(1. 北京有色金屬研究總院 國家有色金屬及電子材料分析測試中心，北京100088；
2. 中國科學院 物理研究所 磁學國家重點實驗室，北京100190)
摘 要: 采用X射線衍射分析與透射電子顯微分析相結(jié)合的方法，對鐵磁形狀記憶合金Mn2+xNiGa(x=0, 0.02, 0.06)室溫下微觀組織結(jié)構(gòu)進行研究。XRD結(jié)果表明：3種合金在室溫下主要為奧氏體相。TEM以及HREM觀察發(fā)現(xiàn)Mn含量對合金母相的微觀組織形態(tài)有很大影響，在Mn2NiGa合金基體中存在Ni2In型六角結(jié)構(gòu)的MnNiGa相；除存在MnNiGa相外，Mn2.02NiGa合金基體中還出現(xiàn)了少量層狀無調(diào)制結(jié)構(gòu)馬氏體相；Mn2.06NiGa合金中不存在MnNiGa相，基體中有大量的無調(diào)制馬氏體。HREM觀察發(fā)現(xiàn)，3種合金在室溫下都存在局域的晶格畸變，這種晶格畸變形成納米尺度微疇，具有應變玻璃相的特征。
關(guān)鍵字: 鐵磁形狀記憶合金；Mn2NiGa；馬氏體相變；顯微組織
（1. National Center of Analysis and Testing for Nonferrous Metals and Electronic Materials,
General Research Institute for Nonferrous Metals, Beijing 100088, China;
2. State Key Laboratory for Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China）
Abstract:The microstructures of the ferromagnetic shape memory alloys Mn2+xNiGa (x=0, 0.02, 0.06) at room temperature were investigated by X-ray diffractometry and TEM. XRD results show that the main phases of all the three alloys are austenites. By TEM and HREM, remarkably various microstructures can be found in Mn2+xNiGa alloys with different contents of Mn element. Ni2In-type hexagonal MnNiGa phase is found in the Mn2NiGa alloy. Beside MnNiGa phase, a few of layered non-modulated martensites appear in matrix of Mn2.02NiGa alloy. Non-modulated martensites appear conspicuously in Mn2.06NiGa alloy, meanwhile, MnNiGa phase disappears in this alloy. By HREM observation, the local lattice distortions which form nano-scaled domains with a characteristic of strain glass are found in the austenites of these three alloys at room temperature.
Key words: ferromagnetic shape memory alloy; Mn2NiGa; martensitic transformation; microstructures
