Probing deformation mechanisms of gradient nanostructured CrCoNi medium entropy alloy

doi:10.1016/j.jmst.2020.03.064

Abstract

Abstract:

The gradient nanostructured medium entropy alloys (MEAs) exhibit a good yielding strength and great plasticity. Here, the mechanical properties, microstructure, and strain gradient in the gradient nanostructured MEA CrCoNi are studied by atomic simulations. The strong gradient stress and strain always occur in the deformed gradient nanograined MEA CrCoNi. The origin of improving strength is attributed to the formation of the 9R phase, deformation twinning, as well as the fcc to hcp phase transformation, which prevent strain localization. A microstructure-based predictive model reveals that the lattice distortion dependent solid-solution strengthening and grain-boundary strengthening dominate the yield strength, and the dislocation strengthening governs the strain hardening. The present result provides a fundamental understanding of the gradient nanograined structure and plastic deformation in the gradient nanograined MEA, which gives insights for the design of MEAs with higher strengths.

Key words: Medium entropy alloy, Gradient nanograined structure, Atomic simulation, Strengthening, Deformation, 9R phase, Deformation twinning, Phase transformation

Jia Li, Li Li, Chao Jiang, Qihong Fang, Feng Liu, Yong Liu, Peter K. Liaw. Probing deformation mechanisms of gradient nanostructured CrCoNi medium entropy alloy[J]. J. Mater. Sci. Technol., 2020, 57: 85-91.

Figures/Tables 7

Fig. 1. TEM image revealing the gradient structure, and schematic image showing the gradient nanostructure after machining [16] (a). The atoms of the GNG MEA CrCoNi are colored based on the atomic type (b) and CNA value (c). Cr, Co, and Ni. Stacking fault energy vs. displacement (d).

Fig. 2. Relationship between the stress and strain (a) and strain hardening rate as a function of strain (b).

Fig. 3. Microstructures at different strains of 2% (a1), 4% (a2), 6% (a3), 8% (a4) and 10 % (a5). The distribution of strain (b1-b5) and stress (c1-c5) at different strains of 2%, 4%, 6%, 8%, and 10 %, respectively.

Fig. 4. The partially-enlarged view of 9R phase (a, d), deformation twinning (b, e), and hcp phase (c, f) at a strain of 8%. Atoms are colored according to the CNA (a-c), and according to the type (d-f). The corresponding regions are marked in Fig. 3(a4) by a black box.

Fig. 5. Schematic of GNG CrCoNi MEA subjected to tensile strain of εxx, where GNG CrCoNi MEA is assumed as multi-phase composite structure of n phases with different grain sizes.

Table 1 Material parameters used in the present model for the GNG CrCoNi MEA.

Parameter	Symbol	Magnitude
Elastic modulus (GPa)	E	179
Shear modulus (GPa)	μ	68.8
Poisson’s ratio	ν	0.3
Magnitude of the Burger vector (nm)	b	0.256
Empirical constant	α	0.33
Taylor factor	M	3.06
Dynamic recovery constant	k₂₀	21.6
Proportionality factor	ψ	0.025
Dynamic recovery constant	m	21.5
Reference strain rate (s^-1)	ε˙0	1
Hall-Petch slope (MP m^1/2)	kHP	0.8
Reference grain size (nm)	de	580

Fig. 6. The separate strengthening contributions in GNG CrCoNi MEA under deformation (a) and dislocation strengthening contribution of GNG CrCoNi MEA with different grain sizes (b).

