The hierarchical energy landscape of edge dislocation glide in refractory high-entropy alloys

F Zhao and WB Liu and Y Zhang and HL Duan, JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS, 193, 105887 (2024).

DOI: 10.1016/j.jmps.2024.105887

Refractory high-entropy alloys (RHEAs) are considered as potential candidates for high- temperature applications, with the glide resistance of edge dislocations being a crucial factor in determining the high- temperature strength. However, the solid-solution strengthening mechanism of edge dislocations in RHEAs is not fully understood. The existing Labusch-type models mainly focus on the long-range interaction of solute atoms with the dislocation stress field, while there is little attention paid to the short-range interaction in the dislocation core region. Here, we conduct carefully designed atomic simulations to decouple the long-range and short-range interactions in a typical RHEA, NbMoTaW. Furthermore, the total change in solute-dislocation interaction energy is decomposed, and a hierarchical energy landscape is revealed, demonstrating that the short-range interaction at the core region gains more importance in the solid- solution strengthening of edge dislocations in NbMoTaW. Then, we determine the Larkin length, which signifies the transition from size-dependent to size-independent dislocation behavior. The activation barrier extracted from the simulation with the dislocation length above the Larkin length is incorporated into the crystal plasticity model, and the high-temperature yield strength is well predicted by the strengthening from edge dislocations. Our work provides deep insight into the solid-solution strengthening mechanism in random solution solids, elucidating the importance of the local atomic configuration around the dislocation core.

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