Microstructure and Wear Behavior of Laser CladMulti-layered Fe-based Amorphous Coatings on SteelSubstrates

Tanaji Paul1 & S. Habib Alavi1 & Sourabh Biswas1 &

Sandip P. Harimkar1

Accepted: 26 August 2015 /Published online: 3 September 2015# Springer New York 2015

Abstract Single and multi-layered (with two and three layers) coatings ofFe48Cr15Mo14Y2C15B6 amorphous alloy were applied to AISI 1018 steel substratesvia laser cladding. XRD analysis indicated partial retention of the amorphous phasealong with the formation of oxide and carbide phases. Cross-sectional SEM micro-graphs revealed relatively sound coatings laser clad with single layer of amorphousalloy; however, cracks and voids were observed in the two and three layered amor-phous coatings. The specimens with single and two layered amorphous coatingsexhibited surface hardness of about 650 VHN while the hardness of the specimenswith three layered amorphous coatings (~1100 VHN) nearly equaled the hardness ofpreviously reported sintered amorphous alloys of similar compositions. The ball-on-disc wear analysis demonstrated a reverse trend wherein the single and two layeredamorphous coatings exhibited lower weight loss during the wear test cycle due tosuperior surface soundness while the three layered amorphous coatings showed aggra-vated wear due to internal voids and cracks.

Keywords Laser cladding . Amorphous alloy .Metallic glass . Compositional dilution .

Wear

Lasers Manuf. Mater. Process. (2015) 2:231–241DOI 10.1007/s40516-015-0017-0

* Sandip P. Harimkarsandip.harimkar@okstate.edu

1 School of Mechanical and Aerospace Engineering, Oklahoma State University, Stillwater,OK 74078, USA

Introduction

Steel has historically been one of the most popular structural materials due to its lowcost, ease of fabrication, and flexibility in design. However, the surface degradation ofsteel components due to exposure to harsh environmental conditions incurs high cost ofrepair and component replacement. This motivated simultaneous quest for novelcoatings alongside their application procedures that would improve their tribologicaland electrochemical properties. Initial endeavors in this quest included deposition ofmetallic coatings (nickel, chromium, zinc and cadmium) and ceramic coatings (alumi-num oxide and silicon carbide) [1–4] that eventually gave way to more novel tech-niques such as thermal spraying [5–7] and chemical vapor deposition [8].

Amorphous alloys exhibit higher hardness and strength as compared to their poly-crystalline counterparts [9] primarily due to their defect free disordered atomic struc-ture, and their development has ushered a new direction in the exploration of protectivecoatings for steels. The amorphous alloys show excellent resistance to wear andcorrosion, making them potential candidates for metal protective coatings [10, 11].Several iron-based amorphous systems such as binary (Fe-Si, Fe-Nb [12], Fe-B [11]),ternary (Fe-Si-B [10]), and complex multi-component (Fe-Ni-Cr-B-C, Fe-Ni-Cr-Mo-B-C [13] and Fe-Cr-Mo-W-Mn-C-Si-B [14]) systems have been investigated for theirapplicability as coating materials. The high temperature and/or non-equilibrium pro-cessing techniques such as air plasma spraying (APS), high velocity oxy-fuel (HVOF)spraying [15], magnetron sputtering [16] electro-spark deposition [17], and sparkplasma sintering [18] have the capabilities to retain or form the amorphous structurein the coatings. Although attractive, these techniques are not bereft of limitations relatedto the quality of the coatings such as weak interfacial bonding, partial devitrification,and other undesirable phase transformation. Laser cladding, where preplaced amor-phous powder is remelted and rapidly solidified on the substrate, appears to be bettersuited for the deposition of thick amorphous alloy coatings for tribological applications[19].

