are oftenused to activate superplasticity of Al alloys arebasically limited to scientific research and studyere is no sign to make SPD technologies fullyutilize in commercial process

(v) ere are few researches about combining super-plastic deformation with other forming technolo-gies such as welding and casting to form complex-shaped components

(vi) It is necessary to keep developing Al alloys withexceptional and comprehensive properties in-cluding strength ductility superplastic formationability and stress corrosion resistance so that thepotentials of Al alloys can be fully released

6 Conclusions

In this paper the fundamentals and superplastic deforma-tion behaviors of several series of Al alloys are described and itcan be seen that currently the main different kinds of Al alloysall have exhibited outstanding superplasticity Furthermorethe mechanisms of superplastic deformation are discussedand various theories regarding superplastic mechanism aresummarized and analyzed including theory of grain-boundary sliding with accommodation mechanism anddeformation-induced continuous recrystallisation Mean-while factors that affect superplastic deformation process ofAl alloys are explained in detail including temperatures stainrates and thermal-mechanical process Subsequently twosignificant superplastic deformation parameters of differentAl alloys strain rate sensitivity (m) and deformation acti-vation energy (Q) are compared to help understand therelationship within these two parameters and superplasticdeformation mechanisms Finally the existing challenges andlimitations of current superplastic deformation of Al alloysare properly summarized

Conflicts of Interest

e authors declare that they have no conflicts of interest

(a)

(c)

(b)

(d)

Figure 11 EBSD analyses of the Al-Zn-Mg-025Sc-010Zr alloy deformed at 500degC and 1times 10minus2middotsminus1 after interrupting the tensile test atdifferent strains (a) ε 0 (b) ε 069 (c) ε 110 (d) ε 240 [42]


References

[1] G Giuliano Superplastic Forming of Advanced MetallicMaterials Methods and Applications Elsevier 2011

[2] T Y M Al-Naib and J L Duncan ldquoSuperplastic metalformingrdquo International Journal of Mechanical Sciencesvol 12 no 6 pp 463ndash470 1970

[3] JIS H 7007 Glossary of Terms used in Metallic SuperplasticMaterials Japanese Standards Association Tokyo Japan1995

[4] V N Perevezentsev V V Rybin and V N Chuvilrsquodeevldquoe theory of structural superplasticitymdashIII Boundarymigration and grain growthrdquo Acta Metallurgica et Materi-alia vol 40 pp 907ndash914 1992

[5] A H Chokshi A K Mukherjee and T G LangdonldquoSuperplasticity in advanced materialsrdquo Materials Scienceand Engineering R Reports vol 10 no 6 pp 237ndash2741993

[6] C H Hamilton ldquoSimulation of static and deformation-enhanced grain growth effects on superplastic ductilityrdquoMetallurgical Transactions A vol 20 no 12 pp 2783ndash27921989

[7] P S Bate N Ridley and B Zhang ldquoMechanical behaviourand microstructural evolution in superplastic AlndashLindashMgndashCundashZr AA8090rdquo Acta Materialia vol 55 no 15pp 4995ndash5006 2007

[8] G Sakai Z Horita and T G Langdon ldquoGrain refinementand superplasticity in an aluminum alloy processed by high-pressure torsionrdquo Materials Science and Engineering Avol 393 no 1-2 pp 344ndash351 2005

[9] C E Pearson ldquoViscous properties of extruded eutectic alloysof Pb-Sn and Bi-Snrdquo Journal of Institute Metals vol 54 no 1pp 111ndash123 1934

[10] O Ruano and O D Sherby ldquoOn constitutive equations forvarious diffusion-controlled creep mechanismsrdquo Revue dePhysique Appliquee vol 23 pp 625ndash637 1988

[11] B M Watts M J Stowell B L Baikie and D G E OwenldquoSuperplasticity in Al-Cu-Zr alloys Part 1 material prepa-ration and propertiesrdquo Metal Science vol 10 pp 189ndash1971976

[12] S Mehta P K Sengupta K J L Iyer and K Nair ldquoStudies ofthe superplasticity of high strength aluminium alloyrdquo Alu-minium vol 68 pp 234ndash237 1992

[13] J Xinggang W Qingliing C Jianzhong and M LongxiangldquoA study of the improvementrdquoMetallurgical Transactions Avol 24 no 11 pp 2596-2597 1993

[14] J Xinggang C Janzhong and M Longxiang ldquoA study ofgrain refinement and superplasticity of high strength 7475 Alalloyrdquo ZMetallkd vol 84 pp 216ndash219 1993

[15] M Mabuchia and K Higashib ldquoOn accommodation helpermechanism for superplasticity in metal matrix compositesrdquoActa Materialia vol 47 no 6 pp 1915ndash1922 1999

[16] H Huang G Fan and Z Tan ldquoSuperplastic behavior ofcarbon nanotube reinforced aluminum composites fabri-cated by flake powder metallurgyrdquo Materials Science andEngineering A vol 699 pp 55ndash61 2017

[17] K Arun Babu V Subramanya Sarma and C N AthreyaldquoExperimental verification of grain boundary-sliding con-trolled steady state superplastic flow in both continually andstatically recrystallizing Al alloysrdquo Materials Science andEngineering A vol 657 pp 185ndash196 2016

[18] A Dhal S K Panigrahi and M S Shunmugam ldquoInsightinto the microstructural evolution during cryo-severe plasticdeformation and post-deformation annealing of aluminum

and its alloysrdquo Journal of Alloys and Compounds vol 726pp 1205ndash1219 2017

[19] H P Pu F C Liu and J C Huang ldquoCharacterization andanalysis of low-temperature superplasticity in 8090 Al-Lialloysrdquo Metallurgical and Materials Transactions A vol 26pp 1153ndash1166 1995

[20] F C Liu and Z Y Ma ldquoContribution of grain boundarysliding in low-temperature superplasticity of ultrafine-grained aluminum alloysrdquo Scripta Materialia vol 62no 3 pp 125ndash128 2010

[21] R Valiev ldquoNanostructuring of metals by severe plastic de-formation for advanced propertiesrdquo Nature Materials vol 3no 8 pp 511ndash516 2004

[22] L B Johannes I Charit R S Mishra and R VermaldquoEnhanced superplasticity through friction stir processing incontinuous cast AA5083 aluminumrdquo Materials Science andEngineering A vol 464 pp 351ndash357 2007

[23] I Charit and R S Mishra ldquoEvaluation of microstructure andsuperplasticity in friction stir processed 5083 Al alloyrdquoMaterials Research vol 19 no 11 pp 3329ndash3342 2004

[24] M A Garcıa-Bernal R S Mishra R Verma andD Hernandez-Silva ldquoHigh strain rate superplasticity incontinuous cast AlndashMg alloys prepared via friction stirprocessingrdquo Scripta Materialia vol 60 no 10 pp 850ndash8532009

[25] Z Y Ma and R S Mishra ldquoDevelopment of ultrafine-grained microstructure and low temperature (048 Tm)superplasticity in friction stir processed AlndashMgndashZrrdquo ScriptaMaterialia vol 53 no 1 pp 75ndash80 2005

