Giant elastocaloric effect and its irreversibility in [001]-oriented Ni45Mn36.5In13.5Co5 meta-magnetic shape memory alloys

In this letter, we investigate the elastocaloric reversibility in Ni-Mn-In-Co meta-magnetic shape memory alloys. A highly [001] textured Ni45Mn36.5In13.5Co5 polycrystalline alloy was grown by using the liquid-metal-cooling directional solidification technique. We have observed a giant adiabatic temperature change (ΔT) of +8.6 K caused by the stress-driven complete martensitic transformation. The asymmetry of the maximum ΔT between loading and unloading strongly depends on the magnitude of superelastic strain. Such an irreversible behavior is ascribed to the friction energy dissipation as well as the variation of the elastocaloric entropy change by shifting initial temperatures.