Recently, iron-based amorphous alloy with composition Fe48Cr15Mo14Y2C15B6 hasemerged as a promising coating material. The ease of production owing to its high glassforming ability attributed to the presence of yttrium, coupled with excellent wear andcorrosion resistance [20] makes it an excellent choice for the coatings applications. Inspite of numerous attempts to utilize the properties of this amorphous alloy composi-tion, one of the major drawbacks encountered is that of compositional dilution frompartial substrate melting which inhibits the formation of a fully amorphous structure inthe coating layer [21]. An attempt to circumvent this problem was made by Ye et al.,albeit with a different composition of iron-based amorphous alloy (Fe-Cr-Mo-W-Mn-C-Si-B) deposited on 304 L stainless steel substrate using laser direct deposition [14],wherein XRD evidence showed an increase in the fraction of amorphous phase as thenumber of layers deposited increased from 1 to 6. However, further investigations areneeded to systematically characterize the development of surface microstructure andwear properties with the increase in the number of coating layers. In the present work,1, 2 and 3 layered Fe-based amorphous coatings of composition Fe48Cr15Mo14Y2C15B6

were applied on AISI 1018 steel via laser cladding. The results of systematic investi-gations on phase evolution, microstructure development, and wear behavior withincreasing number of amorphous coating layers are presented.

232 Lasers Manuf. Mater. Process. (2015) 2:231–241

Experimental Procedure

The amorphous alloy powders of composition Fe48Cr15Mo14Y2C15B6 (at.%) andparticle size of about 15-53 μm were used for laser cladding experiments. Rect-angular plates of AISI 1018 steel substrates with dimensions approximately30 mm×20 mm×3 mm were ground on 400-grit SiC pads, cleaned and degreasedwith acetone, and dried by alcohol prior to laser cladding. The amorphous alloypowder was mixed in a water soluble organic binder to form thick slurry that wassubsequently spray coated on the substrate to the thicknesses of 100–125 μm. Theas-sprayed substrates were subsequently dried in air for a day prior to lasercladding. A continuous wave CO2 laser with laser power of 950 W was irradiatedon the dried spray coated substrates. The laser cladding was performed by layingparallel tracks with the working distance of 15 mm (laser beam diameter of2.15 mm), scanning at a linear speed of 20 mm/s, and track overlap of 0.6 mm.For multi-layered (2 and 3 layer) cladding, the previously clad substrates werecooled, and the subsequent layer of cladding was deposited with the similar laserprocessing parameters as the single layer cladding. The phases in the laser cladsamples were characterized using a x-ray diffractometer (BRUKER AXS Inc,Madison, WI) operating with Cu-Kα radiation (λ=1.54178 Å). The diffractionangle (2θ) was varied between 20° and 80°. The cross sections of the laser cladsamples were prepared by polishing with SiC polishing pads (in the order ofincreasing grit numbers: 400, 600, 800, and 1200 grit) followed by polishing withalumina slurry (5 μm and 0.5 μm) on a micro-cloth. The polished samples werethen etched with 2 % Nital for 15 s to reveal the microstructure. Vickers micro-hardness tester (Clark Instruments) was used at an operating load of 300 g tomeasure the hardness along the depth of the laser clad substrates. Wear tests wereperformed using a ball-on-disc-tribometer (Nanovea, Irvine, CA) with a normalload of 20 N and a sliding velocity of 100 rpm. A 6-mm diameter aluminum oxide(Al2O3) ball was used as a counter body to create a wear track of 4 mm diameteron the sample surface. The weight loss was recorded at an interval of 10 min fortotal test duration of 40 min. The wear tracks were also made with a normal loadof 30 N for 12 h to make them suitable for observation under SEM. Surfaceprofiles of the worn tracks were recorded using a 3D optical profilometer(Nanovea, Irvine, CA). The volume wear loss was calculated by multiplying theaverage area of cross-section of the wear groove by the length of the wear track. Ascanning electron microscope (JEOL Ltd, Tokyo, Japan) was used to characterizethe polished as well as worn surfaces of the coated samples. Thickness of coatingslayers was measured using an image analysis software by taking at least 12measurements, and mean values with standard deviation are reported.

