Characterization and Evaluation of Shape Memory Effect of Cu-Zn-Al Shape Memory Alloy

Abstract

For shape memory applications, Cu-based shape memory alloys have been presented as the “heir apparent” and more cost-effective alternative for NiTi alloys, which have traditionally been used. The variables that have been cited as causes for this forecast includes low material costs, simplicity of fabrication, and good shape memory effect. The essential feature of martensitic phase transitions is the athermal movement of atoms, with no input from diffusion. However, diffusive events may have large effects on relative phase stability, and therefore on transformation temperatures and functional characteristics. Cu-based shape- memory alloys exhibit these behaviours particularly well, with atomic diffusion occurring at room temperature in both the austenite and martensite metastable phases. Nevertheless, it seems that peer- reviewed literature on the same subject is insufficient for accurately quantifying the influence of Zn on Shape Memory Effect (SME) of Cu-Zn-Al Shape Memory Alloy(SMA). Hence in the current study synthesis of Cu-Zn- Al shape memory alloy through liquid metallurgical method using induction furnace and examining the microstructure and phase transformation which is related to SME. The study reveals that for the selected composition the shape memory effect varies from 42- 92% and with increase in Zn wt.% SME found to increase due to conversion of more austenite to martensite.