Abstract:
Hexagonal MnMX-based (M = Co or Ni, X = Si or Ge) alloys exhibit giant reversible barocaloric effects. However, giant volume expansion would result in the as-cast MnMX ingots fragmenting into powders, and inevitably bring the deterioration of mechanical properties and formability. Grain fragmentation can bring degradation of structural transformation entropy change during cyclic application and removal of pressure. In this paper, giant reversible barocaloric effects with high thermal cycle stability can be achieved in the epoxy bonded (MnCoGe)
0.96(CuCoSn)
0.04 composite. Giant reversible isothermal entropy change of 43.0 J∙kg
−1∙K
−1 and adiabatic temperature change from barocaloric effects (∆
TBCE) of 15.6 K can be obtained within a wide temperature span of 30 K at 360 MPa, which is mainly attributed to the integration of the change in the transition temperature driven by pressure of −101 K∙GPa
−1 and suitable thermal hysteresis of 11.1 K. Further, the variation of reversible ∆
TBCE against the applied hydrostatic pressure reaches up to 43 K∙GPa
−1, which is at the highest level among the other reported giant barocaloric compounds. More importantly, after 60 thermal cycles, the composite does not break and the calorimetric curves coincide well, demonstrating good thermal cycle stability.