Grain Structure Related Inhomogeneous Elastocaloric Effects in Cu-Al-Mn Shape Memory Microwires

An inhomogeneous elastocaloric effect (eCE) has been found and investigated in the present Cu-Al-Mn shape memory microwires by using combined technique of infrared thermography and electron backscatter diffraction. Upon unloading, a reversible temperature change of ~5 K has been detected within the 5 mm gauge length. Inhomogeneous temperature distribution can be directly observed on the surface of microwires through infrared thermography measurement. Different regions of the microwires, involving bi-crystalline, oligo-crystalline, single-crystalline and poly-crystalline grain architectures, display different eCE cyclic stability, which can be ascribed to the heterogeneous grain architectures, the discrepancy of grain orientation and the varied neighboring grain constraints.