On the Brittle-to-Ductile Transition of the As-Cast TiVNbTa Refractory High-Entropy Alloy

Abstract

The fracture properties of as-cast TiVNbTa, a refractory high-entropy alloy (RHEA), were investigated using four-point bending tests from -139°C to 20°C under a strain-rate of 10^-3 s^-1. From those tests and fractography, the conditional fracture toughness values and the brittle-to-ductile transition temperature were obtained. The brittle-to-ductile transition temperature was between -47°C to -27°C, which gives an estimated activation energy value of 0.52±0.09 eV for the alloy. This study provides a preliminary understanding of the nature of dislocation motion in a relatively ductile RHEA.

Keywords: High-Entropy Alloys, Refractory Metals, Fracture Toughness, Brittle-to-Ductile Transition, Bending Test, Refractory High-Entropy Alloys