Structure-property correlation study on biocompatibility of wire arc additively manufactured nitinol alloy

Wire arc additive manufacturing (WAAM) provides a cost-effective approach for fabricating NiTi alloys for biomedical applications. In this study, a NiTi alloy wall was fabricated using WAAM and systematically evaluated for its microstructure, mechanical properties, corrosion resistance, and biocompatibility. EBSD analysis showed mainly high-angle grain boundaries, while XRD confirmed the dominant B2 austenitic phase with minor B19' martensite. Microhardness increased from 282 to 380 HV with increasing build height, while tensile strength ranged from 550 to 615 MPa. XPS analysis revealed a TiO₂-rich passive surface layer, which enhanced wettability, as indicated by contact angles of 29.93° and 25.95°. Electrochemical testing measured a corrosion rate of 0.013 mm year^-1. Hemolysis was below 1%, and MG-63 cell viability reached 91.18%. These results show that WAAM-fabricated NiTi exhibits favorable structural integrity and biocompatibility, making it suitable for potential orthopedic implant applications.