Results and Discussion

Analysis of Phases

The XRD spectrum of the as-received amorphous powder depicted in Fig. 1ashows a diffused, broad peak in the 2θ range of 40° to 46°, indicative of fully

Lasers Manuf. Mater. Process. (2015) 2:231–241 233

amorphous structure of the alloy. The DSC scan of the amorphous powder withsimilar composition exhibited a glass transition at 575 °C that precedes twoexothermic crystallization peaks [21]. These observations confirm the glassynature of the as-received powder, thereby serving our aforesaid motivation ofthe development of amorphous coatings on steel substrates by laser cladding.Figure 1b presents the XRD spectra of the laser surface cladded AISI 1018 steelwith one, two and three layers of Fe48Cr15Mo14Y2C15B6 alloy coatings. Eachspectrum exhibits a diffused peak in the same 2θ range as that of the as-receivedpowder, indicating preservation of amorphous phase in all the cladded layers.Additionally, the XRD spectra from laser clad coatings show sharper peakscorresponding to the formation of various crystalline phases. The high affinity

20 30 40 50 60 70 80

).u.

a( ytisn

etnI

2 (degrees)

(a)

20 30 40 50 60 70 80

��

��

��

��� **�

** �

*

3 Layers

2 Layers

).u.

a( ytisn

etnI

2(degrees)

1 Layer

* Y2O

3

�Fe3C

�(Fe,Cr)23

C6

�(Fe,Cr)7C

3

(b)

Fig. 1 XRD spectra of a as-received amorphous alloy powder, and b top surface of laser surface claddedsamples with different number of layers of amorphous alloy coatings

234 Lasers Manuf. Mater. Process. (2015) 2:231–241

of yttrium towards oxygen results in a strong Y2O3 peak in each of the spectra.Yttrium is known to improve the glass forming ability of the aforesaid Fe-basedbulk metallic glass composition [22], the consumption of which results in thedeterioration of glass forming ability of the remaining composition. Additionally,these oxide particles provide heterogenous nucleation sites in the melt pool whichaids the growth of various crystalline carbide phases like Fe3C, (Fe, Cr)23C6 and(Fe, Cr)7C3. These carbides, otherwise destabilized by the presence of yttrium[23], have also been observed when Fe-based amorphous alloy of the samecomposition was used for laser surface coating of steel substrates [24].

It is noteworthy that although identical carbides have been found in all the samples,the relative amounts of theses phases vary with the number of clad layers in coating.The growth of crystalline phases and solidification of the melt pool depend upon anumber of factors. The melt pool formed during laser cladding of a single layer ofcoating is in direct contact with the substrate, and partial melting of substrate isexpected to cause significant dilution of the melt pool. On the other hand, the meltpool in each subsequent layers of multi-layered clads solidify on the previously cladamorphous alloy coating without further melting of the substrate. The multi-layer cladcoatings are likely to exhibit significantly lower dilution because the compositionaleffects due to partial melting of substrate are distributed in larger volume of the cladmaterial. Dissimilar thermal properties of the substrate and powder [25, 26] and thevarying extent of dilution of the substrate lead to different cooling rates experienced bythe single and multilayer (2 and 3) coatings. Moreover, during solidification, theleading front at a nucleation site gradually discards solute into the melt thereby makingit richer in and itself devoid of the same. This coupled with convective flow in the meltpool and dilution from the substrate results in considerable redistribution of solute.These result in varying amounts of carbides formed in the coatings with differentnumber of layers.

400 µm 200 µm

(a) (b) (c)

200 µm

Fig. 2 Cross-sectional SEM micrographs of samples laser cladded with a one, b two and c three layers ofamorphous alloy

Table 1 Thickness of coatings on samples laser cladded with one, two, and three layers of amorphous alloy

Cladding Minimum thickness(μm)

Maximum thickness(μm)

Mean thickness(μm)

Standard Deviation(μm)

