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 10−3s−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.