Reducing mechanical hysteresis via tuning the microstructural orientations in Heusler-type Ni44.8Mn36.9In13.3Co5.0 elastocaloric alloys

Abstract

Material coefficient of performance (COPmat), which is defined as the ratio of the latent heat extracted from a caloric material to the input work required, is fundamentally important in the material level for solid-sate cooling. For elastocaloric cooling, mechanical hysteresis affects the magnitude of hysteresis energy loss (reflecting the input work) in one mechanical cycle and even the fraction of reversible transformation phase (related to the output heat) during the successive mechanical cycles. Here, we achieved a narrow isothermal stress hysteresis (34 MPa) under a large compressive strain (6%) in a Ni–Mn–In–Co bulk polycrystalline alloy, by tuning the crystal orientation feature. Such a narrow-hysteresis alloy show dominant crystal orientations of [100]A and [331]A. Moreover，a variation in the COPmat can even vary by almost a factor of 2.6, due to the variation in the preferred orientation constitute. This optimization strategy, which enhances the COPmater by controlling the crystal orientations, provides a new clue in designing energy-efficient elastocaloric alloy systems with large elastic anisotropy.