1 Layer 115.0 199.6 166.5 25.4

2 Layers 327.8 422.5 372.8 33.4

3 Layers 369.6 470.5 430.5 29.4

Lasers Manuf. Mater. Process. (2015) 2:231–241 235

Microstructure Evolution

The SEM micrographs of the samples laser cladded with one, two, and threelayers of Fe48Cr15Mo14Y2C15B6 amorphous alloy coatings are presented in Fig. 2.The figure shows that the thickness of the coatings, although not uniform alongthe cross section, increases progressively with increasing number of clad layers inthe coatings. The details of the thickness of the cladded layers are enumerated inTable 1. Figure 2a shows that while a single layer of powder results in relativelysound cladding, the multi-layer clad coatings exhibit conspicuous cracks and voidsalong their cross sections (Fig. 2b-c). The regions in the cross sections of thesamples laser cladded with two and three layers of coatings where considerablecrystallization has taken place are depicted in Fig. 3 along with the correspondinghigh magnification images in the insets. The interaction of lasers with materialsoften generate very high temperatures followed by rapid cooling (cooling rate upto 105 K/s) that results in considerable residual stresses [21] in the coated samples.The disparate coefficients of thermal expansion of the substrate and crystallinecarbides formed during solidification, as observed from the XRD spectra

Voids

100 µm

CrackVoid

100 µm

10 µm 20 µm

(a) (b)

Fig. 3 High magnification SEM micrographs of the cross sections of the samples laser cladded with a twoand b three layers of amorphous alloy coatings

0 100 200 300 400 500 600 700 800 900100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

VH(

sse

ndr

aH

0.3

)

Distance (m)

- - - - Substrate 1 Layer 2 Layers 3 Layers As sintered

powder

Fig. 4 Hardness profiles along the depth of samples laser cladded with one, two, and three layers ofamorphous alloy coatings. Broken lines represent corresponding hardness values for the substrate and as-sintered amorphous alloy powder

236 Lasers Manuf. Mater. Process. (2015) 2:231–241

discussed previously, also contribute to the above. Such surface irregularities werealso observed elsewhere [19].

Microhardness

The hardness profiles along the depth of the samples laser cladded with one, twoand three layers of Fe48Cr15Mo14Y2C15B6 amorphous alloy coatings are presentedin Fig. 4. The hardness values for the substrate (~160 VHN) and the as-sinteredFe48Cr15Mo14Y2C15B6 alloy powder (1200 VHN) [27] are also indicated in thefigure. Considerable improvement of the surface hardness of the coatings isobserved compared to that of the steel substrate. While samples laser claddedwith one and two layers of amorphous coating exhibit comparable values ofhardness at the surface (~650 VHN) the addition of a third layer almost doublesit to about 1100 VHN.

In addition to the existence of a composite microstructure of hard crystallinecarbides dispersed in an amorphous matrix in the coatings, as noted previously in theSEM photographs (Fig. 3), hardness of amorphous coatings is also affected bymedium-range-ordering (MRO) colonies that are formed due to heating of previousclad layer during surface melting in multi-layered coatings [28, 29]. These coloniesoppose shear band propagation resulting in increased hardness of the amorphous

0 10 20 30 400

50

100

150

200

250

300

350

)g

m(ss

oL

th

gie

Wevit

alu

mu

C

Time (min)

Substrate 1 Layer 2 Layers 3 Layers

Fig. 5 Cumulative weight loss as a function of sliding time for wear tests performed on the substrate and laserclad amorphous alloy coatings

200 µm 200 µm 200 µm

(a) (b) (c)

Fig. 6 SEMmicrographs from worn surfaces of samples laser cladded with a one, b two, and c three layers ofamorphous alloy coatings

Lasers Manuf. Mater. Process. (2015) 2:231–241 237

matrices. In contrast, dilution of solute from the amorphous matrix reduces its hardness.Apart from the reducing extent of dilution, the gradually diminishing hardness profilessuggest a considerable drop in volume fraction of carbides and density of MROcolonies along the depth of all the laser cladded samples. The simultaneous effect ofthese factors results in all the hardness values being less than that of the as-sinteredamorphous powder. The depth of hardening also increases from about 200 μm for 1layer to 250 μm for 2 layers and 400 μm for 3 layers of powder due to an increase inthe thickness of coatings as well as melting of the substrate to greater depths asdiscussed previously.

