Colossal elastocaloric effect in a A oriented Ni49Mn33Ti18 polycrystalline alloy

Abstract

Solid-state elastocaloric cooling, exploiting the latent heat yielded by superelastic martensitic transformation, represents a very promising substitute for the conventional vapor-compression refrigeration technology. Seeking high-performance bulk elastocaloric materials is of great significance for the efficient energy conversion. Here, we demonstrate the extraordinary elastocaloric properties in a <001>A oriented Ni49Mn33Ti18 polycrystalline alloy prepared by directional solidification. The temperature change induced by compressive stress reaches an extremely high value up to −37.3 K and the stress-induced entropy change can be as large as 51.0 J kg−1 K−1. This colossal elastocaloric response originates from the giant transformation entropy change as well as the strong <001>A texture induced by directional solidification, allowing a reduction in the internal constraints from the differently oriented grains on the lattice deformation and thus a promotion on the release/absorption of latent heat due to enhanced volume fraction of transformed martensite induced by external stress.