Compressive stress-induced martensitic transformation and elastocaloric effect in Cu-Al-Mn single-crystal alloy

In this study, the strain distribution and elastocaloric effect during compression of a superelastic [116]-oriented single-crystal Cu-Al-Mn shape memory alloy were investigated. Its superelastic behavior exhibited low critical stress (213 MPa), narrow stress hysteresis (111 MPa), and excellent superelasticity (near 9%). The detailed evolution of strain field during the superelastic cycle was analyzed by digital image correlation method. Multiple variants were triggered during its superelastic deformation, and uneven strain distribution was observed in the strain field. The temperature and strain fields of the four side surfaces showed inhomogeneous transformation in the single-crystal alloy. The elastocaloric temperature drops ranged from 3.1 K to 12.3 K when the sample was unloaded from prestrains of 2 %-9 %. The calculated theoretical elastocaloric effect was compared with the measured temperature drop, and the differences were confirmed to be related to non-uniform and incomplete martensitic transformation. This study presents a comprehensive analysis of the inhomogeneous transformation behavior and elastocaloric effect in [116]-oriented Cu-Al-Mn single-crystal alloy.

Automated summary

This study investigates the strain distribution and elastocaloric effect of a superelastic Cu-Al-Mn shape memory alloy during compression. The alloy exhibits low critical stress, narrow stress hysteresis, and excellent superelasticity. The strain field analysis reveals the presence of multiple variants and uneven strain distribution. The inhomogeneous transformation and differences between measured and theoretical elastocaloric effects are attributed to non-uniform and incomplete martensitic transformation.