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

• DOI: 10.1073/pnas.1919136117
• Publication Date: 2020-06-30T00:37:55Z
• Authors: Bing Chen; Suzhi Li; Hongxiang Zong; Xiangdong Ding; Jun Sun; Evan Ma
• Keywords: Cubic crystal system; High-Entropy Alloys

Atomistic simulations of dislocation mobility reveal that body-centered cubic (BCC) high-entropy alloys (HEAs) are distinctly different from traditional BCC metals. HEAs 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 as the rate-limiting mechanism. Edge dislocations encounter a similar activated process nanoscale segment detrapping, comparable activation barrier. As result, edge and hence their contribution to strength, becomes dislocations.