Journal of Materials Science and Engineering A 10 (3-4) (2020) 60-64 doi: 10.17265/2161-6213/2020.3-4.003

Influence of the Deep Cryogenic Treatment at the Stabilization of Martensitic Transformation Temperatures at the Smart Material Alloy Cu-14Al-4Ni

Emmanuel Pacheco Rocha Lima, Marcelo Nava and Pedro Cunha de Lima Faculdade do Gama, Universidade de Brasília, Gama 72444-240, Brasil Abstract: DCT (deep cryogenic treatment) is commonly used in industry to improve the wear resistance characteristics of steels, especially. However, there are just a few researches about the effects on non-ferrous metals. The purpose of this work was to investigate how DCT affects the properties of Cu-14Al-4Ni alloy treated at different soak time and submitted to thermomechanical cycling. A comparative experimental analysis was performed of the thermal properties of alloys obtained on a vacuum furnace, treated by DCT and thermomechanically cyclized. The results indicates that thermomechanical cycling promoted the appearance and growth of the martensitic phase γ'1, less ductile than the martensitic phase β'1, which together with the induced hardening produced an increase in transformation temperatures and microhardness. The higher the number of cycles, the greater these effects. The DCT promoted an increase in the intensity of the diffraction peaks corresponding to the phase β'1 and the maintenance of them during the thermomechanical cycling of the material, which indicates that the DCT stabilizes the martensitic phase β'1 and, consequently, caused a reduction and stabilization of the martensitic transformation temperatures and the microhardness, when compared to the untreated material. The longer the soaking time of DCT, the greater these effects.

Key words: DCT, SMA (shape memory alloy), Cu-Al-Ni alloy.

Nomenclature

DCT deep cryogenic treatment SMA shape memory alloy

EDS energy dispersive spectroscopy

XRD X-ray diffraction

T Mpeak peak temperature of martensitic transformation

T Apeak peak temperature of austenitic transformation

Greek Letters

β'1 martensitic phase

γ'1 martensitic phase

β1 high temperature phase

2θ diffraction angle

1. Introduction

The study of shape memory alloys (SMAs) has been explored in recent decades, due to their properties, such as mechanical work due to the shape change of the material when exposed to different temperatures [1]. SMAs are a group of metallic

Corresponding author: Emmanuel Pacheco Rocha Lima,

Ph.D., professor, research fields: phase transformation, shape memory alloys, metallurgy.

materials with the property to recover the original shape (shape memory effect) by imposing higher temperatures, due to inducing phase transformations in the material and thermoelastic properties of pseudoelasticity [2, 3].

Cu-Al-Ni system alloys have good thermomechanical properties, good shape recovery and higher hysteresis. Another factor that justifies the use of this type of system is its low cost of material acquisition and certain facilities observed at the alloy’s manufacturing, reducing the cost of production in relation to Ni-Ti based systems [4, 5].

One of the factors that reduce the application of Cu-Al-Ni alloys is the reduction of the stabilization capacity of the martensitic/austenitic phases.

Different processes for the elaboration of SMA have been studied along the techniques of thermomechanical treatment and addition of refining elements in order to reduce the level of complexity of the austenite/martensite transformation, like the DCT (deep cryogenic treatment) [6-8].

DCT is treatment that consists of using temperatures closer to liquid nitrogen temperature (-196°C) and subsequent stabilization at room temperature, in order to obtain certain properties, such as high wear resistance, toughness, hardness and compressive residual stress, among others, and the use of this process is increasing [9]. However, further

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at the Stabiliz Material Allo

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Conclusion

This work irmomechanicmitted to Drmomechanicin conclusion1) Based onnufacturing pα-phase, hig

d producedcrostructure o2) DCT indufraction peakresponding tointenance of ling of the maordered ortho3) DCT prod

crohardness rmomechanicated to the staase of the Alrtensitic phaspe memory eT, the greater4) Related toe of the DCT

mples, the gremperatures ofnsformation. Ternal dampingrtensite platecrostructural ogenic treatmse defects interesis of the5) DCT didin sizes.