[26] A Orozco-Caballero M Alvarez-Leal P Hidalgo-Man-rique C MarıaCepeda-Jimenez O Antonio Ruano andF Carrentildeo ldquoGrain size versus microstructural stability in thehigh strain rate superplastic response of a severely frictionstir processed Al-Zn-Mg-Cu alloyrdquo Materials Science andEngineering A vol 680 pp 329ndash337 2017

[27] J A del Valle P Rey D Gesto D Verdera andJ A Jimenez ldquoMechanical properties of ultra-fine grainedAZ91magnesium alloy processed by friction stir processingrdquoMaterials Science and Engineering A vol 628 pp 198ndash2062015

[28] A Orozco-Caballero P Hidalgo-Manrique andC M Cepeda-Jimenez ldquoStrategy for severe friction stirprocessing to obtain acute grain refinement of an AlndashZnndashMgndashCu alloy in three initial precipitation statesrdquo MaterialsCharacterization vol 112 pp 197ndash205 2016

[29] H Akamatsu T Fujinami Z Horita and T G LangdonldquoInfluence of rolling on the superplastic behavior of an Al-Mg-Sc alloy after ECAPrdquo Scripta Materialia vol 44 no 5pp 759ndash764 2001

[30] Z Horita M Furukawa M Nemoto A J Barnes andT G Langdon ldquoSuperplastic forming at high strain ratesafter severe plastic deformationrdquo Acta Materialia vol 48no 14 pp 3633ndash3640 2000

[31] K T Park H J Lee C S Lee W J Nam and D H ShinldquoEnhancement of high strain rate superplastic elongation ofa modified 5154 Al by subsequent rolling after equal channelangular pressingrdquo Scripta Materialia vol 51 no 6pp 479ndash483 2004

[32] R Z Valiev and T G Langdon ldquoPrinciples of equal-channelangular pressing as a processing tool for grain refinementrdquoProgress inMaterials Science vol 51 no 7 pp 881ndash981 2006

[33] R B Figueiredo and T G Langdon ldquoEvaluating the Su-perplastic Flow of a Magnesium AZ31 Alloy Processed by


Equal-Channel Angular Pressingrdquo Metallurgical and Ma-terials Transactions A vol 45 no 8 pp 3197ndash3204 2014

[34] C M Cepeda-Jimenez J M Garcıa-Infanta O A Ruanoand F Carrentildeo ldquoMechanical properties at room temperatureof an AlndashZnndashMgndashCu alloy processed by equal channel an-gular pressingrdquo Journal of Alloys and Compounds vol 509pp 8649ndash8656 2011

[35] C M Cepeda-Jimenez and J M Garcıa-Infanta ldquoInfluenceof Processing Severity During Equal-Channel AngularPressing on the Microstructure of an Al-Zn-Mg-Cu AlloyrdquoMetallurgical and Materials Transactions A vol 43 no 11pp 4224ndash4236 2012

[36] L Jiao Y T Zhao and W Yue ldquoe development of highstrain rate and low temperature superplasticity in aluminummatrix compositesrdquo Materials Review vol 27 pp 119ndash1232013

[37] N Tsuji K Shiotsuki and Y Saito ldquoSuperplasticity of ultra-finegrained alndashmg alloy produced by accumulative roll-bondingrdquoMaterials Transactions JIM vol 40 no 8 pp 765ndash771 1999

[38] M Node M Hirohashi and K Funami ldquoLow temperaturesuperplasticity and its deformation mechanism in grainrefinement of Al-Mg Alloy by multi-axial alternative forg-ingrdquo Materials Transactions vol 44 no 11 pp 2288ndash22972003

[39] Y T Zhu T C Lowe H Jiang et al United States PatentApplication USP6197129 2001

[40] Y T Zhu H Jiang J Y Huang et al ldquoA new route to bulknanostructured metalsrdquo Metallurgical and MaterialsTransactions A vol 32 no 6 pp 1559ndash1562 2001

[41] Y L Duan L Tang Y Deng X W Cao G F Xu andZ M Yin ldquoSuperplastic behavior and microstructure evo-lution of a new Al-Mg-Sc-Zr alloy subjected to a simplethermomechanical processingrdquo Materials Science and En-gineering A vol 669 pp 205ndash217 2016

[42] Y L Duan G F Xu X Y Peng Y Deng Z Li andZ M Yin ldquoEffect of Sc and Zr additions on grain stabilityand superplasticity of the simple thermalndashmechanical pro-cessed AlndashZnndashMg alloy sheetrdquo Materials Science and Engi-neering A vol 648 pp 80ndash91 2015

[43] M Li Q Pan Y Shi X Sun and H Xiang ldquoHigh strain ratesuperplasticity in an AlndashMgndashScndashZr alloy processed viasimple rollingrdquo Materials Science and Engineering Avol 687 pp 298ndash305 2017

[44] X G Jiang Q L Wu J Z Cui et al ldquoA new grain-re-finement process for superplasticity of high-strength 7075aluminum alloyrdquo Journal of Materials Science vol 28pp 6038-6039 1993

[45] D H Shin C S Lee and W Kim ldquoSuperplasticity of fine-grained 7475 Al alloy and a proposed new deformationmechanismrdquo Acta Materialia vol 45 no 12 pp 5195ndash52021997

[46] A Smolej M Gnamus and E Slacek ldquoe influence ofthe thermomechanical processing and forming parameterson superplastic behaviour of the 7475 aluminium alloyrdquoJournal of Materials Processing Technology vol 118 no 1-3pp 397ndash402 2001

[47] L Y Ye X M Zhang D W Zheng et al ldquoSuperplasticbehavior of an AlndashMgndashLi alloyrdquo Journal of Alloys andCompounds vol 487 no 1-2 pp 109ndash115 2009

[48] H P Pu and J C Huang ldquoProcessing routes for inter-transformation between low- and high-temperature 8090AlndashLi superplastic sheetsrdquo Scripta Metallurgica et Materialiavol 33 no 3 pp 383ndash389

[49] J Wadsworth and A R Pelton ldquoSuperplastic behavior ofa powder-source aluminum-lithium based alloyrdquo ScriptaMetallurgica vol 18 no 4 pp 387ndash392 1984

[50] E El-Danaf S R Kalidindi and R G Doherty ldquoInfluence ofgrain size and stacking-fault energy on deformation twin-ning in fcc metalsrdquoMetallurgical and Materials TransactionsA vol 30 no 5 pp 1223ndash1233 1999

[51] A Rohatgi K S Vecchio and G T Gray III ldquoA metallo-graphic and quantitative analysis of the influence of stackingfault energy on shock hardening in Cu and CundashAl alloysrdquoActa Materialia vol 49 pp 427ndash438 2001

[52] N Zhang Y Wang and H Hou ldquoSuperplastic deformationbehavior of 7B04 Al alloyrdquo Journal of Materials Engineeringvol 45 pp 27ndash33 2017

[53] A V Mikhaylovsaya O A Yakovtseva and M N SitkinaldquoComparison between superplastic deformation mecha-nisms at primary and steady stages of the fine grain AA7475aluminium alloyrdquo Materials Science and Engineering Avol 718 pp 277ndash286 2018

