Microstructural evolution and mechanical properties of the heterogeneous structure of Ti-6Al-4V/Ni-Ti with pure Cu as an intermediate layer

In this study, the heterogeneous structure of Ti-6Al-4V/Ni-Ti was fabricated in situ using multiwire arc additive manufacturing (M−WAAM) technology by adding pure Cu as an intermediate layer between Ti-6Al-4V and Ni-Ti alloys. The results indicate that the transition layer of the as-built component primarily consists of the Ti(Ni, Cu), Ti 2 (Ni, Cu), and (Ni, Cu) 2 Ti phases. Additionally, the interface between Ti-6Al-4V and the Cu interlayer exhibits irregularly sized, interwoven acicular precipitates, identified as the Ti 2 (Ni, Cu) phase. Above this region, the Ti 2 (Ni, Cu) precipitates and Ti(Ni, Cu) matrix maintain the crystallographic orientation relationship: (313) Ti2(Ni, Cu) // (011) Ti(Ni, Cu) and [5_6_]3 Ti2(Ni, Cu) // [02_2] Ti(Ni, Cu) . The hardness at the interface increases to 512.6 HV 0 . 2 . Besides, this heterostructure exhibited an average ultimate tensile strength of 270 MPa and an elongation of 6.5%.