Achieved good mechanical properties and large elastocaloric effect in Ni-Mn-Ti-Cu-B alloy: Experiments and first-principles calculations

Solid-state refrigeration relying on the caloric effects of materials during phase transformation has attracted extensive attention for its great potential to replace the conventional vapor-compression technique. Here, we have optimized the mechanical properties of the Ni-Mn-Ti alloys via Cu and B co-doping. The reasons for the enhanced mechanical properties were systematically studied by experiments and first-principles calculations. The (Ni50Mn30.75Ti18.25Cu1)99.8B0.2 directionally solidified alloy can reach maximum compressive strength and strain of 2860 MPa and 20.4% at room temperature, respectively. A large adiabatic temperature change of up to 29.2 K can be achieved during stress-induced martensitic transformation. Besides, the adiabatic temperature change between loading and unloading cycles at 4% strain can be maintained at ∼11.3 K and basically do not decline after 650 cycles, which indicates that the present alloy has good cyclability of elastocaloric effect. Simultaneously achieved large elastocaloric effect and good mechanical properties at room temperature, Ni-Mn-Ti-Cu-B alloy has a great prospect for solid-state refrigeration applications.