Effect of Dy addition on the microstructure and martensitic transformation of a Ni-rich TiNi shape memory alloy

The effect of rare earth element Dy addition on the microstructure and martensitic transformation behavior of Ti49.3Ni50.7 shape memory alloy was investigated by optical microscope (OM), scanning electronic microscope (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The results show that the microstructure of TiNiDy ternary alloy consists of Ti2Ni phase, DyNi phase and the matrix. One-step martensitic transformation is observed in quenched TiNiDy ternary alloys, which is the same as that in quenched TiNi binary alloys. The martensitic transformation temperatures increase evidently with Dy addition, and the maximum increase of Ms is about 110 °C.