Large elastocaloric effect in Fe-doped Co-Fe-V-Ga shape memory alloys

Herein, the impact of Fe substitution for Co on martensitic transformation (MT), crystal structure, elastocaloric effect (eCE), and mechanical characteristics in Co${}_{51}$V${}_{34}$Ga${}_{15}$ shape memory alloys (SMAs) is systematically investigated. The temperatures of MT are found to be properly adjusted by varying the Fe content in Co${}_{51-x}$Fe${}_x$V${}_{34}$Ga${}_{15}$ (x = 0, 0.3, and 0.6) alloys, shifting toward the lower values as the Fe concentration increases. Furthermore, alloying with Fe is shown to significantly improve the eCE and superelastic properties of these alloys. Under the uniaxial stress of 600 MPa, the Co${}_{50.7}$Fe${}_{0.3}$V${}_{34}$Ga${}_{15}$ alloy exhibits a significant adiabatic temperature drop of -9.5 K under adiabatic cooling conditions. Moreover, it demonstrates good stability during the cycling test with a stable temperature change of -6.6 K remaining nearly constant after 420 cycles under 500 MPa. Additionally, a maximum compressive strength of approximately 1500 MPa is achieved in the Co${}_{50.7}$Fe${}_{0.3}$V${}_{34}$Ga${}_{15}$ alloy, which makes it the promising candidate for multifunctional materials. (© 2022 Wiley‐VCH GmbH)