LAUSR

Abstract Magnetic shape memory alloys have received much attention due to their intriguing physical and multifunctional properties, including magnetostrain, magnetoresistance, elastocaloric effect (eCE), and shape memory effect (SME). In order to develop improved materials, it is necessary to study the effect of microstructure on the material properties in greater depth. In this work, Mn50Ni32Sn7Co11 bulk alloys were obtained by copper mold suction casting, directional solidification, and quenching with different cooling rates. The effects of cooling rate on the microstructure and the corresponding eCE/SME were investigated. It was found that the content of γ phase (fcc structure) increased and martensitic transformation temperature decreased with decrease in the cooling rate. The solidification process of γ phase and the matrix phase was determined by studying the solid-liquid interface. Mn–Ni–Sn–Co alloys with γ phase exhibited ductile fracture behavior and better mechanical properties. The adiabatic temperature change was −2.6 K upon unloading. Moreover, shape memory behavior of as-quenched specimen was investigated by in situ digital image correlation technique in non-oriented polycrystalline materials. It was found that heterogeneous strain distribution reduced the SME. Therefore, this work provides a novel strategy for designing magnetic shape memory alloys with better ductility and multi-functional properties.