低温时效处理对铁磁形状记忆合金Mn_2NiGa的结构、相变和磁性能的影响  

Low temperature aging effect on structure,martensitic transformation and magnetic properties in ferromagnetic shape memory alloy of Mn_2NiGa

作　　者：宋瑞宁[1,2] 李祥[2] 朱伟[1] 刘恩克[1] 李贵江[1] 蔡金芳[3] 王文洪[1] 吴光恒[1] 

机构地区：[1]中国科学院物理研究所磁学国家重点实验室,北京100190 [2]北京理工大学材料科学与工程学院,北京100081 [3]北京理工大学理学院,北京100081

出　　处：《物理学报》2011年第7期692-699,共8页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:50971130);国家重点基础研究发展计划资助(批准号:2010CB833102)资助的课题~~

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.在其浓度超过晶格的容忍度之后,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,样品又回到母相状态.观察到细小析出相粗化的两个阈值温度,分别为423K和485K.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.

关 键 词：铁磁形状记忆合金 Mn2NiGa 时效处理 内应力 

分 类 号：TG156.92[金属学及工艺—热处理]