[54] M Kh Rabinovich and V G Trifonof ldquoDynamic graingrowth during superplastic deformationrdquo Acta Materialiavol 44 no 5 pp 2073ndash2078 1996

[55] P Zhang L Ye X Zhang G Gu H Jiang and Y WuldquoGrain structure and microtexture evolution during super-plastic deformation of 5A90 Al-Li alloyrdquo Transactions ofNonferrous Metals Society of China vol 24 no 7pp 2088ndash2093 2014

[56] Y Duan G Xu L Zhou and D Xiao ldquoAchieving highsuperplasticity of a traditional thermalndashmechanical pro-cessed non-superplastic AlndashZnndashMg alloy sheet by low Scadditionsrdquo Journal of alloys and compounds vol 638pp 364ndash373 2015

[57] H Xiang Q L Pan X H Yu X Huang X Sun andX D Wang ldquoSuperplasticity behaviors of Al-Zn-Mg-Zrcold-rolled alloy sheet with minor Sc additionrdquo MaterialsScience Engineering A vol 676 pp 128ndash137 2016

[58] L Ye X Zhang and D Zheng ldquoSuperplastic behavior of anAlndashMgndashLi alloyrdquo Journal of alloys and compounds vol 487pp 109ndash115 2009

[59] L Jiao Research on Plastic Deformation Behavior andProperties of In Situ Particulate Reinforced AluminumMatrixComposites Jiangsu University Suzhou China 2014

[60] O Roder T Gysler and G Lutjering ldquoFatigue properties ofAl-Mg alloys with and without scandiumrdquoMaterials Scienceand Engineering A vol 234ndash236 pp 181ndash184 1997

[61] R J Dashwood R Grimes A W Harrison andH M Flower ldquoe Development of a High Strain RateSuperplastic Al-Mg-Zr Alloyrdquo Materials Science Forumvol 357ndash359 pp 339ndash344 2001

[62] R Grimes R J Dashwood A W Harrison andH M Flower ldquoDevelopment of a high strain rate super-plastic AlndashMgndashZr alloyrdquo Materials Science and Technologyvol 16 no 11-12 pp 1334ndash1339 2000

[63] D H Bae and A K Ghosh ldquoGrain size and temperaturedependence of superplastic deformation in an AlndashMg alloyunder isostructural conditionrdquo Acta Materialia vol 48no 6 pp 1207ndash1224 2000

[64] A Smolej D Klobcar B Skaza et al ldquoSuperplasticity of therolled and friction stir processed Alndash45 Mgndash035Scndash015Zralloyrdquo Materials Science and Engineering A vol 590pp 239ndash245 2014

[65] M Furukawa P Berbon and T G Langdon ldquoAge hardeningand the potential for superplasticity in a fine-grained Al-Mg-


Li-Zr alloyrdquo Metallurgical and Materials Transactions Avol 29 no 1 pp 169ndash177 1998

[66] M Furukawa Y Iwahashi Z Horita and M NemotoldquoStructural evolution and the Hall-Petch relationship in anAl-Mg-Li-Zr alloy with ultra-fine grain sizerdquo Acta Materi-alia vol 45 no 11 pp 4751ndash4757 1997

[67] L Man-ping S Shao-chun H J Roven et al ldquoDeformationdefects and electron irradiation effect in nanostructuredAlndashMg alloy processed by severe plastic deformationrdquoTransactions of Nonferrous Metals Society of China vol 22no 8 pp 1810ndash1816 2012

[68] A V Mikhaylovskaya O A Yakovtseva I S Glolovin andA V Pozdniakov ldquoSuperplastic deformation mechanisms infine-grained AlndashMg based alloysrdquo Materials Science andEngineering A vol 627 pp 31ndash41 2015

[69] G Xu X Cao T Zhang Y Duan X Peng and Y DengldquoAchieving high strain rate superplasticity of an Al-Mg-Sc-Zr alloy by a new asymmetrical rolling technologyrdquoMaterials Science and Engineering A vol 672 pp 98ndash1072016

[70] R J Rioja and J Liu ldquoe Evolution of Al-Li base productsfor aerospace and space applicationsrdquo Metallurgical andMaterials Transactions A vol 43 no 9 pp 3325ndash3337 2012

[71] H Yin H Li X Su and D Huang ldquoProcessing mapsand microstructural evolution of isothermal compressedAlndashCundashLi alloyrdquo Materials Science and Engineering Avol 586 pp 115ndash122 2013

[72] Y Lin and Z Zheng ldquoMicrostructural evolution of 2099 Al Lialloy during friction stir welding processrdquo Materials Char-acterization vol 123 pp 307ndash314 2017

[73] Y Lin Z Zheng S Li X Kong and Y Han ldquoMicro-structures and properties of 2099 Al-Li alloyrdquo MaterialsCharacterization vol 84 pp 88ndash99 2013

[74] A A Mazilkin and M M Myshlyaev ldquoMicrostructureand thermal stabilityof superplastic aluminiummdashlithiumalloy after severe plastic deformationrdquo Journal of MaterialsScience vol 41 no 12 pp 3767ndash3772 2006

[75] R Kaibyshev K Shipilova and F Musin ldquoAchieving highstrain rate superplasticity in an AlndashLindashMg alloy throughequal channel angular extrusionrdquo Materials Science andTechnology vol 21 no 4 pp 408ndash418 2005

[76] X Zhang L Xie L Ye and Panzhang ldquoEffect of agingtreatment on grain refinement and superplasticity of 2A97aluminum-lithium alloyrdquo Heat Treatment of Metals vol 39pp 88ndash92 2014

[77] M Taheri-Mandarjani A Zarei-Hanzaki and H R AbedildquoHot ductility behavior of an extruded 7075 aluminum al-loyrdquo Materials Science and Engineering A vol 637pp 107ndash122 2015

[78] K Ma T Hu H Yang T Topping A Yousefiani andE J Lavernia ldquoCoupling of dislocations and precipitatesImpact on the mechanical behavior of ultrafine grainedAlndashZnndashMg alloysrdquo Acta Materialia vol 103 pp 153ndash1642016

[79] P K Rout M M Ghosh and K S Ghosh ldquoMicrostructuralmechanical and electrochemical behaviour of a 7017 AlndashZnndashMg alloy of different tempersrdquo Materials Character-ization vol 104 pp 49ndash60 2015

[80] K Sotoudeh and P S Bate ldquoDiffusion creep and super-plasticity in aluminium alloysrdquo Acta Materialia vol 58no 6 pp 1909ndash1920 2010

[81] J Liu and D J Chakrabarti ldquoGrain structure and micro-texture evolution during superplastic forming of a high

strength AlndashZnndashMgndashCu alloyrdquo Acta Materialia vol 44no 12 pp 4647ndash4661 1996

[82] X Cao G Xu Y Duan Z Yin and L Lu ldquoAchieving highsuperplasticity of a new AlndashMgndashScndashZr alloy sheet preparedby a simple thermalndashmechanical processrdquo Materials Scienceand Engineering A vol 647 pp 333ndash343 2015

