Influence des traitements thermomécaniques antérieurs sur le comportement en fatigue de fils en alliage à mémoire de forme Ti-45%Ni-5% Cu

Influence of previous thermo-mechanical treatments on the shape memory fatigue behaviour of ti-45%ni-5%Cu wires

¹ on leave from CONACYT, Mexico DF/UANL, San Nicolas de los Garza, N.L., Mexico
² GEMPPM-Bât. Blaise Pascal, UMR CNRS 5510, INSA de Lyon, 20 Avenue Albert Einstein, F-69621 Villeurbanne, France

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 after 30% cold drawing. The memory properties during the fatigue life have been analyzed at several stress levels for each previous 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. A modified Wohler curve has been obtained, the influence of the heat treatment temperature, applied stress and cycle number are analyzed. Finally, this work allows to select the best suitable heat treatment for a given application.