Ultra-wide-temperature-range superelasticity and intrinsic two-way shape memory effect in Co–Ni–Ga microwires

Abstract

We demonstrate perfect superelasticity and inherent two-way shape memory effect in Co49Ni21Ga30 microwires fabricated by a Taylor–Ulitovsky method. With the formation of an almost complete [001]A-oriented single crystal along the axis of the wire, the as-drawn microwire displays great superelastic behaviors with a large reversible tensile strain of >8% over an ultra-wide temperature window of 550 K (223–773 K). Simultaneously, an excellent intrinsic two-way shape memory effect with a considerably large strain output (∼6.3%) was also obtained in this Co49Ni21Ga30 microwire. After mechanical training, the two-way shape memory strain can reach up to 6.8% at a low operating temperature. With the combination of above extraordinary functional properties and the low cost of fabrication, the Co49Ni21Ga30 microwire holds a significant potential for applications in miniature sensing and self-actuating devices in the future.