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采用粉末冶金工艺制备Ni_2FeSb三元形状记忆合金。利用膨胀实验研究合金的烧结动力学;采用XRD和SEM分别考察粉末样品和烧结样品的显微组织和形貌;测定烧结样品表面的显微硬度。结果表明:研磨时间对粉末样品的形状、晶粒尺寸和晶体结构的均匀性具有显著影响。经较长时间研磨的样品具有较高的相对密度和较均匀的元素分布,且为L21和马氏体相,这些性能使合金具有形状记忆功能。在温度为750~1273 K条件下,合金的激活能为109~283 kJ/mol,这表明烧结过程主要由体积扩散控制。增加研磨时间和加热速率,合金的显微硬度得到提高。
Preparation of Ni_2FeSb ternary shape memory alloy by powder metallurgy. The sintering kinetics of the alloy was studied by swelling experiment. The microstructure and morphology of the powder sample and the sintered sample were investigated by XRD and SEM. The microhardness of the sintered sample was measured. The results show that the grinding time has a significant effect on the shape, grain size and uniformity of the crystal structure of the powder samples. Samples that grinded for longer periods had higher relative density and a more uniform elemental distribution, with L21 and martensite phases, all of which gave the alloy a shape memory function. At 750 ~ 1273 K, the activation energy of the alloy is 109 ~ 283 kJ / mol, which indicates that the sintering process is mainly controlled by volume diffusion. Increasing the grinding time and heating rate, the microhardness of the alloy is improved.