Superelasticity preservation in dissimilar joint of NiTi shape memory alloy to biomedical PtIr

Laser microwelding was used to join, for the first time, superelastic NiTi to biomedical PtIr which can be used in multicomponent biomedical devices. By process optimization, it was possible to control the formation of the B2 NiTiPt phase, with no intermetallic compounds being formed. The NiTiPt phase inside the fusion zone had a strong metallurgical bonding with the NiTi base material due to the smooth transition of its grain orientation towards 〈111〉 B2 NiTi. The major finding of the present work is the preservation of the NiTi superelastic response in the welded joint as evidenced by the load/unloading cycling up to 6% strain, significantly higher than typically required for biomedical applications.