[83] X Xu J Zheng Z Li R Luo and B Chen ldquoPrecipitation inan Al-Zn-Mg-Cu alloy during isothermal aging Atomic-scale HAADF-STEM investigationrdquo Materials Science andEngineering A vol 691 pp 60ndash70 2017

[84] K Wen Y Fan G Wang L Jin X Li and Z Li ldquoAgingbehavior and fatigue crack propagation of high Zn-con-taining Al-Zn-Mg-Cu alloys with zinc variationrdquo MaterialsScience and Engineering A vol 27 pp 217ndash227 2017

[85] F Jiang H S Zurob G R Purdy and H Zhang ldquoChar-acterizing precipitate evolution of an Al-Zn-Mg-Cu-basedcommercial alloy during artificial aging and non-iso-thermal heat treatments by in situ electrical resistivitymonitoringrdquoMaterials Science and Engineering A vol 117pp 47ndash56 2016

[86] KWang F C Liu Z Y Ma and F C Zhang ldquoRealization ofexceptionally high elongation at high strain rate in a frictionstir processed AlndashZnndashMgndashCu alloy with the presence ofliquid phaserdquo Scripta Materialia vol 64 no 6 pp 572ndash5752011

[87] A V Mikhaylovskaya O A Yakovtseva V V Cheverikinand A D kotov ldquoSuperplastic behaviour of Al-Mg-Zn-Zr-Sc-based alloys at high strain ratesrdquo Materials Science andEngineering A vol 659 pp 225ndash233 2016

[88] R Kaibyshev E Avtokratova A Apollonov and R DaviesldquoHigh strain rate superplasticity in an AlndashMgndashScndashZr alloysubjected to simple thermomechanical processingrdquo ScriptaMaterialia vol 54 no 12 pp 2119ndash2124 2006

[89] I Charit and R S Mishra ldquoLow temperature superplasticityin a friction-stir-processed ultrafine grained AlndashZnndashMgndashScalloyrdquo Acta Materialia vol 53 no 15 pp 4211ndash4223 2005

[90] R Raj ldquoA mechanistic basis for high strain rate superplas-ticity of aluminum based metal matrix compositesrdquo Mate-rials Science and Engineering vol 215 no 1-2 pp 1ndash8 1996

[91] V N Perevezentsev and K Higashi ldquoeoretical In-vestigation of High Strain Rate Superplasticityrdquo MaterialsScience Forum vol 304ndash306 pp 217ndash224 1999

[92] M Mabuchi K Higashi K Inoue et al ldquoExperimentalinvestigation of superplastic behavior in a 20 vol aluminumcompositerdquo Scripta Metallurgica et Materialia vol 26no 12 pp 1839ndash1844 1992

[93] K Higashi T Okada T Mukai et al ldquoSuperplastic behaviorin a mechanically alloyed aluminum composite reinforcedwith SiC particulatesrdquo Scripta Metallurgica et Materialiavol 26 no 2 pp 185ndash190 1992

[94] M Mabuchi K Higashi and T G Langdon ldquoAninvestigation of the role of a liquid phase in AlndashCundashMgmetal matrix composites exhibiting high strain rate super-plasticityrdquo Acta Metallurgica et Materialia vol 42 no 5pp 1739ndash1745 1994

[95] C Tang M Li Z Li et al ldquoSuperplasticity of Al compositefabricated by spray deposition processingrdquo Journal of Ma-terials Engineering vol 3 pp 17ndash19 1996

[96] G H Zahid R I Todd and P B Prangnell ldquoSuperplasticityin an alulllinium alloy 2124SiCp compositerdquo MaterialsScience and Technology vol 14 no 9 pp 901ndash905 1998

[97] X XuWWang and L Cai ldquoSuperplasticity of A SiCP6A02Al compositerdquoMaterials for Mechanical Engineering vol 26no 9 pp 20-21 2002


[98] X Xu K Chen F Dai and L Cai ldquoInvestigation on su-perplasticity of SiC particulate reinforced aluminum matrixcompositerdquo Acta Metallurgica Sinica vol 38 no 5pp 544ndash548 2000

[99] F R Cao H Ding Y L Li G Zhou and J Z Cui ldquoSu-perplasticity dynamic grain growth and deformationmechanism in ultra-light two-phase magnesiumndashlithiumalloysrdquo Materials Science and Engineering A vol 527 no 92010

[100] I I Novikov V K Portnoy V S Levchenko andA O Nikiforov ldquoSubscolidus superplasticity of aluminiumalloysrdquo Materials Science Forum vol 243ndash245 pp 463ndash4681997

[101] J C Tan and M J Tan ldquoSuperplasticity and grain boundarysliding characteristics in two stage deformation of Mgndash3Alndash1Zn alloy sheetrdquo Materials Science and Engineering Avol 339 no 1-2 pp 81ndash89 2003

[102] O A Ruano and O D Sherby ldquoOn constitutive equationsfor various diffusion-controlled creep mechanismsrdquo Revuede Physique Appliquee vol 23 no 4 pp 625ndash637 1988

[103] T G Nieh J Wadsworth and O D Sherby Superplasticityin Metals and Ceramics Cambridge University PressCambridge UK 1997

[104] M E Kassner andM T Perez-Prado ldquoFive-power-law creepin single phase metals and alloysrdquo Progress in MaterialsScience vol 45 no 1 pp 1ndash102 2000

[105] Y L Duan G F Xu D Xiao L Q Zhou Y Deng andZ M Yin ldquoExcellent superplasticity and deformationmechanism of AlndashMgndashScndashZr alloy processed via simple freeforgingrdquo Materials Science and Engineering A vol 624pp 124ndash131 2015

[106] J Liu and D J Chakrabarti ldquoGrain structure and micro-texture evolution during superplastic forming of a highstrength AlndashZnndashMgndashCu alloyrdquo Acta Materialia vol 44no 12 pp 4641ndash4661 1996

[107] X Cao G Xu Y Duan Z Yin and Y Wang ldquoAchievinghigh superplasticity of a new AlndashMgndashScndashZr alloy sheetprepared by a simple thermalndashmechanical processrdquo Mate-rials Science and Engineering A vol 647 pp 333ndash343 2015

[108] P S Bate F J Humpherys N Ridley and B ZhangldquoMicrostructure and texture evolution in the tension ofsuperplastic Alndash6Cundash04Zrrdquo Acta Materialia vol 53 no 10pp 3059ndash3069 2005

[109] S Katsas R Dashwood R Grimes M Jackson G Toddand H Henein ldquoDynamic recrystallisation and super-plasticity in pure aluminium with zirconium additionrdquoMaterials Science and Engineering A vol 444 no 1-2pp 291ndash297 2007


[111] R H Bricknell and J W Ddington ldquoSuperplasticity in thecommercial Al-Zn-Mg alloy BA 708rdquo Metallurgical Trans-actions A vol 7 no 1 pp 153-154 1976

