Effect of Alloying on Intrinsic Ductility in WTaCrV High Entropy Alloys

Abstract

Tungsten (W) is a material known to possess favorable attributes for extreme applications, such as the divertor in magnetic fusionreactors, but its viability is limited due to poor manufacturability and insufficient irradiation resistance. In this work, we studythe intrinsic ductility of body-centered cubic WTaCrV high entropy alloys (HEAs). The ductility evaluations are carried out using a criterion based on the competition between the critical stressintensity factors for emission (KIe) and cleavage (KIc) in the {110} slip planes and {110} crack planes, which are evaluated withinthe linear elastic fracture mechanics framework and computed using density functional theory. The results suggest thatincreasing the alloying concentrations of V and reducing the concentrations of W can significantly improve the ductility in theseHEAs. The elastic anisotropy for these HEAs is analyzed using the Zener anisotropy ratio and its correlation with the concentrationof W in the alloys is studied. Results indicate that these alloys tend to be fairly isotropic. The computed data for the elastic constants is validated against available experimentaldata. Multiplephenomenological ductility metrics were also computed and analyzed against the analytical model. The results suggest that thesemodels have a much higher computational efficiency due to less number of parameters required for their computation using DFT.Some models, like the surrogate D parameter and the Pugh ratio, show a good correlation with the Rice model. The potential ofthese empirical models to serve as surrogate screening models for optimizing the compositional space is also discussed.

Keywords: High entropy alloys (HEAs), Mechanical Response, Tungsten, Ductility, BCC refractory metals, Anisotropy