Homogenization of TiVTaNb refractory high-entropy alloy

Homogenization of refractory high entropy alloys (RHEAs) usually requires very high annealing temperatures and long periods due to the high melting temperature of alloying elements and the sluggish diffusion effects. TiVTaNb is a typical RHEA with excellent mechanical properties. The present work takes TiVTaNb as a model alloy and shows the influence of cold-deformation, annealing temperature, and annealing time on its homogenization microstructure. The optimal process parameters are determined as cold deformation of 80% thickness reduction, followed by annealing at 1250 °C for 48 h. The tensile deformation behavior of the homogenized alloy is then studied based on quasi-in situ tensile testing, showing a tensile strength of 766 MPa. The tensile deformation is accompanied by grain rotation, meanwhile, a large number of geometrically necessary dislocations piles-up at the grain boundaries.