Study of fatigue behavior of Ti-Ni-Cu5% wires for different heat treatments

Abstract
Changes of memory properties and fatigue life of the Shape Memory Alloys (SMA) are very important for practical applications. In this work, several heat treatments have been done on a Ti-Ni-Cu5% wire. The thermomechanical properties during the fatigue life have been analyzed at several stress levels for each heat treatment. Ti-Ni-Cu wires were loaded by a static uniaxial tensile stress and submitted to thermal cycling. The wires were cycled until failure in an oil bath, cooled by this one and heated by electrical current. One modified Wöhier curve bas been obtained, the influence of the heat treatment temperature, applied stress and cycle number are analyzed. Finally, this work allows to select a heat treatment as a function of the application.