High-temperature superelasticity and competing microstructural mechanisms in Co₄₉Ni₂₁Ga₃₀ shape memory alloy single crystals under tension

A large temperature range of stress-induced martensitic transformation with >8% superelastic strain is demonstrated in [1 0 0]-oriented Co₄₉Ni₂₁Ga₃₀ single crystals. The nature of the superelastic response is greatly affected by temperature and test history due to the temperature-dependent dominant microstructural mechanisms. We provide an insight into these mechanisms and divide the response into three temperature stages. Interestingly, a small stress hysteresis of only 2 MPa was achieved after the superelastic experiments at 300 °C compared to 20 MPa of the virgin sample.