Fatigue behavior of Ti-Ni-Cu thin wires SME

Practical applications of the Shape Memory Effect (SME) involves frequently repetitive operations. Therefore, it's essential to have knowledge of the properties behavior related to SME under working conditions. The thermomechanical fatigue of Ti-Ni-Cu thin wires loaded by static uniaxial tensile stress and submitted to thermal cycling has been studied. The test samples were cycled until failure in oil bath, cooled by this one and healed by electrical current. One modified Wohler curve has been plotted and the influences of the applied stress and of the number of thermal cycles on the shape memory properties has been analyzed. It is shown that the martensitic transformation associated to SME changes according to stress level and/or number of thermal cycles. The degradation until failure of the Stress Assisted Two-way Memory Effect (SATWME) was set between 0 and 20% compared to initial value.