Si掺杂的铁磁形状记忆合金Co_(50)Ni_(21)Ga_(29)Si_x的物性研究

Characteristics of the Si-doped ferromagnetic shape memory alloy Co_(50)Ni_(21)Ga_(29)Si_x

成功生长了Co50Ni21Ga29:Si(x=1,2)单晶样品,对其磁性,马氏体相变及其相关性质进行了细致的测量.发现掺Si成分的单晶具有非常迅速的马氏体相变行为、2.5%的大相变应变、大于100ppm的磁感生应变和4.5%的相变电阻.进一步研究指出,在CoNiGa合金中掺入适量Si元素,能够降低材料的马氏体相变温度,减小相变热滞后,提高材料的居里温度,并使得磁性原子的磁矩有所降低.尤其重要的是Si元素的添加能够增大材料马氏体的磁晶各向异性能,改善马氏体变体的迁移特性,从而获得更大的磁感生应变.

In order to improve the properties of Co-Ni-Ga alloys, experiments of adding Si to Co50 Ni21Ga29 alloys were carried out to examine the effect of Si in quaternary Co50 Ni21 Ga29 Six （ x = 1-2 ） alloys on their structure, martensitic transformation behavior and magnetic properties. The Co50 Ni21 Ga29 Six （x = 1,2） single crystals were successfully grown. All the samples with low Si doping show a sharp martensitic transformation with increasing temperature. The single crystal samples show a completely recoverable two-way shape memory with a strain of 2.5 % upon the thermoelastic martensitic transformation. A large magnetic- field-induced strain of 1 10 ppm was measured at room temperature. A small quantity of Si doping can down-shift the martensitic transformation temperature, reduce the thermal hysteresis, decrease the magnetization but increase the Curie temperature. Especially, the Si doping can increase the magnetic anisotropy of Co-Ni-Ga-alloys, which is available to obtain large magnetic-field-induced strain in a low magnetic field. An electronic resistance ＂jump＂ of 4.5% upon the thermoelastic martensitic transformation was also reported.