The dual effect of grain size on the strain hardening behaviors of Ni-Co-Cr-Fe high entropy alloys

doi:10.1016/j.jmst.2022.06.001

Abstract

Abstract:

It has been well documented that grain size plays a critical role in the strain hardening behaviors of metals and alloys. However, the influence of grain size on the strain hardening of high entropy alloys (HEAs) was not fully understood. Here, we report that the grain size not only affects the twinning-induced plasticity (TWIP) effect but also changes the dislocation-based deformation behaviors of face-centered-cubic (fcc) HEAs significantly. The strain hardening and deformation micro-mechanisms of NiCoCrFe and Ni₂CoCrFe were investigated using electron channeling contrast (ECCI) analysis. Our results showed that Ni₂CoCrFe exhibits a typical three-stage strain hardening behavior and NiCoCrFe shows the fourth stage at high strains due to the TWIP effect. For both NiCoCrFe and Ni₂CoCrFe, the increase of grain size leads to a transition of dislocation glide from wavy to planar mode, resulting in a low value and the recovery of strain hardening rate in stage II. The large-grain NiCoCrFe showed a higher strain hardening rate in stage IV due to the promoted deformation twinning. Combining the strain hardening behaviors of the TWIP-NiCoCrFe and the mechanically stable Ni₂CoCrFe, we showed that the grain size influences the stage II hardening through tuning dislocation glide mode and the stage IV by tailoring deformation twinning activity of the Ni-Co-Cr-Fe HEAs. The grain size just affects stages I and III slightly in the current cases. These findings will also provide some insights into the understanding of strain hardening behaviors in other face-centered-cubic HEAs.

Key words: Strain hardening, Deformation mechanism, Grain size, Dislocation glide mode

Xiaorong Liu, Sihan Jiang, Jianlin Lu, Jie Wei, Daixiu Wei, Feng He. The dual effect of grain size on the strain hardening behaviors of Ni-Co-Cr-Fe high entropy alloys[J]. J. Mater. Sci. Technol., 2022, 131: 177-184.

Figures/Tables 12

Fig. 1. Microstructures and tensile properties of NiCoCrFe with different grain sizes. (a-c) BSE images for the NiCoCrFe HEAs with grain sizes of 11, 84, and 125 μm, (d) tensile stress-strain curves of the NiCoCrFe HEAs, and (e) strain hardening rate vs true strain plots for the curves in (d).

Fig. 2. Deformation substructures of fine-grain NiCoCrFe. (a) ECCI images at ～10% strain, (b) ECCI images at ～30% strain, and (c) ECCI images at ～50% strain.

Fig. 3. Deformation substructures of small-grain NiCoCrFe. (a) ECCI images at ～10% strain, (b) ECCI images at ～30% strain, and (c) ECCI images at ～50% strain.

Fig. 4. Deformation substructures of large-grain NiCoCrFe. (a) ECCI images at ～10% strain, (b) ECCI images at ～30% strain, and (c) ECCI images at ～50% strain.

Fig. 5. EBSD analysis for the deformation mechanisms of NiCoCrFe HEAs with different grain sizes at a strain of ～50%. (a-c) IQ maps of the fine, small, and large-grain samples, (d-f) inverse pole figure (IPF) maps of the fine, small, and large-grain samples, and (g-i) KAM maps of the fine, small, and large-grain samples.

Fig. 6. Tensile properties of Ni2CoCrFe with different grain sizes. (a) Tensile stress-strain curves and (b) strain hardening rate vs true strain plots for the curves in (a).

Fig. 7. Deformation substructures of fine-grain NiCoCrFe. (a) ECCI images at ～10% strain, (b) ECCI images at ～20% strain, and (c) ECCI images at ～30% strain.

Fig. 8. Deformation substructures of large-grain Ni2CoCrFe. (a) ECCI images at ～10% strain, (b) ECCI images at ～20% strain, and (c) ECCI images at ～30% strain.

