Electron beam weldability of TiZrNbTa refractory high-entropy alloy and TC4 titanium alloy

Abstract

Welding is a crucial process for the application of new materials in engineering. By welding refractory high-entropy alloys with other alloys, a composite structure can be formed that not only combines the advantages of both materials but also reduces costs. This paper focuses on evaluating the electron beam weldability of TiZrNbTa refractory high-entropy alloy. Additionally, it presents an innovative approach to achieve dissimilar electron beam welding of TiZrNbTa and TC4 titanium alloy, resulting in defect-free welded joints. The microstructure of the two groups of welds was analyzed, and the relationship between microstructure evolution and the mechanical properties of the joint was studied. The microstructure characterization of the two sets of welds was carried out after welding, and the relationship between the weld tissue evolution and the mechanical properties of the joints was investigated. It was found that the grains in the fusion zone of TiZrNbTa were significantly refined and the casting holes were significantly reduced. Although macroscopic segregation was found in the dissimilar welds, the subsequent tensile tests revealed a 10% increase in tensile strength over TiZrNbTa at 389 MPa. In addition, the dissimilar joints exhibited excellent compression strength and compressive yield strain (1280 MPa, 23.5%). However, both had poor tensile plasticity, a typical brittle fracture mode, and the fracture occurred on the TiZrNbTa parent material side, and the reason for the fracture was explained. This study confirms for the first time the good weldability of TiZrNbTa and TC4 titanium alloy, which provides theoretical support for the engineering application of refractory high-entropy alloys.