中文摘要：

对在较低温度范围的时效处理铁磁形状记忆合金Mn2NiGa的结构、相变和磁性进行了研究．研究发现，母相基体析出了细小的析出相，引起了晶格扭曲和畸变，导致了系统内产生了很大的内应力．存其浓度超过品格的容忍度之后，提升了体系的马氏体相变温度，使母相在时效温度下转变成马氏体相，并在其中测量到高达900Oe的矫顽力．由于这种马氏体相的逆相变温度大幅提高，外推获得其居里温度在530K附近．细小析出相的粗化使内应力消失，样品义回到母相状态．观察到细小析出相粗化的两个阈值温度，分别为423K和485K．

英文摘要：

The structure, the martensitic transformation and the magnetic properties of ferromagnetic shape memory alloy Mn2NiGa aged at low temperature are investigated. The lattice distortion and the internal stress are generated in the samples due to the fine precipitation generated during the aging treatment. When the precipitation concentration exceeds the tolerance limit of the parent phase lattice, it causes the martensitic transformation temperature to increase obviously, and thus the parent phase transforms to martensitic phase with a large coercivity up to 900 Oe. Because of the existence of internal stress, the reverse martensitic transformation is shifted toward high temperature up to 485 K. By extrapolating the experimental data, the Curie temperature of martensite is estimated at 530 K. The internal stress disappears and the martensite turns to be of the parent phase due to the coarsening of the precipitation at higher temperature. Two coarsening threshold temperatures are found to be 423 K and 485 K which are the temperature sensitive and the aging time sensitive, respectively.