Elastocaloric effect with small hysteresis in bamboo-grained Cu–Al–Mn microwires

Abstract

The elastocaloric effect in Cu–Al–Mn shape memory alloy microwires fabricated by Taylor–Ulitovsky method was investigated. The microwires with bamboo-like grain architecture, homogeneous composition and favorable orientation were successfully prepared through high-temperature annealing heat treatment. The formation of the bamboo grains and high specific surface area contribute to the reduced martensite transformation hysteresis. A large recoverable strain up to 8.8% was achieved by two-way shape memory cycling under a low stress of 50 MPa. Consequently, the microwire exhibited a large entropy change ΔSiso = 16.1 J kg−1 K−1. Furthermore, the refrigeration capacity (RC) reached ~ 502 J kg−1 over a working temperature interval ΔTFWHM = 31 K during direct transformation under 50 MPa uniaxial stress. Finally, a reversible adiabatic temperature change ΔTad = 3.9 K under a stress of 150 MPa was obtained. This proves that the present Cu–Al–Mn microwire, with bamboo grains, high refrigeration property and low cost, may act as promising candidate materials for elastocaloric cooling.