Mechanical behavior of cycled shape memory alloy

Shape memory alloys (SMA) are often used in many industrial, medical and automotive fields due to the ability to recover the initial shape caused by external loads. This aspect is due to the variations of the microstructure that may depend on thermal and/or mechanical causes. So far, many models have been developed in order to describe the mechanical behaviour of SMA but most of them do not take into account the real microstructure. In this work a conventional equiatomic NiTi SMA has been investigated in both terms of microstructure evaluation and mechanical cycling behaviour up to degradation the memory ability, which has obtained at around 100 cycles. The cycling behaviour has been investigated and a model has been proposed to predict the mechanical behaviour and the ability to recover the initial microstructure. The damaged alloy has been investigated in terms of fracture surface analysis obtained by conventional tensile tests after 1, 50 and 100 cycles.