(中南大学 材料科学与工程学院, 长沙 410083)
摘 要: 采用光学显微镜、 扫描电镜、 能谱分析、 透射电镜和X射线衍射分析等研究了7A55合金铸态与均匀化显微组织演化与成分分布，确定了该合金的均匀化处理温度与过烧温度， 研究了铸锭均匀化动力学过程， 利用菲克定理导出了均匀化动力学方程， 利用动力学方程对均匀化过程中合金元素的扩散、 Al3Zr的析出、 难熔相的聚集和球化现象进行了解释。 根据实验及计算结果， 得出合理均匀化处理工艺为470 ℃均匀化24 h。
关键字: 7A55合金; 均匀化动力学; 枝晶间距
（ School of Materials Science and Engineering,
Central South University, Changsha 410083, China）
Abstract: The microstructure evolution and composition distribution of the 7A55 cast and homogenized alloy were studied by optical microscopy, scanning electron microcopy， energy dispersive spectrometer, transmission electron microscopy and X-ray diffractometry. The homogenizing and overburnt temperatures of the alloy were determined. Meanwhile, the diffusion kinetics of the alloy elements during homogenizing treatment was investigated and the homogenizing kinetic equation was deduced according to Fick's First Law of diffusion. The diffusion of alloy elements, precipitation of Al3Zr particles and the conglomeration and globe of the insoluble phases were explained by the equation during homogenization. According to the results of experiment and calculation, the proper homogenizing process of 7A55 alloy is at 470 ℃ for 24 h.
Key words: 7A55 alloy; homogenizing dynamics; dendrite arm space
