Microstructure and properties of NiTi shape memory alloy fabricated by double-wire plasma arc additive manufacturing with a nearly equal atomic ratio

In this study, a Ni49Ti51 shape memory alloy was innovatively prepared using the double-wire arc additive manufacturing process with plasma arc as the heat source and pure Ni and Ti welding wires as the raw materials. The microstructure and properties were systematically studied. The results indicate that the microstructure of the prepared Ni49Ti51 shape memory alloy mainly consists of NiTi (B19 '), NiTi (B2), and NiTi2 phases. The ultimate compressive strength and fracture strain are 2241.3 MPa and 31.7 %, respectively. These values have increased by 39.7 % and 252.2 %, respectively, compared to the plasma arc powder melting process. Moreover, the shape memory effect is superior, exhibiting a shape memory recovery rate of up to 88 %.