Transformation behaviors of Ti48.5Ni48Fe2Nb1.5 dependence of annealing and thermomechanical cycling

The effect of annealing treatments and thermomechanical cycling on the transformation behaviors and shape memory effect of Ti48.5Ni48Fe2Nb1.5 shape memory alloys were investigated using electrical resistivity measurement and tensile testing. It is found that the transformation behaviors are influenced considerably by the annealing treatments. Both M (s) and A (s) increase with increasing annealing temperature and cooling rate. Martensite stabilization occurs during thermomechanical cycles, thus resulting in lower M (s) and recovery ratio. Moreover, thermomechanical cycling leads to pseudo-elasticity. The yield point of stress-induced martensite (sigma (SIM)) increases with increasing cycles and pre-formation.