Microstructure and mechanical properties of Ti₂Ni alloy fabricated by direct energy deposition

It is difficult to prepare Ti₂Ni alloys using traditional single-wire arc additive manufacturing. In this study, a Ti₂Ni alloy wall was fabricated in situ by double-wire arc additive manufacturing with pure Ti and Ni wires, and the resulting material has the potential to be applied to spacecraft and ground armor protection. In the stable region, the Ti: Ni content ratio was close to 2:1 after stabilization, indicating that the as-built wall was very close to the designed composition (Ti₂Ni). From the top of the wall to the substrate, the microstructure evolved as follows: Ti₂Ni + NiTi → Ti₂Ni + NiTi + α-Ti → α-Ti + Ti₂Ni. In the stable region, the hardness remained stable at approximately 660 HV_0.5.