[112] J A del Valle M Teresa PerezndashPrado and O A RuanoldquoSymbiosis between grain boundary sliding and slip creep toobtain high-strain-rate superplasticity in aluminum alloysrdquoJournal of the European Ceramic Society vol 27 no 11pp 3385ndash3390 2007

[113] L B Johannes and R S Mishra ldquoMultiple passes of frictionstir processing for the creation of superplastic 7075 alumi-numrdquoMaterials Science and Engineering A vol 464 no 1-2pp 255ndash260 2007

[114] A Ball ldquoSuperplasticity in the aluminium-zinc eutec-toidmdashan early model revisitedrdquo Materials Science and En-gineering A vol 234ndash236 pp 365ndash369 1997

[115] A K Mukherjee ldquoe rate controlling mechanism in su-perplasticityrdquo Materials Science and Engineering vol 8no 2 pp 83ndash89 1971

[116] R G Gifkins ldquoGrain-boundary sliding and its accommo-dation during creep and superplasticityrdquo MetallurgicalTransactions A vol 7 no 8 pp 1225ndash1232 1976

[117] A Ball and M M Hutchison ldquoSuperplasticity in theAluminiumndashZinc Eutectoidrdquo Journal of Metal Science vol 3pp 1ndash7 1969

[118] K Mukherjee ldquoe rate controlling mechanism in super-plasticityrdquo Materials Science and Engineering vol 8 no 2pp 83ndash89 1971

[119] M F Ashby and R A Verrall ldquoDiffusion-accommodatedflow and superplasticityrdquo Acta Metallurgica vol 21 no 2pp 149ndash163 1973

[120] W A Backofen I R Turner and D H Avery ldquoSuper-plasticity in an Al-Zn alloyrdquo Transactions of ASM vol 57pp 980ndash990 1964

[121] K I Sugimoto U Noboru M Kobayashi et al ldquoEffects ofvolume fraction and stability of retained austenite on duc-tility of TRIP-aided dual-phase steelsrdquo ISIJ Internationalvol 32 no 12 pp 1311ndash1318 1992

[122] A Orozco-Caballero and A Orozco-Caballero ldquoGrain sizeversus microstructural stability in the high strain ratesuperplastic response of a severely friction stir processedAl-Zn-Mg-Cu alloyrdquo Materials Science and Engineering Avol 680 pp 329ndash337 2017

[123] N Fakhar F Fereshteh-Saniee and R Mahmudi ldquoHighstrain-rate superplasticity of fine- and ultrafine-grainedAA5083 aluminum alloy at intermediate temperaturesrdquoMaterials and Design vol 85 pp 342ndash348 2015

[124] N Fakhar F Fereshteh-Saniee and R Mahmudi ldquoGrainrefinement and high strain rate superplasticity in alumunium2024 alloy processed by high-pressure torsionrdquo MaterialsScience and Engineering A vol 622 pp 139ndash145 2015

[125] J Lei W Xiaolu and L Hui ldquoHigh strain rate superplasticityof in situ Al 3 Zr6063Al compositesrdquo Rare Metal Materialsand Engineering vol 45 no 11 pp 2798ndash2803 2016

[126] B Kim J C Kim S Lee and K-S Lee ldquoHigh-strain-ratesuperplasticity of fine-grained Mgndash6Znndash05Zr alloy sub-jected to low-temperature indirect extrusionrdquo ScriptaMaterialia vol 141 pp 138ndash142 2017

[127] A Orozco-Caballero C M Cepeda-Jimenez andP Hidalgo-Manrique ldquoLowering the temperature for highstrain rate superplasticity in an AlndashMgndashZnndashCu alloy viacooled friction stir processingrdquo Materials Chemistry andPhysics vol 142 no 1 pp 182ndash185 2013

[128] Z Y Ma R S Mishra M W Mahoney and R GrimesldquoHigh strain rate superplasticity in friction stir processedAlndashMgndashZr alloyrdquo Materials Science and Engineering Avol 351 no 1-2 pp 148ndash153 2003

[129] Z Y Ma and R S Mishra ldquoDevelopment of ultrafine-grained microstructure and low temperature (048 Tm)superplasticity in friction stir processed AlndashMgndashZrrdquo ScriptaMaterialia vol 53 pp 75ndash80 2005

[130] T G Nieh L M Hsiung J Wadsworth and R KaibyshevldquoHigh strain rate superplasticity in a continuously recrys-tallized Alndash6Mgndash03Sc alloyrdquo Acta Materialia vol 46no 8 pp 2789ndash2880 1998


[131] K L Kending and D B Miracle ldquoStrengthening mecha-nisms of an Al-Mg-Sc-Zr alloyrdquo Acta Materialia vol 50no 16 pp 4165ndash4175 2002

[132] Y NWang and J C Huang ldquoComparison of grain boundarysliding in fine grained Mg and Al alloys during superplasticdeformationrdquo Scripta Materialia vol 48 no 8 pp 1117ndash1122 2003

[133] K T Park S H Myung D H Shin and C S Lee ldquoSize anddistribution of particles and voids pre-existing in equalchannel angular pressed 5083 Al alloy their effect on cav-itation during low-temperature superplastic deformationrdquoMaterials Science and Engineering vol 371 no 1-2pp 178ndash186 2004


CorrosionInternational Journal of

Hindawiwwwhindawicom Volume 2018

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Materials Science and EngineeringHindawiwwwhindawicom Volume 2018


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Analytical ChemistryInternational Journal of


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Polymer ScienceInternational Journal of



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High Energy PhysicsAdvances in

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

TribologyAdvances in



ChemistryAdvances in


Advances inPhysical Chemistry


BioMed Research InternationalMaterials

Journal of


Na

nom

ate

ria

ls


Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom

complex shapes in sheet or tube e Al alloys used arecapable of achieving equivalent thickness strains in excess of300 at low strain rates Companies like Superform andAlcoa have successfully applied SFT to produce Al alloyautomobile parts (decklid fenders door inners and brakedisk) with 50 weight saving [15] In 1991 8090 Al alloyswere used to produce military aircraft doors by SFT with23 weight reduction and 68 cost reduction

To enhance the superplastic formability of Al alloys it isnecessary to make the alloys to go through several advancedforming technologies such as flake powder metallurgy [16]and cryo-deformation [17ndash20] as well as severe plasticdeformation (SPD) [21] including friction stir processing(FSP) [22ndash28] equal-channel angular pressing (ECAP)[29ndash35] high-pressure torsion (HTP) [36] accumulative rollbonding (ARB) [37] multiaxial alternative forging (MAF)[38] and repetitive corrugation and straightening (RCS)[39 40] After SPD process ultrafine grain high super-plasticity and low flow stress are available for Al alloys Yetdue to high cost additionally required technologies mayhold back the direct and full commercial application of SPDtechnology Meanwhile more and more energy and re-sources are pouring into developing new and convenienthotcold mechanical processing for superplasticity ofvarious Al alloys erefore thermal-mechanical pro-cessing (TMP) [41ndash43] which is mainly based on theprinciples of static recrystallisation [44ndash47] and dynamicrecrystallisation [48 49] is also an important way to de-velop superplasticity of Al alloys