Fig. 9. Comparison of strain hardening behaviors of the NiCoCrFe (～65 μm) and Ni2CoCrFe (～84 μm) HEAs with similar grain sizes. (a) Stress-strain curves and (b) strain hardening rate vs. true strain plots.

Fig. 10. EBSD analysis of the fractured NiCoCrFe and Ni2CoCrFe with similar grain size; (a1-a3) IQ, IPF, and KAM maps for NiCoCrFe and (b1-b3) IQ, IPF, and KAM maps for Ni2CoCrFe.

Table 1. Statistical results of the twining behaviors of NiCoCrFe based on ECCI results.

Grain sizec (µm)	11			84			125
Strain (%)	10	30	50	10	30	50	10	30	50
Percentage of twined grains (%)	0	13	22	0	79	100	0	100	100

Fig. 11. Initial microstructures of the Ni2CoCrFe HEA with different grain sizes. (a) ～17 μm and (b) ～172 μm.

References 38

[1]	D.B. Miracle, O.N. Senkov, Acta Mater. 122 (2017) 448-511. DOI URL
[2]	B. Cai, B. Liu, S. Kabra, Y.Q. Wang, K. Yan, P.D. Lee, Y. Liu, Acta Mater. 127 (2017) 471-480. DOI URL
[3]	D. Choudhuri, B. Gwalani, S. Gorsse, M. Komarasamy, S.A. Mantri, S.G. Srini-vasan, R.S. Mishra, R. Banerjee, Acta Mater. 165 (2019) 420-430. DOI
[4]	W.J. Lu, C.H. Liebscher, F.K. Yan, X.F. Fang, L.L. Li, J.J. Li, W.Q. Guo, G. Dehm, D. Raabe, Z.M. Li, Acta Mater. 185 (2020) 218-232. DOI URL
[5]	J. Miao, C.E. Slone, T.M. Smith, C. Niu, H. Bei, M. Ghazisaeidi, G.M. Pharr, M.J. Mills, Acta Mater. 132 (2017) 35-48. DOI URL
[6]	J. Su, D. Raabe, Z.M. Li, Acta Mater. 163 (2019) 40-54. DOI URL
[7]	Y.Q. Wang, B. Liu, K. Yan, M.S. Wang, S. Kabra, Y.L. Chiu, D. Dye, P.D. Lee, Y. Liu, B. Cai, Acta Mater. 154 (2018) 79-89. DOI URL
[8]	E.P. George, W.A. Curtin, C.C. Tasan, Acta Mater. 188 (2020) 435-474. DOI URL
[9]	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. DOI URL
[10]	Q.Q. Ding, Y. Zhang, X. Chen, X.Q. Fu, D.K. Chen, S.J. Chen, L. Gu, F. Wei, H.B. Bei, Y.F. Gao, M.R. Wen, J.X. Li, Z. Zhang, T. Zhu, R.O. Ritchie, Q. Yu, Na-ture 574 (2019) 223-227.
[11]	F. He, D. Chen, B. Han, Q.F. Wu, Z.J. Wang, S.L. Wei, D.X. Wei, J.C. Wang, C.T. Liu, J.J. Kai, Acta Mater. 167 (2019) 275-286. DOI URL
[12]	F. He, Z.S. Yang, S.F. Liu, D. Chen, W.T. Lin, T. Yang, D.X. Wei, Z.J. Wang, J.C. Wang, J.J. Kai, Int. J. Plast. 144 (2021) 103022.
[13]	R.W. Armstrong, Mater. Trans. 55 (2014) 2-12. DOI URL
[14]	A.W. Thompson, Acta Metall. 25 (1977) 83-86. DOI URL
[15]	T. Tabata, K. Takagi, H. Fujita, Trans. Jpn. Inst. Met. 16 (1975) 569-579. DOI URL
