Phase stabilities of high entropy alloys

doi:10.1016/j.scriptamat.2019.12.041

Scripta Materialia

Volume 179, 1 April 2020, Pages 40-44

https://doi.org/10.1016/j.scriptamat.2019.12.041 Get rights and content

Abstract

A perturbation model is used to evaluate the phase stabilities of high entropy alloys. The calculation results can successfully predict the phase stabilities of many high entropy alloys and shows that stable single phase high entropy alloys are rare. The effect of increased entropy cannot balance the fast-increased driving force for the formation of intermetallics. As the temperature increases, the stabilities of solid solutions will increase and the portion of single-phase alloys will expand. The model we propose provides a new paradigm to understand the phase stabilities of high entropy alloys.

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Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

This work was supported by the National Natural Science Foundation of China [grant numbers 51771096 and 51871129]. The authors are grateful to Dr. Na Chen, Dr. Qi Zhang, Dr. Jiajia Si, Miss Shuhang Yang, Dr. Shuangqin Chen and Mr. Xinglong Yang for fruitful discussions. H. L. and Y.S. are also grateful to the support of Tsinghua National Laboratory for Information Science and Technology for the thermodynamic calculations.

References (45)

O.N. Senkov et al.
Intermetallics
(2011)
Z. Han et al.
Mater. Sci. Eng. A
(2018)
N.A.P.K. Kumar et al.
Acta Mater.
(2016)
L. Yang et al.
J. Mater. Sci. Technol.
(2019)
K.V. Yusenko et al.
Scr. Mater.
(2017)
E.J. Pickering et al.
Scr. Mater.
(2016)
F. Otto et al.
Acta Mater.
(2016)
X. Yang et al.
Mater. Chem. Phys.
(2012)
Y. Wang et al.
Acta Mater.
(2018)
R. Chen et al.
Acta Mater.
(2018)

W. Huang et al.

Acta Mater.

(2019)

C. Wen et al.

Acta Mater.

(2019)

N. Islam et al.

Comput. Mater. Sci.

(2018)

S. Curtarolo et al.

Comput. Mater. Sci.

(2012)

S. Curtarolo et al.

Comput. Mater. Sci.

(2012)

F. He et al.

Scr. Mater.

(2017)

M.-H. Chuang et al.

Acta Mater.

(2011)

P. Jinhong et al.

Mater. Sci. Eng. A

(2012)

N.D. Stepanov et al.

J. Alloys Compd.

(2015)

J.-H. Pi et al.

J. Alloys Compd.

(2011)

K. Zhang et al.

Mater. Sci. Eng. A

(2009)

J.Y. He et al.

Acta Mater.

(2016)

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Phase stabilities of high entropy alloys

Abstract

Graphical abstract

Section snippets

Declaration of Competing Interest

Acknowledgments

Intermetallics

Mater. Sci. Eng. A

Acta Mater.

J. Mater. Sci. Technol.

Scr. Mater.

Scr. Mater.

Acta Mater.

Mater. Chem. Phys.

Acta Mater.

Acta Mater.

Acta Mater.

Acta Mater.

Comput. Mater. Sci.

Comput. Mater. Sci.

Comput. Mater. Sci.

Scr. Mater.

Acta Mater.

Mater. Sci. Eng. A

J. Alloys Compd.

J. Alloys Compd.

Mater. Sci. Eng. A

Acta Mater.