Enhanced elastocaloric effect and cycle stability in B and Cu co-doping Ni-Mn-In polycrystals

A Ni-Mn-In Heusler alloy is a typical system with large elastocaloric and magnetocaloric effects due to the coupling of structural transformation and magnetic transition, which provides a way to improve the refrigerant performance by coupling the external mechanical stress and magnetic field. Here, we investigate the phase constitution, martensitic transformation behavior, mechanical properties, and elastocaloric effect in (Ni52Mn31In17-xCux)B0.2 (x = 0, 1, 2, 3)alloys. It is found that the (Ni52Mn31In16Cu1)B0.2 polycrystal exhibits a giant adiabatic cooling of −9.5 K at a low stress of 220 MPa which has a large value of |ΔTad unloading|/σ about 43.2 K/GPa. This is a remarkable |ΔTad unloading|/σ obtained among all the reported Ni-Mn-In Heusler alloys. It also maintains a good functional stability with the ΔTad unloading of −6.8 K after 100 cycles at a high strain of 3%, indicating that it is a promising candidate for an elastocaloric refrigeration material with excellent comprehensive properties.