References 55

[1]	J.W. Yeh, S.K. Chen, S.J. Lin, J.Y. Gan, T.S. Chin, T.T. Shun, C.H. Tsau, S.Y. Chang, Adv. Eng. Mater. 6(2004) 299-303.
[2]	Y. Zhang, T.T. Zuo, Z. Tang, M.C. Gao, K.A. Dahmen, P.K. Liaw, Z.P. Lu, Prog. Mater. Sci. 61(2014) 1-93.
[3]	B. Gludovatz, A. Hohenwarter, D. Catoor, E.H. Chang, E.P. George, R.O. Ritchie, Science 345 (2014) 1153-1158.
[4]	Z. Li, K.G. Pradeep, Y. Deng, D. Raabe, C.C. Tasan, Nature 534 (2016) 227-230.
[5]	O. El-Atwani, N. Li, M. Li, A. Devaraj, J.K.S. Baldwin, M.M. Schneider, E. Martinez, Sci. Adv. 5(2019) 2002.
[6]	Z.F. Lei, X.J. Liu, Y. Wu, H. Wang, S.H. Jiang, S.D. Wang, X.D. Hui, Y.D. Wu, B. Gault, P. Kontis, D. Raabe, L. Gu, Q.H. Zhang, H.W. Chen, H.T. Wang, J.B. Liu, K. An, Q.S. Zeng, T.G. Nieh, Z.P. Lu, Nature 563 (2018) 546-550.
[7]	Z. Zhang, H. Sheng, Z. Wang, B. Gludovatz, Z. Zhang, E.P. George, R.O. Ritchie, Nat. Commun. 8(2017) 14390.
[8]	B. Gludovatz, A. Hohenwarter, K.V. Thurston, H. Bei, Z. Wu, E.P. George, R.O. Ritchie, Nat. Commun. 7(2016) 10602.
[9]	Y. Ma, F. Yuan, M. Yang, P. Jiang, E. Ma, X. Wu, Acta Mater. 148(2018) 407-418.
[10]	F. Otto, A. Dlouhý, C. Somsen, H. Bei, G. Eggeler, E.P. George, Acta Mater. 61(2013) 5743-5755.
[11]	Z.W. Wang, I. Baker, Z. Cai, S. Chen, J. Poplawsky, W. Guo, Acta Mater. 120(2016) 228-239.
[12]	Y. Lu, Y. Dong, S. Guo, L. Jiang, H. Kang, T. Wang, B. Wen, Z. Wang, J. Jie, Z. Cao, H. Ruan, T. Li, Sci. Rep. 4(2014) 6200.
[13]	L. Rogal, D. Kalita, A. Tarasek, P. Bobrowski, F. Czerwinski, J. Alloys. Compd. 708(2017) 344-352.
[14]	Y. Zhao, T. Yang, J. Zhu, D. Chen, Y. Yang, A. Hu, C. Liu, J. Kai, Scr. Mater. 148(2018) 51-55.
[15]	G. Chen, J. Qiao, Z. Jiao, D. Zhao, T. Zhang, S. Ma, Z. Wang, Scr. Mater. 167 (2019) 95-100.
[16]	W. Guo, Z. Pei, X. Sang, J. Poplawsky, S. Bruschi, H. Bei, Acta Mater. 170(2019) 176-186.
[17]	F. Kacher, T. Zhu, O. Pierron, D.E. Spearot, Curr. Opin. Solid State Mater.Sci. 23(2019) 117-128.
[18]	E. Ma, T. Zhu, Mater. Today 20 (2017) 323-331.
[19]	L.A. Zepeda-Ruiz, A. Stukowski, T. Oppelstrup, V.V. Bulatov, Nature 550 (2017) 492-495.
[20]	X. Ke, J. Ye, Z. Pan, J. Geng, M.F. Besser, D. Qu, A. Caro, D. Qu, F. Sansoz, Nat. Mater. 18(2019) 1207-1214.
[21]	J. Li, A.K. Soh, Int. J. Plast. 39(2012) 88-102.
[22]	Q. Ding, X. Fu, D. Chen, H. Bei, B. Gludovatz, J. Li, Z. Zhang, E.P. George, Q. Yu, T. Zhu, R.O. Ritchie, Mater. Today 25 (2019) 21-27.
[23]	J.L. Hou, Q. Li, C.B. Wu, L.M. Zheng, Materials 12 (2019) 1010.
[24]	S. Chen, Z.H. Aitken, Z. Wu, R. Banerjee, Y. Zhang, Mater. Sci. Eng. A 773 (2020), 138873.
[25]	X. Liu, H. Yin, Y. Xu, Materials 10 (2017) 1312.
