Effect of Heat Treatment on Mechanical Behavior and Stabilization of Super-Elasticity of Nitinol Alloys Used in Smart Actuators

Abstract

In this work, the effects of heat treatment on the mechanical behavior and superelasticity stability of nitinol alloys used in smart actuators were studied. Heat treatment was carried out at different temperatures via solution treatment, aging at 300°C, 400°C, and 500°C. Aging at 400°C showed the optimum results to achieve a balance between strength and elasticity as a clear plateau appeared to express the behavior of superelasticity while the austenitic phase transformation temperature reached 16°C. This ensured the existence of the austenitic phase at room temperature, which is the fundamental criterion for medical and industrial applications. Also, the results showed reasonable enhancement in the fatigue life for the samples aged at 400°C and 500°C as the enhancement was three times the as-prepared sample. This confirms the significance of the fine control of heat treatment parameters to produce nitinol alloys for the targeted applications.