2 FundamentalsofSuperplasticDeformationofAl Alloys

21 Stacking Fault Energy It is well known that Al and Alalloys are with high stacking fault energy (SFE) which isa significant intrinsic material parameter that would changemechanisms and grain refinement during superplastic de-formation In Al and Al alloys recovery is not totally sup-pressed during superplastic deformation Additionallylowering the SFE would promote deformation twinning overdislocation slip and increase dislocation slip-twinning tran-sition temperature [50 51]

22 Strain-HardeningAbility It is clear that strain hardeningis a typical phenomenon in plastic deformation In the pri-mary stage of superplastic deformation flow stress rapidlyrises with flow strain due to appearance of massive defects(vacanciesdislocationstwinning) As the process goes onstrain softening due to recoveryrecrystallisationcross slipstarts to offset or partially offset the increase of flow stressuntil there is a dynamic balance between the hardening andsoftening processes namely steady stage of superplasticdeformation e strain-hardening ability is strongly de-pendant on temperature and strain rate of superplastic de-formation as shown in Figure 1e true stress increases withincrease in strain rate and decrease in temperature which isexplained in Section 42

23 SuperplasticDeformationBehavior After rolling or SPDAl alloys consist of banded microstructure with subgrainboundaries (SGBs) and low-angle boundaries (LABs) Fol-lowing homogenization annealing Al alloys are recrystallisedand themicrostructure combined with equiaxed recrystallisedgrains with weakened banded grains is formed beforesuperplastic tensile tests e early stage of superplastic de-formation of Al alloys is usually accompanied with staticdynamic grain growth and anisotropic grain elongation Itshould be noticed that grains are more elongated in the tensiledirection than in the transverse direction [53 54] Yet thestaticdynamic grain growth is closely related to the distri-bution of intermetallic precipitates which is fully discussed inSection 42 With the increase in strain the previous mi-crostructure is replaced by a more equiaxed and uniformgrain structure and the banded grains are vanished

24 Crystallographic Texture Crystallographic texture isa preferred orientation structure of grains in ploycrystallinematerials

Being subjected to the formation process (casting rollingrecrystallisation and heat treatment) Al and Al alloys typicalFCC ploycrystalline materials would produce correspondingtexture e main crystallographic texture components inFCC metals are listed in Table 1

Prior to superplastic deformation the microtexture ofrolledSPD Al alloys is of a strong brass texture [17 55]which is a dominant plane strain hot deformation texture forAl alloys After homogenization annealing for proper periodAl alloys exhibit cube near cube rotated cube or decreasedbrass component As the strain of superplastic deformationincreases a randomization of the microtexture happensalong with the increase inmisoriented boundaries thereforethe alloys exhibit a very weak texture component as cubenear cube rotated cube or decreased brass componentFigure 2 shows ODFs representative sections of Al-Zn-Mg-025Sc-010Zr during superplastic deformation In sum-mary the overall texture intensity of Al alloys is substantiallyreduced following superplastic deformation and no neworientation is developed

25 Strain Rate Sensitivity (m) and Deformation ActivationEnergy (Q) Usually superplastic deformation can be de-scribed by an equation for power-law creep in the followingform

_ε AD0Gb

RT

b

d1113888 1113889

p σG

1113874 11138751m

exp minusQ

RT1113874 1113875 (4)

where _ε the is strain rate Q is the activation energy of anappropriate diffusion process A and p are the empiricalmaterial constants G is the shear modulus b is the Burgersvector R is the gas constant T is the absolute temperatureD0 is the frequency factor andm is the strain rate sensitivityexponent (1m is the stress exponent n n 1m)

Strain rate sensitivity (m) is a critical parameter forsuperplastic deformation as its value characterizes theability of an alloy to resist necking spread during



m z ln σz log _ε

11138681113868111386811138681113868111386811138681113868T (5)




Q R

m

z ln σz(1T)

1113868111386811138681113868111386811138681113868_ε (6)



True

stre

ss (M

Pa) 25

20

15

10

5

30

00 04 08 12 16 20 24True strain



(a)Tr

ue st

ress

(MPa

)

True strain00 04 08 12 16 20 24

25

20

15

10

5

30



(b)

True

stre

ss (M

Pa)

True strain00 04 08 12 16 20 24

25

20

15

10

5

30



(c)

True

stre

ss (M

Pa)

True strain



00 04 08 12 16 20 24

25

20

15

10

5

30

(d)

True

stre

ss (M

Pa)

True strain00 04 08 12 16 20 24

25

20

15

10

5

30



(e)





0deg

65deg

45degMax = 32959330001639981494050201210000497Min = ndash2941

(a)

65deg


(b)

65deg


(c)

65deg

0deg 45degMax = 2151330001639981494050201210000497Min = 0230

(d)





90ndash126107 [43]


838ndash850845 [42]


838ndash85685 [56]


93269ndash177517143762 [57]

















4 Discussion
























10 μm


TT

T

T

σ

σ











Stressconcentration


sliding plane



dislocation


Slidingdirection



Gifkinsmodel [116]

Grain A

Grain C

Grain B

Newdislocation

Slidingdirection




dimensional space

300

400

500

600

700

800

900

1000

Supe

rpla

stic e

long

atio

n (

)


Alloy typeAl-Li-Cu


0006670001015


Al-Zn-Mg-Zr-Sc



1200

1000

800

600

400

200

0

Elon

gatio

n (

)

10ndash3 10ndash2



500degC

525degC

850

800

750

700

650

Supe

rpla

stic e

long

atio

n (

)


600

550

50000012 00018 00024

480degC470degC

490degC

00 03 06 09 12 15

Elon

gatio

n (

)

10ndash3 10ndash2


Supe

rpla

stic e

long

atio

n (

)


5001000

800

600

400

200

450

400

350

300

250

200

150

450degC480degC

525degC540degC

510degC


(a) (b)

Figure 7 Continued







(c) (d)


(a) (b)


440

500

1000

1500

2000

2500

3000

3500


Max

imum

elon

gatio

n (

)

500 520 540










030

025

020

015

010

005

00010 20 30 40 50 60

Freq

uenc

y


fHABs = 273

(a)

018

014

016

012

010

006

004

008

002

00010 20 30 40 50 60

Freq

uenc

y

fHABs = 435


(b)

000

001

002

003

004

005

006

Freq

uenc

y


fHABs = 759

10 20 30 40 50 60

(c)

10 20 30 40 50 60000

001

002

003

004

005

Freq

uenc

y


fHABs = 988

(d)








6 Conclusions




(a)

(c)

(b)

(d)



References

















































































































































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls





m z ln σz log _ε

11138681113868111386811138681113868111386811138681113868T (5)




Q R

m

z ln σz(1T)

1113868111386811138681113868111386811138681113868_ε (6)



True

stre

ss (M

Pa) 25

20

15

10

5

30

00 04 08 12 16 20 24True strain



(a)Tr

ue st

ress

(MPa

)

True strain00 04 08 12 16 20 24

25

20

15

10

5

30



(b)

True

stre

ss (M

Pa)

True strain00 04 08 12 16 20 24

25

20

15

10

5

30



(c)

True

stre

ss (M

Pa)

