Ab-initio study of the structural, elastic and dislocation properties of body-centered cubic refractory HfNbTaTiZr high entropy alloy

TL;DR

This paper investigates the dislocation core structures in bcc HfNbTaTiZr high entropy alloys, revealing variability linked to chemical short-range order and discussing implications for plasticity and mechanical properties.

Contribution

It provides the first ab-initio analysis of dislocation core structures in this complex high entropy alloy, highlighting the influence of short-range order on dislocation behavior.

Findings

Dislocation cores vary between compact, split, and degenerate forms.

Chemical short-range order affects dislocation core structures.

Implications for tailoring mechanical properties through microstructural control.

Abstract

This study delves into bcc HfNbTaTiZr refractory high entropy alloys, focusing on the $\frac{1}{2}\langle111\rangle$ screw dislocation core structures. While traditional observations in pure elements often revealed compact dislocation cores, our investigation reveals variability, including instances of compact, split, or degenerate cores. Building upon the current understanding of dislocation behavior, we propose that this observed variability may be intricately linked to the presence of chemical short-range order within the alloy. The unique composition of HfNbTaTiZr, between bcc and hcp elements, introduces a dynamic interplay influencing the dislocation core structure. In light of these findings, we discuss the implications for plasticity mechanisms in high entropy alloys. The presence of varied dislocation core structures suggests a complex interplay between local phases and short-range ordering, influencing the material's response to external stresses. This challenges the conventional understanding of dislocation-mediated plasticity and opens avenues for tailoring the mechanical properties of refractory alloys through the controlled manipulation of short-range order.