Ni-Mn-Ga-Fe铁磁纤维的马氏体相变和超弹性

通过熔体抽拉法制备直径在40~50μm、长度5~10cm的多晶Ni-Mn-Ga-Fe纤维,并进行步进式有序化热处理。利用场发射扫描电子显微镜、透射电子显微镜对其微结构进行了表征,利用差示扫描量热仪、磁学性质测量系统和动态机械拉伸仪测试了其相变行为和超弹性性能。结果表明,与制备态纤维相比,热处理后原子有序度显著提高,孪晶界更为平直、清晰,并获得了近完全超弹性,应变恢复率得到明显提高。第四元素Fe是调控马氏体相变温度的主要因素,磁场并未引起相变温度的移位,综合分析阐明了有序化热处理对微结构、超弹性的影响机制以及相变的影响因素。

Superelasticity and martensitic transformation of Ni-Mn-Ga-Fe ferro-magnetic fibers

In this paper, polycrystalline Ni-Mn-Ga-Fe fibers with diameter of 40 to 50μm and length of 5 to 10cm were prepared by meld extraction technique, and subsquently a step-wise chemical ordering annealing heat treatment was carried out. The microstructure of fibers was characterized using field emission scanning electron microscope (SEM) and transmission electron microscopy (TEM). The phase transition behavior and superelasticity properties were tested using differential scanning calorimetry (DSC), magnetic property measurement system (MPMS) and dynamic mechanical analyzer (DMA). The results show that after heat treatment, nearly completely superelasticity was observed and recovery ratio improved obviously due to the increase of ordering degree and martensite exhibited straight clear twin boundary. The fourth element Fe is the main factor tuning martensite transformation temperature and magnetic field did not cause a transformation temperature shift. Comprehensive analysis illustrates the influecing mechanism of ordering heat treatment affect the microstructure and superelasticity, and influence factors of transition behavior.