[26]	W.M. Choi, Y.H. Jo, S.S. Sohn, S. Lee, B.J. Lee, NPJ Comput. Mater. 4(2018) 1.
[27]	Q. Fang, Y. Chen, J. Li, C. Jiang, B. Liu, Y. Liu, P.K. Liaw, Int. J. Plast. 114(2019) 161-173.
[28]	J. Li, H. Chen, S. Li, Q. Fang, Y. Liu, L. Liang, Mater. Sci. Eng. A 760 (2019) 359-365.
[29]	S. Plimpton, J. Comput. Phys. 117(1995) 1-19.
[30]	A. Stukowski, Model. Simul. Mater. Sci. Eng. 18(2009), 015012.
[31]	T.H. Courtney, Mechanical Behavior of Materials, Waveland Press, 2005.
[32]	J. Kacher, B. Eftink, B. Cui, I. Robertson, Curr. Opin. Solid State Mater.Sci. 18 (2014) 227-243.
[33]	N.Q. Vo, R.S. Averback, P. Bellon, S. Odunuga, A. Caro, Phys. Rev. B 77 (2008), 134108.
[34]	W. Wu, B. Wei, S. Ni, Y. Liu, M. Song, Intermetallics 96 (2018) 104-110.
[35]	F. Otto, A. Dlouh ´y, C. Somsen, H. Bei, G. Eggeler, E.P. George, Acta Mater. 61 (2013) 5743-5755.
[36]	S. Chen, H. Oh, B. Gludovatz, S.J. Kim, E.S. Park, Z. Zhang, Q. Yu, Nat. Commun. 11(2020) 1-8.
[37]	H.Y. Diao, R. Feng, K.A. Dahmen, P.K. Liaw, Curr. Opin. Solid State Mater.Sci. 21(2017) 252-266.
[38]	H. Huang, Y. Wu, J. He, H. Wang, X. Liu, K. An, Z. Lu, Adv. Mater. 29(2017), 1701678.
[39]	Y. Koizumi, S. Suzuki, K. Yamanaka, B. Lee, K. Sato, Y. Li, S. Kurosu, H. Matsumoto, A. Chiba, Acta Mater. 61(2013) 1648-1661.
[40]	K. Albe, Y. Ritter, D. Sopu, Mech. Mater. 67(2013) 94-103.
[41]	J. Li, Q. Fang, B. Liu, Y. Liu, Acta Mater. 147(2018) 35-41.
[42]	Y. Estrin, H. Mecking, Acta Metall. 32(1984) 57-70.
[43]	J. Li, W. Lu, S. Chen, C. Liu, Int. J. Plast. 126(2020), 102626.
[44]	H. Jin, J. Zhou, Y. Chen, Mater. Sci. Eng. A 725 (2018) 1-7.
[45]	M. Dao, L. Lu, R. Asaro, J. De Hosson, E. Ma, Acta Mater. 55(2007) 4041-4065.
[46]	L. Zhu, H. Ruan, X. Li, M. Dao, H. Gao, J. Lu, Acta Mater. 59(2011) 5544-5557.
[47]	H. Mecking, U. Kocks, Acta Metall. 29(1981) 1865-1875.
[48]	L. Capolungo, C. Jochum, M. Cherkaoui, J. Qu, Int. J. Plast. 21(2005) 67-82.
[49]	L. Capolungo, M. Cherkaoui, J. Qu, Int. J. Plast. 23(2007) 561-591.
[50]	C. Lee, G. Song, M.C. Gao, R. Feng, P. Chen, J. Brechtl, Y. Chen, K. An, W. Guo, J.D. Poplawsky, S. Li, A.T. Samaei, W. Chen, A. Hu, H. Choo, P.K. Liaw, Acta Mater. 160(2018) 158-172.
[51]	O.N. Senkov, J.M. Scott, S.V. Senkova, D.B. Miracle, C.F. Woodward, J. Alloys. Compd. 509(2011) 6043-6048.
[52]	R. Labusch, Phys. Status Solidi A 41 (1970) 659-669.
[53]	A.R. Denton, N.W. Ashcroft, Phys. Rev. A 43 (1991) 3161-3164.
[54]	T.W. Clyne, P.J. Withers, An Introduction to Metal Matrix Composites, Cambridge University Press, Cambridge, 1995.
[55]	J.D. Zuo, C. He, M. Cheng, K. Wu, Y.Q. Wang, J.Y. Zhang, G. Liu, J. Sun, Acta Mater. 174(2019) 279-288.