Huge high-temperature superelasticity and complete strains recovery above 773 K in Ni–Mn–Ga-based microwire

There is an urgent need to develop high-performance high-temperature shape memory alloys (HTSMAs) that can be used as smart components in the fast-developing aerospace, robotics, manufacturing, electricity plant, and energy exploration industries. Here, a high-performance (Ni55.5Mn23.5Ga21)99.65B0.3Ce0.05 HTSMA microwire has been developed. Owing to the oligocrystalline structure and favorable orientation, the microwire shows huge superelasticity from 623 to 783 K, with a maximum recoverable strain up to 16.2% and recoverable strains above 14.0% in the whole temperature range. Meanwhile, the irrecoverable strains of the microwire were less than 0.24% during unloading in the temperature range from 673 to 783 K. These properties are in sharp contrast to the typical HTSMAs that display rapid increase in the irrecoverable strains and fast degradation of the recoverable strains above 673 K. Noticeably, all the irrecoverable strains reduced to zero, and complete strains recovery were achieved, after heating to higher temperature. Combined with the advantages of high-temperature superelasticity and complete strains recovery above 773 K, small size, low cost, and easy fabrication, the microwire shows a great potential in small-scale high-temperature intelligent devices.