(1. 齐齐哈尔大学 物理系，齐齐哈尔 161006； 2. 哈尔滨工业大学 材料科学与工程学院，哈尔滨 150001)
摘 要: 通过熔体抽拉法制备了直径为40~50 μm、长度为5~10 cm的多晶Ni50Mn25Ga25-xFex (x=1, 2, 3, 4, 5, 6, 摩尔分数，%)纤维，对制备态纤维采用步进式有序化后热处理，利用场发射扫描电子显微镜、透射电子显微镜、X射线衍射对其微观组织和成分进行表征，使用差示扫描量热分析仪和动态机械拉伸仪测试其相变行为和力学性能。结果表明：热处理后随着Fe掺杂的增加，纤维实现了从奥氏体相到马氏体相的转变，热处理态纤维具有不同的晶体类型，马氏体孪晶界更为平直、清晰，原子有序度明显提高。热处理可以提高相变温度，减小相变滞后，使马氏体相变更容易进行，提高了抗拉强度和断裂应变。综合分析阐明了Fe掺杂及有序化热处理影响微观结构、相变行为和力学性能的微观机制。
关键字: 形状记忆纤维；熔体抽拉；马氏体相变；有序化热处理；力学性能
（1. Department of Physics, Qiqihar University, Qiqihar 161006, China; 2. School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China）
Abstract:The polycrystalline Ni50Mn25Ga25-xFex (x=1, 2, 3, 4, 5, 6, mole fraction, %) microwires with diameter of 40- 50 μm and length of 5-10 cm were prepared by meld extraction technique. A step-wise chemical ordering annealing heat treatment was carried out. The microstructure and composition of microwires were characterized using field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometry (XRD). The phase transition behavior and mechanical properties were tested using differential scanning calorimetry (DSC) and dynamic mechanical analyzer (DMA). The results show that, after heat treatment along with the increase of the Fe doped, the microwires have realized from the austenite phase to the martensite phase transformation. The annealed microwires have different crystal types, the martensite exhibits straight clear twin boundary, and the atomic ordering increases. The annealing increases the transformation temperature and decreases the transformation hysteresis, and makes martensite transition easier. The annealing improves the tensile strength and breaking strain. Comprehensive analysis illustrates that the microcosmic mechanisms of Fe doping and ordering heat treatment affect the microstructure, phase transition behavior and mechanical properties.
Key words: shape memory microwires; melt extraction; martensite transformation; chemical ordering annealing; mechanical properties