True strain



00 04 08 12 16 20 24

25

20

15

10

5

30

(d)

True

stre

ss (M

Pa)

True strain00 04 08 12 16 20 24

25

20

15

10

5

30



(e)





0deg

65deg

45degMax = 32959330001639981494050201210000497Min = ndash2941

(a)

65deg


(b)

65deg


(c)

65deg

0deg 45degMax = 2151330001639981494050201210000497Min = 0230

(d)





90ndash126107 [43]


838ndash850845 [42]


838ndash85685 [56]


93269ndash177517143762 [57]

















4 Discussion
























10 μm


TT

T

T

σ

σ











Stressconcentration


sliding plane



dislocation


Slidingdirection



Gifkinsmodel [116]

Grain A

Grain C

Grain B

Newdislocation

Slidingdirection




dimensional space

300

400

500

600

700

800

900

1000

Supe

rpla

stic e

long

atio

n (

)


Alloy typeAl-Li-Cu


0006670001015


Al-Zn-Mg-Zr-Sc



1200

1000

800

600

400

200

0

Elon

gatio

n (

)

10ndash3 10ndash2



500degC

525degC

850

800

750

700

650

Supe

rpla

stic e

long

atio

n (

)


600

550

50000012 00018 00024

480degC470degC

490degC

00 03 06 09 12 15

Elon

gatio

n (

)

10ndash3 10ndash2


Supe

rpla

stic e

long

atio

n (

)


5001000

800

600

400

200

450

400

350

300

250

200

150

450degC480degC

525degC540degC

510degC


(a) (b)

Figure 7 Continued







(c) (d)


(a) (b)


440

500

1000

1500

2000

2500

3000

3500


Max

imum

elon

gatio

n (

)

500 520 540










030

025

020

015

010

005

00010 20 30 40 50 60

Freq

uenc

y


fHABs = 273

(a)

018

014

016

012

010

006

004

008

002

00010 20 30 40 50 60

Freq

uenc

y

fHABs = 435


(b)

000

001

002

003

004

005

006

Freq

uenc

y


fHABs = 759

10 20 30 40 50 60

(c)

10 20 30 40 50 60000

001

002

003

004

005

Freq

uenc

y


fHABs = 988

(d)








6 Conclusions




(a)

(c)

(b)

(d)



References

















































































































































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls




0deg

65deg

45degMax = 32959330001639981494050201210000497Min = ndash2941

(a)

65deg


(b)

65deg


(c)

65deg

0deg 45degMax = 2151330001639981494050201210000497Min = 0230

(d)





90ndash126107 [43]


838ndash850845 [42]


838ndash85685 [56]


93269ndash177517143762 [57]

















4 Discussion
























10 μm


TT

T

T

σ

σ











Stressconcentration


sliding plane



dislocation


Slidingdirection



Gifkinsmodel [116]

Grain A

Grain C

Grain B

Newdislocation

Slidingdirection




dimensional space

300

400

500

600

700

800

900

1000

Supe

rpla

stic e

long

atio

n (

)


Alloy typeAl-Li-Cu


0006670001015


Al-Zn-Mg-Zr-Sc



1200

1000

800

600

400

200

0

Elon

gatio

n (

)

10ndash3 10ndash2



500degC

525degC

850

800

750

700

650

Supe

rpla

stic e

long

atio

n (

)


600

550

50000012 00018 00024

480degC470degC

490degC

00 03 06 09 12 15

Elon

gatio

n (

)

10ndash3 10ndash2


Supe

rpla

stic e

long

atio

n (

)


5001000

800

600

400

200

450

400

350

300

250

200

150

450degC480degC

525degC540degC

510degC


(a) (b)

Figure 7 Continued







(c) (d)


(a) (b)


440

500

1000

1500

2000

2500

3000

3500


Max

imum

elon

gatio

n (

)

500 520 540










030

025

020

015

010

005

00010 20 30 40 50 60

Freq

uenc

y


fHABs = 273

(a)

018

014

016

012

010

006

004

008

002

00010 20 30 40 50 60

Freq

uenc

y

fHABs = 435


(b)

000

001

002

003

004

005

006

Freq

uenc

y


fHABs = 759

10 20 30 40 50 60

(c)

10 20 30 40 50 60000

001

002

003

004

005

Freq

uenc

y


fHABs = 988

(d)








6 Conclusions




(a)

(c)

(b)

(d)



References

















































































































































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls

















4 Discussion
























10 μm


TT

T

T

σ

σ











Stressconcentration


sliding plane



dislocation


Slidingdirection



Gifkinsmodel [116]

Grain A

Grain C

Grain B

Newdislocation

Slidingdirection




dimensional space

300

400

500

600

700

800

900

1000

Supe

rpla

stic e

long

atio

n (

)


Alloy typeAl-Li-Cu


0006670001015


Al-Zn-Mg-Zr-Sc



1200

1000

800

600

400

200

0

Elon

gatio

n (

)

10ndash3 10ndash2



500degC

525degC

850

800

750

700

650

Supe

rpla

stic e

long

atio

n (

)


600

550

50000012 00018 00024

480degC470degC

490degC

00 03 06 09 12 15

Elon

gatio

n (

)

10ndash3 10ndash2


Supe

rpla

stic e

long

atio

n (

)


5001000

800

600

400

200

450

400

350

300

250

200

150

450degC480degC

525degC540degC

510degC


(a) (b)

Figure 7 Continued







(c) (d)


(a) (b)


440

500

1000

1500

2000

2500

3000

3500


Max

imum

elon

gatio

n (

)

500 520 540










030

025

020

015

010

005

00010 20 30 40 50 60

Freq

uenc

y


fHABs = 273

(a)

018

014

016

012

010

006

004

008

002

00010 20 30 40 50 60

Freq

uenc

y

fHABs = 435


(b)

000

001

002

003

004

005

006

Freq

uenc

y


fHABs = 759

10 20 30 40 50 60

(c)

10 20 30 40 50 60000

001

002

003

004

005

Freq

uenc

y


fHABs = 988

(d)








6 Conclusions




(a)

(c)

(b)

(d)



References

















































































































































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls























10 μm


TT

T

T

σ

σ











Stressconcentration


sliding plane



dislocation


Slidingdirection



Gifkinsmodel [116]

Grain A

Grain C

Grain B

Newdislocation

Slidingdirection




dimensional space

300

400

500

600

700

800

900

1000

Supe

rpla

stic e

long

atio

n (

)


Alloy typeAl-Li-Cu


0006670001015


Al-Zn-Mg-Zr-Sc



1200

1000

800

600

400

200

0

Elon

gatio

n (

)

10ndash3 10ndash2



500degC

525degC

850

800

750

700

650

Supe

rpla

stic e

long

atio

n (

)


600

550

50000012 00018 00024

480degC470degC

490degC

00 03 06 09 12 15

Elon

gatio

n (

)

10ndash3 10ndash2


Supe

rpla

stic e

long

atio

n (

)


5001000

800

600

400

200

450

400

350

300

250

200

150

450degC480degC

525degC540degC

510degC


(a) (b)

