Unusual activated processes controlling dislocation motion in body-centered-cubic high-entropy alloys

Atomistic simulations of dislocation mobility reveal that bodycentered cubic (BCC) high-entropy alloys (HEAs) are distinctly different from traditional BCC metals. HEAs are concentrated solutions in which composition fluctuation is almost inevitable. The resultant inhomogeneities, while locally prom...

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Published inProceedings of the National Academy of Sciences - PNAS Vol. 117; no. 28; pp. 16199 - 16206
Main Authors Chen, Bing, Li, Suzhi, Zong, Hongxiang, Ding, Xiangdong, Sun, Jun, Ma, Evan
Format Journal Article
LanguageEnglish
Published Washington National Academy of Sciences 14.07.2020
Subjects
Alloys
BCC metals
Dislocation mobility
Edge dislocations
High entropy alloys
Metals
Mobility
Nucleation
Physical Sciences
Screw dislocations
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Summary:Atomistic simulations of dislocation mobility reveal that bodycentered cubic (BCC) high-entropy alloys (HEAs) are distinctly different from traditional BCC metals. HEAs are concentrated solutions in which composition fluctuation is almost inevitable. The resultant inhomogeneities, while locally promoting kink nucleation on screw dislocations, trap them against propagation with an appreciable energy barrier, replacing kink nucleation as the rate-limiting mechanism. Edge dislocations encounter a similar activated process of nanoscale segment detrapping, with comparable activation barrier. As a result, the mobility of edge dislocations, and hence their contribution to strength, becomes comparable to screw dislocations.
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Edited by Alexis T. Bell, University of California, Berkeley, CA, and approved May 31, 2020 (received for review November 1, 2019)
Author contributions: S.L. and E.M. designed research; B.C. and S.L. performed research; S.L. and H.Z. contributed new reagents/analytic tools; B.C., S.L., X.D., J.S., and E.M. analyzed data; and S.L. and E.M. wrote the paper.
ISSN:0027-8424
1091-6490
1091-6490
DOI:10.1073/pnas.1919136117