Large Elastocaloric Effect in Fe‐Doped Co–Fe–V–Ga Shape Memory Alloys

Abstract

Herein, the impact of Fe substitution for Co on martensitic transformation (MT), crystal structure, elastocaloric effect (eCE), and mechanical characteristics in Co51V34Ga15 shape memory alloys (SMAs) is systematically investigated. The temperatures of MT are found to be properly adjusted by varying the Fe content in Co51−xFexV34Ga15 (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 Co50.7Fe0.3V34Ga15 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 Co50.7Fe0.3V34Ga15 alloy, which makes it the promising candidate for multifunctional materials.

Large Elastocaloric Effect Driven by Low Stress Induced in [001]-Oriented Polycrystalline Co51.6V31.4Ga17 Alloy

“…Meanwhile, the elastocaloric effect in textured polycrystalline alloys has less been studied systematically. A pronounced eCE has been found in Co-V-Ga alloys undergoing a stress-induced phase transformation from the L2 1 atomic ordered austenite to the DO 22 tetragonal martensite [29][30][31][32]. However, the reported eCE was observed in texture-free polycrystalline alloys.…”