On the Brittle-to-Ductile Transition of the As-cast TiVNbTa Refractory High-entropy Alloy

TL;DR

This study investigates the fracture behavior and brittle-to-ductile transition of the as-cast TiVNbTa refractory high-entropy alloy across a range of temperatures, revealing key transition temperatures and fracture toughness characteristics.

Contribution

It provides the first detailed analysis of the brittle-to-ductile transition and fracture toughness of TiVNbTa RHEA, highlighting its dislocation behavior and transition temperature range.

Findings

Brittle-to-ductile transition occurs between -47°C and -27°C.

Estimated activation energy for transition is 0.52 eV.

Fracture toughness and transition temperature are characterized.

Abstract

The fracture properties of as-cast TiVNbTa, a refractory high-entropy alloy (RHEA), were investigated using four-point bending tests from -139C to 20C 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 -47C to -27C, 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.