Role of Static Displacements in Stabilizing Body Centered Cubic High Entropy Alloys

G. D. Samolyuk, Y. N. Osetsky, G. M. Stocks, and J. R. Morris

Phys. Rev. Lett. 126, 025501 – Published 11 January 2021

Abstract

The configurational entropy of high entropy alloys (HEAs) plays little role in the stabilization of one particular crystal structure over another. We show that disorder-induced atomic displacements help stabilize body centered cubic (bcc) structure HEAs with average valences $< 4.7$ . These disorder-induced atomic displacements mimic the temperature-induced vibrations that stabilize the bcc structure of group IV elemental metals at high temperatures. The static displacements are significantly larger than for face centered cubic HEAs, approaching values associated with the Lindemann criterion for melting. Chemical disorder in high entropy alloys have a previously unidentified, nonentropic energy contribution that stabilizes a particular crystalline ground state.

Received 19 May 2020
Accepted 12 November 2020

DOI:https://doi.org/10.1103/PhysRevLett.126.025501

Physics Subject Headings (PhySH)

Crystal structure Crystal symmetry Lattice dynamics Phonons

Transition metal alloys

Density functional theory

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

G. D. Samolyuk^1,*, Y. N. Osetsky¹, G. M. Stocks¹, and J. R. Morris ^2,†

¹Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
²Ames Laboratory, Iowa State University, Ames, Iowa 50011, USA