100 µm 100 µm 100 µm

Fig. 7 High magnification SEM micrographs from the worn surfaces of sample laser cladded with threelayers of amorphous alloy coatings

0.0 0.5 1.0 1.5

-35

-30

-25

-20

-15

-10

-5

0

De

pth

(m

)

Distance (mm)

28.47 m

(a)0.0 0.5 1.0 1.5

-35

-30

-25

-20

-15

-10

-5

0

De

pth

(m

)

Distance (mm)

29.78 m

(b)

0.0 0.5 1.0 1.5 2.0

-45-40-35-30-25-20-15-10

-50

De

pth

(m

)

Distance (mm)

39.16 m

(c)

µ µ

µ

µµ

µ

Fig. 8 Representative surface profiles from worn tracks of samples laser cladded with a one, b two, and cthree layers of amorphous alloy coatings. The dashed lines represent the location of the surface

238 Lasers Manuf. Mater. Process. (2015) 2:231–241

Wear Analysis

Figure 5 shows the cumulative wear weight loss of the samples coated with one, twoand three layers of Fe48Cr15Mo14Y2C15B6 alloy coatings. The wear weight loss data forthe untreated substrate was also plotted for comparison. It can be seen that only thesample having a single layer of coating offers improved wear resistance as compared tothe substrate. The amorphous coatings with two layers exhibited the comparable weightloss with that of the substrate. The laser clad samples with three layered coatings showweight loss comparable to that for the other two coatings and the substrate in the earlystages of the wear test (i.e., about 10 min. in the wear test). However, as the testprogresses, the three layered coatings undergo a drastically higher wear weight losscompared to the other coatings. As can be seen from the SEM micrographs the wornsurfaces of the coatings laser cladded with one and two layers ofFe48Cr15Mo14Y2C15B6 amorphous alloy are quite even and featureless (Fig. 6a andb) while that with three layered coatings (Fig. 6c) shows considerable delamination andcracking. In addition to the cracking and delamination, the oxidative wear also appearsto be a contributing mechanism of the wear in the laser clad amorphous coatings. Thepresence of elements with high affinity for oxygen in the amorphous alloys along withthe high temperature generated during wear process are likely to result in surfaceoxidation and associated cracking. Figure 7 shows the dark patches, as previouslyreported [30], on the wear surface of three layered laser clad coatings indicative ofoxidative wear mechanism. Based on detailed EDS analysis, the oxidative wear of thebulk amorphous alloys has been reported for HVOF sprayed [31] and spark plasmasintered [30] amorphous coatings of similar compositions.

To have more insight into the wear process, surface profiles of the wear tracks wereobtained, and the maximum depth of wear track and volume of material removed weremeasured at different locations. The representative profiles of wear tracks and wearvolume loss data for multilayered coatings are shown in Figs. 8 and 9, respectively. Inagreement with Fig. 5, the amount of material removed (wear material loss) in the case

1 2 30.0

0.1

0.2

0.3

0.4

mm(

hg

uort

ra

ew

fo

em

ulo

V3)

Number of layers

Fig. 9 Average volume of material removed (wear volume loss) from samples laser cladded with a one, btwo, and c three layers of amorphous alloy coatings

Lasers Manuf. Mater. Process. (2015) 2:231–241 239

of coatings laser clad with one and two layers of amorphous alloy are comparable,while the wear loss with three layered coatings is considerably greater as seen from thetrends of maximum wear depth and volume of material removed (Figs. 8 and 9).

Conclusions

The coatings of Fe48Cr15Mo14Y2C15B6 amorphous alloy were applied on AISI 1018steel substrates employing laser cladding technique. Multi-layered (with two and threelayers) coatings were applied to restrict the extent of dilution of elements in the coatingas well as across the substrate-coating interface. Although the multi-layered coatingscould not preserve fully amorphous structure, with the formation of varying amounts ofcrystalline carbide phases due to solute redistribution during solidification, considerableimprovement in the surface hardness as compared to that of the substrate was observed.In the case of the coatings laser cladded with three layers of amorphous alloy, hardnessvalues almost similar to that reported for as-sintered powder could be achieved alongwith an increase in the depth of hardening. The hardness profiles with graduallydiminishing hardness were seen due to reduction in the volume of carbides and thermaleffects with increasing depth of the coatings. Wear in the multi-layered coatings occurspredominantly due to cracking and delamination of the layers possibly along withcontributing surface oxidation. These mechanisms result in accelerated material remov-al in the coatings laser clad with three layers of amorphous alloy, while the coatingswith single layer offered better resistance than the substrate. The maximum depth ofwear track and volume of material removed were also comparable for the coatings laserclad with one and two layers while that with three layers was considerably higher.