[16]	T.L. Johnston, C.E. Feltner, Metall. Mater. Trans. B 1 (1970) 1161.
[17]	P. Asghari-Rad, P. Sathiyamoorthi, J.W. Bae, J. Moon, J.M. Park, A. Zargaran, H.S. Kim, Mater. Sci. Eng. A 744 (2019) 610-617. DOI URL
[18]	S. Yoshida, T. Bhattacharjee, Y. Bai, N. Tsuji, Scr. Mater. 134 (2017) 33-36. DOI URL
[19]	W.H. Liu, Y. Wu, J.Y. He, T.G. Nieh, Z.P. Lu, Scr. Mater. 68 (2013) 526-529. DOI URL
[20]	S.J. Sun, Y.Z. Tian, H.R. Lin, X.G. Dong, Y.H. Wang, Z.J. Wang, Z.F. Zhang, J. Alloy. Compd. 806 (2019) 992-998. DOI
[21]	S.W. Wu, G. Wang, J. Yi, Y.D. Jia, I. Hussain, Q.J. Zhai, P.K. Liaw, Mater. Res. Lett. 5 (2017) 276-283. DOI URL
[22]	S.J. Sun, Y.Z. Tian, H.R. Lin, H.J. Yang, X.G. Dong, Y.H. Wang, Z.F. Zhang, Mater. Sci. Eng. A 712 (2018) 603-607. DOI URL
[23]	Z. Li, C.C. Tasan, K.G. Pradeep, D. Raabe, Acta Mater. 131 (2017) 323-335. DOI URL
[24]	M.A. Meyers, O. Vöhringer, V.A. Lubarda, Acta Mater. 49 (2001) 4025-4039. DOI URL
[25]	B. Wang, H.Y. He, M. Naeem, S. Lan, S. Harjo, T. Kawasaki, Y.X. Nie, H.W. Kui, T. Ungár, D. Ma, A.D. Stoica, Q. Li, Y.B. Ke, C.T. Liu, X.L. Wang, Scr. Mater. 155 (2018) 54-57. DOI URL
[26]	S. Wei, C.C. Tasan, Acta Mater. 200 (2020) 992-1007. DOI URL
[27]	F. He, S.L. Wei, J.L. Cann, Z.J. Wang, J.C. Wang, C.C. Tasan, Acta Mater. 220 (2021) 117314.
[28]	D.X. Wei, X.Q. Li, S. Schönecker, J. Jiang, W.M. Choi, B.J. Lee, H.S. Kim, A. Chiba, H. Kato, Acta Mater. 181 (2019) 318-330. DOI URL
[29]	F. He, Z.J. Wang, Q.F. Wu, J.J. Li, J.C. Wang, C.T. Liu, Scr. Mater. 126 (2017) 15-19. DOI URL
[30]	S.J. Zhao, G.M. Stocks, Y.W. Zhang, Acta Mater. 134 (2017) 334-345. DOI URL
[31]	Z. Wu, H. Bei, G.M. Pharr, E.P. George, Acta Mater. 81 (2014) 428-441. DOI URL
[32]	U.F. Kocks, H. Mecking, Prog. Mater. Sci. 48 (2003) 171-273. DOI URL
[33]	D. Kuhlmann-Wilsdorf, Philos. Mag. A 79 (1999) 955-1008. DOI URL
[34]	S. Zaefferer, N.N. Elhami, Acta Mater. 75 (2014) 20-50. DOI URL
[35]	B. Bay, N. Hansen, D.A. Hughes, D. Kuhlmann-Wilsdorf, Acta Metall. Mater. 40 (1992) 205-219. DOI URL
[36]	E. El-Danaf, S.R. Kalidindi, R.D. Doherty, Metall. Mater. Trans. A 30 (1999) 1223-1233. DOI URL
[37]	Y.Z. Tian, L.J. Zhao, S. Chen, A. Shibata, Z.F. Zhang, N. Tsuji, Sci. Rep. 5 (2015) 16707. DOI PMID
[38]	C.L. Yang, Z.J. Zhang, T. Cai, P. Zhang, Z.F. Zhang, Sci. Rep. 5 (2015) 15532. DOI PMID