Microstructure and mechanical properties of Ti-6Al-4V/Ni-Ti functionally graded material fabricated by multi-wire arc additive manufacturing

In this study, a Ti-6Al-4V/Ni-Ti functionally graded material was successfully prepared by multi-wire arc additive manufacturing. Its microstructural, electrochemical, and mechanical properties were studied. The results show that the microstructure is transformed from an α-Ti + β-Ti basket structure to an NiTi columnar crystal. With an increase in Ni content, I_corr decreases from 0.203 ± 0.017 μA/cm² to 0.145 ± 0.003 μA/cm², and E_corr increases from −409 ± 5 mV to −259 ± 3 mV. The microhardness increases from 335 ± 7 HV_0.2 to 615 ± 17 HV_0.2 in the gradient region and then decreases to 250 ± 8 HV_0.2. The ultimate compressive strength of the gradient region is 1253 ± 62 MPa.