Microstructure and mechanical properties of electron beam welded TiZrNbTa refractory high entropy alloy

It is stringent to develop welding techniques for refractory high entropy alloys (RHEAs) to fabricate large-sized components, since it is difficult to fabricate large-sized RHEA castings because of their poor fluidity and severe element segregation. Here, we first time utilize electron beam welding (EBW) to join TiZrNbTa RHEA, and a defect-free joint is successfully achieved. After EBW, a coarse casting microstructure is largely refined with the reduction of casting porosities. The average hardness in the entire joint is almost uniform, which is the comprehensive effect between the weakening of solution strengthening and the grain refinement strengthening. The tensile strength of the joint achieves 940 MPa, with a high strength efficiency of 90%. This study provides a way to fabricate large-sized RHEA components.