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通过施加压应力的方法,在铁磁形状记忆合金Mn_2NiGa中引入残留内应力,研究了内应力对Mn_2NiGa材料的结构、相变和磁性能的影响.研究发现,加压过程使材料发生了塑性形变,在材料内部引入了大量的位错缺陷.卸载后保留的位错缺陷在材料中造成了残留的内应力,导致了马氏体相变温度大幅度提高,使原本室温下的母相转变成了马氏体相.测量到导致样品转变成马氏体的阈值压应力为1.0GPa.加压形成的马氏体中的残留内应力将矫顽力从低于50 Oe提高到350 Oe.残留内应力在730 K的热处理中由于位错缺陷的消失而得以消除,样品实现了马氏体逆相变.如此高的逆相变温度使得Mn_2NiGa马氏体的居里温度测量成为可能,获得了530K的数值.
Through the application of compressive stress, the residual internal stress was introduced into ferromagnetic shape memory alloy Mn_2NiGa to study the effect of internal stress on the structure, phase transition and magnetic properties of Mn_2NiGa materials.It was found that the material underwent plastic deformation , A large number of dislocation defects were introduced into the material.The dislocation defects remained after unloading caused the residual internal stress in the material, resulting in the significant increase of the martensitic transformation temperature and the transformation of the original phase at room temperature into The martensitic phase was measured and the threshold compressive stress resulting in the transformation of the sample into martensite was measured at 1.0 GPa.The residual internal stress in the compacted martensite increased the coercivity from less than 50 Oe to 350 Oe. The internal stress was eliminated due to the disappearance of dislocation defects in the heat treatment at 730 K. The sample achieved the reverse martensitic transformation.The high reverse transformation temperature made it possible to measure the Curie temperature of Mn_2NiGa martensite, 530K value.