Irreversible strains in an Ni-Ti alloy after thermal cycling

摘要

Ni-Ti alloys with nearly equiatomic composition exhibit the shape memory effect based on a thermoelastic martensitic transformation. Because of the ability to recover substantial amounts of strain or to generate significant force upon changing shape these alloys can be used as materials for actuators in many applications. However, increasing permanent deformation after repeated phase trans-formations can restrict the applicability. Therefore, thermal cycling tests under constant load with an Ni-Ti alloy were carried out and the irreversible strain was measured as a function of the number of cycles and of the tensile stress.