Microstructure and mechanical properties of a functionally graded material from TA1 to Inconel 625 fabricated by dual wire + arc additive manufacturing

Abstract Functionally graded material (FGM) from Ti to Ni alloy has potential applications in extreme environment condition such as aerospace or nuclear reactor area. However, the manufacturing of the FGM is not easy using traditional methods. In this study, the dual wire + arc additive manufacturing technology with TA1 and Inconel 625 wires was used to fabricate a FGM from TA1 to Inconel 625. The microstructure and mechanical characteristics of the FGM parts were investigated. The results showed that the FGM microstructure was changed from bottom to top: α-Ti + β-Ti + NiTi2 → β-Ti + NiTi2 + NiTi → NiTi + Ni3Ti + (Cr, Mo) → γ-Ni + NiTi + Ni3Ti + Laves + (Cr, Mo). The microhardness of FGM ranged from 171 HV0.2 to 852.56 HV0.2. The average ultimate compressive strength of the vertical samples was 1762.18 MPa. The compression fracture of the sample was brittle fracture.