Pseudoelastic Deformation in Refractory (MoW) 85 Zr 7.5(TaTi) 7.5 High-Entropy Alloy
23 Pages Posted: 11 Mar 2021
Phase diagrams supported by density functional theory methods can be crucial for designing high-entropy alloys (HEAs). We present phase and property analysis of refractory quinary (MoW)xZry(TaTi)1-x-y HEAs from combined Calculation of Phase Diagram (CALPHAD) and density-functional theory results, supplemented by molecular dynamics (MD) simulations. Our analysis indicates a Mo-W-rich region of this quinary system has a stable single-phase body-centered-cubic (bcc). The (MoW)85Zr7.5(TaTi)7.5 was down-selected based on temperature-dependent CALPHAD phase diagram analysis and MD predicted elastic behavior that reveals twinning-assisted pseudoelastic behavior in this refractory HEA. While mostly unexplored in bcc crystals, twinning is a fundamental deformation mechanism that competes against dislocation slip in crystalline solids. This alloy shows identical cyclic deformation characteristics during uniaxial <100> loading, i.e., the pseudoelasticity is isotropic in loading direction. Additionally, a temperature increase from 77 to 1,500 K enhances the elastic strain recovery in load-unload cycles, offering possibly control to tune the pseudoelastic behavior.
Keywords: High-entropy alloy, Pseudoelasticity, DFT, CALPHAD, Molecular Dynamics
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