Journal
ACTA MATERIALIA
Volume 234, Issue -, Pages -Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.actamat.2022.118022
Keywords
Potential energy landscape; High-entropy alloys; Short-range order; Screw dislocation
Funding
- Henry Samueli School of Engineering, University of California, Irvine
- U.S. Department of Energy (DOE), Office of Basic Energy Sciences [DE-SC0022295]
- U.S. Department of Energy (DOE) [DE-SC0022295] Funding Source: U.S. Department of Energy (DOE)
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This study constructs and reports the potential energy landscape governing screw dislocation motion in high-entropy alloys (HEAs). It reveals a hierarchical and multilevel structure, which retards dislocation movement and can be regulated by introducing chemical short-range order.
High-entropy alloys (HEAs) with concentrated solid solutions are conceived to possess a rugged atomic and energy landscape in which dislocation motion necessarily proceeds to accommodate mechanical deformation. Fundamental questions remain as to how rough the energy landscape is and to what extent it can be influenced by the local ordering of their constituent elements. Here, we construct and report the potential energy landscape (PEL) governing screw dislocation motion in refractory HEAs that reveals a hierarchical and multilevel structure with a collection of small basins nested in large metabasin. This striking feature pertaining to HEAs exerts a trapping force and back stress on saddle point activations, retarding dislocation movement. By introducing chemical short-range order, the energy landscape is smoothed but skewed to different degrees that shifts the rate-liming process from kink-glide to kink-pair nucleation. The chemical disorder-roughened PEL in HEAs, analogous to structural disorder induced in metallic glasses, signifies the role of various barrier-hopping processes underlying the extraordinary mechanical behaviors of the two distinct groups of materials.(c) 2022 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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