Acknowledgments This material is based upon work supported by the National Science Foundation underGrant No. CMMI 0969255.

References

1. Wesley, W.A., Copson, H.R.: Coating steel with nickel by immersion in nickel chloride solutions. J.Electrochem. Soc. 94, 20–31 (1948)

2. Blum, W., Strausser, P.W.C.: Outdoor exposure tests of electroplated nickel and chromium coatings onsteel and nonferrous metals. J. Res. Natl. Bur. Stand. 24, 443–474 (1940)

3. Blum, W., Strausser, P.W.C., Brenner, A.: Corrosion-protective value of electrodeposited zinc andcadmium coatings on steel. J. Res. Natl. Bur. Stand. 16, 185–212 (1936)

4. Harrison, W.N., Moore, D.G., Richmond, J.C.: Ceramic coatings for high-temperature protection of steel.J. Res. Natl. Bur. Stand. 38, 293–307 (1947)

5. Paul, S., Lu, Q., Harvey, M.D.F.: Mitigating localized corrosion using Thermally Sprayed Aluminum(TSA) coatings on welded 25 % Cr superduplex stainless steel. J. Therm. Spray Technol. 24, 629–636(2015)

6. Pokorny, P., Mastny, L., Sykora, V., Pala, Z., Brozek, V.: Bond strength of plasma sprayed ceramiccoatings on the phosphated steels. Metalurgija 54, 411–414 (2015)

7. Adachi, S., Nakata, K.: Study of bonding strength of plasma-sprayed Ti-Al coating on mild steel substrate.Plasma Process. Polym. 4, S512–S515 (2007)

240 Lasers Manuf. Mater. Process. (2015) 2:231–241

8. Marulanda Arevalo, J.L., Perez Trujillo, F.J., Castaneda, S.I.: Aluminum-silicon coatings on austeniticstainless steel (AISI 304 and 317) deposited by chemical vapor deposition in a fluidized bed. Ingenieria EInvestigacion 34, 5–10 (2014)

9. Inoue, A., Hashimoto, K.: Amorphous and nanocrystalline materials: preparation, properties and appli-cations. Springer, Berlin (2001)

10. Parker, F.T., Spada, F.E., Berkowitz, A.E., Vecchio, K.S., Lavernia, E.J., Rodriguez, R.: Thick amorphousferromagnetic coatings via thermal spraying of spark-eroded powder. Mater. Lett. 48, 184–187 (2001)

11. Fenineche, N.E., Cherigui, M., Aourag, H., Coddet, C.: Structure and magnetic properties study of iron-based thermally sprayed alloys. Mater. Lett. 58, 1797–1801 (2004)

12. Cherigui, M., Feraoun, H.I., Feninehe, N.E., Aourag, H., Coddet, C.: Structure of amorphous iron-basedcoatings processed by HVOF and APS thermally spraying. Mater. Chem. Phys. 85, 113–119 (2004)

