  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.
