Enhanced cyclic stability and enlarged working temperature window of NiFeGa elastocaloric refrigerant via introducing strong texture and ductile interfacial precipitate

Abstract

The poor mechanical properties will result in low fatigue life and limited working temperature window of elastocaloric effect (eCE) for ferromagnetic shape memory alloys with lower critical stress. In this work, a microstructure design strategy, i.e., simultaneously introducing strong texture and ductile interfacial γ-phase, was adopted to reduce the strain discontinuity near the grain boundary and enhance the grain boundary cohesion, further improving the mechanical properties and eCE performance. With this strategy, the compressive strength and strain of the prototype Ni54Fe19Ga27 alloy can exceed 1.5 GPa and 30.0% at room temperature, respectively. Furthermore, a wide working temperature window of 120 K with an adiabatic temperature change of −8.5 to −1.2 K and superior eCE fatigue life of 2 × 104 cycles with an adiabatic temperature change of ∼3 K have been achieved. This work is expected to provide an effective strategy to enhance the eCE performance of ferromagnetic shape memory alloys.