| 摘 要： | Ni_(50)Mn_(25)Ga_(20)Fe_5 ferromagnetic shape memory alloy microwires with diameters of ～ 30–50 μm and grain sizes of ～ 2–5 μm were prepared by melt-extraction technique. A step-wise chemical ordering annealing was carried out to improve the superelasticity strain and recovery ratio which were hampered by the internal stress, compositional inhomogeneity,and high-density defects in the as-extracted Ni_(50)Mn_(25)Ga_(20)Fe_5 microwires. The annealed microwires exhibited enhanced atomic ordering degree, narrow thermal hysteresis, and high saturation magnetization under a low magnetic field. As a result, the annealed microwire showed decreased superelastic critical stress, improved reversibility, and a high superelastic strain(1.9%) with a large recovery ratio(96%). This kind of filamentous material with superior superelastic effects may be promising materials for minor-devices.
|
