Achieving enhanced mechanical, pseudoelastic and elastocaloric properties in Ni-Mn-Ga alloys via Dy micro-alloying and isothermal mechanical cyclic training

Abstract

In the present study, the combination of Dy micro-alloying and isothermal mechanical cyclic training (IMCT) was utilized to enhance the mechanical, pseudoelastic and elastocaloric properties of Ni-Mn-Ga shape memory alloys. The formation of granular DyNi4Ga precipitates contributed to remarkable improvement in both strength and ductility. The IMCT treatment produced a strong <001>NM preferred orientation through variant-selection and created internal stress, and thus resulted in significant increment in transformation strains and adiabatic temperature changes. Specifically, a giant adiabatic temperature change of -12.5 °C was achieved in the trained alloys, which was the highest value reported so far in Ni-Mn-Ga based shape memory alloys.