Figure 7 Continued







(c) (d)


(a) (b)


440

500

1000

1500

2000

2500

3000

3500


Max

imum

elon

gatio

n (

)

500 520 540










030

025

020

015

010

005

00010 20 30 40 50 60

Freq

uenc

y


fHABs = 273

(a)

018

014

016

012

010

006

004

008

002

00010 20 30 40 50 60

Freq

uenc

y

fHABs = 435


(b)

000

001

002

003

004

005

006

Freq

uenc

y


fHABs = 759

10 20 30 40 50 60

(c)

10 20 30 40 50 60000

001

002

003

004

005

Freq

uenc

y


fHABs = 988

(d)








6 Conclusions




(a)

(c)

(b)

(d)



References

















































































































































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls












10 μm


TT

T

T

σ

σ











Stressconcentration


sliding plane



dislocation


Slidingdirection



Gifkinsmodel [116]

Grain A

Grain C

Grain B

Newdislocation

Slidingdirection




dimensional space

300

400

500

600

700

800

900

1000

Supe

rpla

stic e

long

atio

n (

)


Alloy typeAl-Li-Cu


0006670001015


Al-Zn-Mg-Zr-Sc



1200

1000

800

600

400

200

0

Elon

gatio

n (

)

10ndash3 10ndash2



500degC

525degC

850

800

750

700

650

Supe

rpla

stic e

long

atio

n (

)


600

550

50000012 00018 00024

480degC470degC

490degC

00 03 06 09 12 15

Elon

gatio

n (

)

10ndash3 10ndash2


Supe

rpla

stic e

long

atio

n (

)


5001000

800

600

400

200

450

400

350

300

250

200

150

450degC480degC

525degC540degC

510degC


(a) (b)

Figure 7 Continued







(c) (d)


(a) (b)


440

500

1000

1500

2000

2500

3000

3500


Max

imum

elon

gatio

n (

)

500 520 540










030

025

020

015

010

005

00010 20 30 40 50 60

Freq

uenc

y


fHABs = 273

(a)

018

014

016

012

010

006

004

008

002

00010 20 30 40 50 60

Freq

uenc

y

fHABs = 435


(b)

000

001

002

003

004

005

006

Freq

uenc

y


fHABs = 759

10 20 30 40 50 60

(c)

10 20 30 40 50 60000

001

002

003

004

005

Freq

uenc

y


fHABs = 988

(d)








6 Conclusions




(a)

(c)

(b)

(d)



References

















































































































































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls












Stressconcentration


sliding plane



dislocation


Slidingdirection



Gifkinsmodel [116]

Grain A

Grain C

Grain B

Newdislocation

Slidingdirection




dimensional space

300

400

500

600

700

800

900

1000

Supe

rpla

stic e

long

atio

n (

)


Alloy typeAl-Li-Cu


0006670001015


Al-Zn-Mg-Zr-Sc



1200

1000

800

600

400

200

0

Elon

gatio

n (

)

10ndash3 10ndash2



500degC

525degC

850

800

750

700

650

Supe

rpla

stic e

long

atio

n (

)


600

550

50000012 00018 00024

480degC470degC

490degC

00 03 06 09 12 15

Elon

gatio

n (

)

10ndash3 10ndash2


Supe

rpla

stic e

long

atio

n (

)


5001000

800

600

400

200

450

400

350

300

250

200

150

450degC480degC

525degC540degC

510degC


(a) (b)

Figure 7 Continued







(c) (d)


(a) (b)


440

500

1000

1500

2000

2500

3000

3500


Max

imum

elon

gatio

n (

)

500 520 540










030

025

020

015

010

005

00010 20 30 40 50 60

Freq

uenc

y


fHABs = 273

(a)

018

014

016

012

010

006

004

008

002

00010 20 30 40 50 60

Freq

uenc

y

fHABs = 435


(b)

000

001

002

003

004

005

006

Freq

uenc

y


fHABs = 759

10 20 30 40 50 60

(c)

10 20 30 40 50 60000

001

002

003

004

005

Freq

uenc

y


fHABs = 988

(d)








6 Conclusions




(a)

(c)

(b)

(d)



References

















































































































































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls




1200

1000

800

600

400

200

0

Elon

gatio

n (

)

10ndash3 10ndash2



500degC

525degC

850

800

750

700

650

Supe

rpla

stic e

long

atio

n (

)


600

550

50000012 00018 00024

480degC470degC

490degC

00 03 06 09 12 15

Elon

gatio

n (

)

10ndash3 10ndash2


Supe

rpla

stic e

long

atio

n (

)


5001000

800

600

400

200

450

400

350

300

250

200

150

450degC480degC

525degC540degC

510degC


(a) (b)

Figure 7 Continued







(c) (d)


(a) (b)


440

500

1000

1500

2000

2500

3000

3500


Max

imum

elon

gatio

n (

)

500 520 540










030

025

020

015

010

005

00010 20 30 40 50 60

Freq

uenc

y


fHABs = 273

(a)

018

014

016

012

010

006

004

008

002

00010 20 30 40 50 60

Freq

uenc

y

fHABs = 435


(b)

000

001

002

003

004

005

006

Freq

uenc

y


fHABs = 759

10 20 30 40 50 60

(c)

10 20 30 40 50 60000

001

002

003

004

005

Freq

uenc

y


fHABs = 988

(d)








6 Conclusions




(a)

(c)

(b)

(d)



References

















































































































































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls









(c) (d)


(a) (b)


440

500

1000

1500

2000

2500

3000

3500


Max

imum

elon

gatio

n (

)

500 520 540










030

025

020

015

010

005

00010 20 30 40 50 60

Freq

uenc

y


fHABs = 273

(a)

018

014

016

012

010

006

004

008

002

00010 20 30 40 50 60

Freq

uenc

y

fHABs = 435


(b)

000

001

002

003

004

005

006

Freq

uenc

y


fHABs = 759

10 20 30 40 50 60

(c)

10 20 30 40 50 60000

001

002

003

004

005

Freq

uenc

y


fHABs = 988

(d)








6 Conclusions




(a)

(c)

(b)

(d)



References

















































































































































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls










030

025

020

015

010

005

00010 20 30 40 50 60

Freq

uenc

y


fHABs = 273

(a)

018

014

016

012

010

006

004

008

002

00010 20 30 40 50 60

Freq

uenc

y

fHABs = 435


(b)

000

001

002

003

004

005

006

Freq

uenc

y


fHABs = 759

10 20 30 40 50 60

(c)

10 20 30 40 50 60000

001

002

003

004

005

Freq

uenc

y


fHABs = 988

(d)








6 Conclusions




(a)

(c)

(b)

(d)



References

















































































































































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls









6 Conclusions




(a)

(c)

(b)

(d)



References

















































































































































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls




References

















































































































































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls

















































































































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls















































































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls












































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls










Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls






Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls




Documents

ReviewArticle AReviewonSuperplasticFormationBehaviorofAlAlloysdownloads.hindawi.com/journals/amse/2018/7606140.pdf · deformation.elargerthevalueofstrainratesensitivity is, the greater