knowledgm

The authors port of FAPDDistrito Fede

zation of Martoy Cu-14Al-4N

the rate of mnumber of cy

he longer thecrohardness o

number of DCT must be ructile martenthe shape mem

ns

investigated cal changes aDCT, at dically cycled ns are: n the diffracprocess supprh copper hard

d an ortof AlCu3 (β'1) uced the incres (increase oo the phase (βf these durinaterial, indicatorhombic maduced a sens

of the mcal cycling. abilization of lCu3 type (β'se (γ´1) and reffect. The lor these effect

o the hysteresT, for the theeater the difff the direct This behaviog of the mate

es) and this, defects, in

ment may havn order to ca material.

d not produc

ments

gratefully acDF (Fundaçãral).

tensitic Ni

microhardnesycles is smalle DCT soakiof the mater

cycles. Thirelated to the

nsitic phase mory effect [

the microstrat the Cu-14Afferent soakin different

ction analysressed the predness intermethorhombic type, typical

ease in the intf the volumeβ'1) and, consng the thermting that the Dartensitic phassitive stabilizmaterial suThis behav

f the orthorho'1), more ducresponsible foonger the soas.

sis, the higherermomechanference betwe

and reverseor is directly rerial (frictionto several ph

such a wve acted in sause this inc

ce significant

cknowledge tão de Ampar

63

ss increasingler). ing time, therial increasesis behaviorale stabilizationβ'1 which is10].

ructural andAl-4Ni alloy

k time, andcycles. The

is, the usedecipitation ofetallic phase,

martensiticl of SMA. tensity of the

etric fraction)sequently, the

momechanicalDCT stabilizedse (β'1). zation of theubmitted tovior may beombic orderlyctile than theor the alloy’saking time of

r the soakingically cycledeen the peake martensiticrelated to the

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Influence of the Deep Cryogenic Treatment at the Stabilization of Martensitic Transformation Temperatures at the Smart Material Alloy Cu-14Al-4Ni

64

References

[1] Balo, S. N., and Ceylan M. 2002. “Effect of Be Content

on Some Characteristics of Cu-Al-Be Shape Memory

Alloys.” Ph.D. thesis, Firat University.

[2] Otsuka, K., and Wayman M. 1998. Shape Memory

Materials. Cambridge: Cambridge University Press.

[3] Isalgue, A., Fernandez, J., Torra, V., and Lovey, F. C.

2006. “Conditioning Treatments of Cu-Al-Be Shape

Memory Alloys for Dampers.” Ph.D. thesis, Dep. Física

Aplicada UPC, Campus Nord.

[4] Liu, J. 2016. “Microstructure and Properties of Cu-3Ti-1Ni

Alloy with Aging Process.” Ph.D. thesis, Shaanxi Key

Laboratory of Electrical Materials and Infiltration Technology.

[5] Juan, J. N. 2009. “Nanoscale Shape Memory Alloys for

Ultrahigh Mechanical Damping.” Nat. Nanotech 4: 415-9.

[6] Vinothkumar, T. S., Rajadurai, A., and Kandaswamy, D.

2015. “Effect of Dry Cryogenic Treatment on Vickers

Hardness and Wear Resistance of New Martensitic Shape

Memory Nickel-Titanium Alloy.” European Journal of

Dentistry 4: 513-7.

[7] Baldissera, P., and Delprete, C. 2008. “Deep Cryogenic

Treatment: A Bibliographic Review.” The Open

Mechanical Engineering Journal 2: 1-11.

[8] Vinothkumar, T. S., Prabhakaran G., Rajadurai, A., and

Kandaswamy, D. 2016. “Mechanical Behavior of Deep

Cryogenically Treated Martensitic Shape Memory

Nickel-Titanium Rotary Endodontic Instruments.”

European Journal of Dentistry 2: 183-7.

[9] Bensely, A., et al. 2006. “Enhancing the Wear Resistance

of Case Carburized Steel by Cryogenic Treatment.

Cryogenics.” Materials Characterization 5: 485-91.

[10] Lima, P. C. 2018. “Estudo do efeito da adição de titânio no tamanho de grão, nas temperaturas de transformação de fase e no módulo elástico da liga Cu-14Al-4Ni com efeito memória de forma obtida por fusão a arco e solidificação rápida a vácuo.” Ph.D. thesis, Universidade de Brasília. (in Portuguese)