13. Andrea Milanti, Microstructural Characteristics and Tribological Behavior, Coatings, (2014)14. Ye, X., Shin, Y.C.: Synthesis and characterization of Fe-based amorphous composite by laser direct

deposition. Surf. Coat. Technol. 239, 34–40 (2014)15. Otsubo, F., Kishitake, K.: Corrosion resistance of Fe-16%Cr-30%Mo-(C, B, P) amorphous coatings

sprayed by HVOF and APS processes. Mater. Trans. 46, 80–83 (2005)16. Chen, L.H., Chen, H.K., Hsieh, C.T., Shih, Y.H., Chen, I.G., Chen, S.Y., Liu, H.P.: Soft magnetic

properties of Co-Fe-Zr-B-Al-O films. J. Appl. Phys. 91, 8450–8452 (2002)17. Liu, D., Gao, W., Li, Z., Zhang, H., Hu, Z.: Electro-spark deposition of Fe-based amorphous alloy

coatings. Mater. Lett. 61, 165–167 (2007)18. Singh, A., Bakshi, S.R., Agarwal, A., Harimkar, S.P.: Microstructure and tribological behavior of spark

plasma sintered iron-based amorphous coatings. Mater. Sci. Eng. a-Struct. Mater. Prop. Microstruct.Process. 527, 5000–5007 (2010)

19. Katakam, S., Santhanakrishnan, S., Dahotre, N.B.: Fe-Based amorphous coatings on AISI 4130 structuralsteel for corrosion resistance. JOM 64, 709–715 (2012)

20. Zhou, Z., Wang, L., Wang, F.-c., Liu, Y.-b.: Formation and corrosion behavior of Fe-based amorphousmetallic coatings prepared by detonation gun spraying. Trans. Nonferrous Metals Soc. China 19, S634–S638 (2009)

21. Basu, A., Sarnant, A.N., Harirnkar, S.P., Majumdar, J.D., Manna, I., Dahotre, N.B.: Laser surface coatingof Fe-Cr-Mo-Y-B-C bulk metallic glass composition on AISI 4140 steel. Surf. Coat. Technol. 202, 2623–2631 (2008)

22. A. Bouchareb, B. Bendjemil, R. Piccin, M. Baricco, Influence of Rare-Earth Substitution for Iron inFeCrMoCB Bulk Metallic Glasses, Chinese Physics Letters, 27 (2010)

23. Ha, H.M., Payer, J.H.: Devitrification of Fe-Based amorphous metal SAM 1651: a structural andcompositional study. Metall. Mater. Trans. a-Phys. Metall. Mater. Sci. 40A, 2519–2529 (2009)

24. Katakam, S., Hwang, J.Y., Paital, S., Banerjee, R., Vora, H., Dahotre, N.B.: In situ laser synthesis of fe-based amorphous matrix composite coating on structural steel. Metall. Mater. Trans. a-Phys. Metall.Mater. Sci. 43A, 4957–4966 (2012)

25. Inoue, A., Arnberg, L., Oguchi, M., Backmark, U., Backstrom, N., Masumoto, T.: Preparation of Fe-Cr-Mo-C amorphous powders and microstructure and mechanical-properties of their hot-pressed products.Mater. Sci. Eng. 95, 101–114 (1987)

26. Pantsar, H., Kujanpaa, V.: Diode laser beam absorption in laser transformation hardening of low alloysteel. J. Laser Appl. 16, 147–153 (2004)

27. Singh, A.K., Alavi, S.H., Paital, S.R., Dahotre, N.B., Harimkar, S.P.: Structural relaxation andnanocrystallization-induced laser surface hardening of Fe-Based bulk amorphous alloys. JOM 66,1080–1087 (2014)

28. H.S. Chou, J.C. Huang, L.W. Chang, T.G. Nieh, Structural relaxation and nanoindentation response in Zr-Cu-Ti amorphous thin films, Applied Physics Letters, 93 (2008)

29. Murali, P., Ramamurty, U.: Embrittlement of a bulk metallic glass due to sub-T-g annealing. Acta Mater.53, 1467–1478 (2005)

30. Singh, A., Paital, S.R., Andapally, A., Dahotre, N.B., Harimkar, S.P.: Densification behavior and wearresponse of spark plasma sintered iron-based bulk amorphous alloys. Adv. Eng. Mater. 14, 400–407(2012)

31. Zhang, C., Liu, L., Chan, K.C., Chen, Q., Tang, C.Y.: Wear behavior of HVOF-sprayed Fe-basedamorphous coatings. Intermetallics 29, 80–85 (2012)

Lasers Manuf. Mater. Process. (2015) 2:231–241 241