(中南大學(xué) 材料科學(xué)與工程學(xué)院, 長沙 410083)
摘 要: 采用光學(xué)顯微鏡、 掃描電鏡、 能譜分析、 透射電鏡和X射線衍射分析等研究了7A55合金鑄態(tài)與均勻化顯微組織演化與成分分布，確定了該合金的均勻化處理溫度與過燒溫度， 研究了鑄錠均勻化動力學(xué)過程， 利用菲克定理導(dǎo)出了均勻化動力學(xué)方程， 利用動力學(xué)方程對均勻化過程中合金元素的擴(kuò)散、 Al3Zr的析出、 難熔相的聚集和球化現(xiàn)象進(jìn)行了解釋。 根據(jù)實驗及計算結(jié)果， 得出合理均勻化處理工藝為470 ℃均勻化24 h。
關(guān)鍵字: 7A55合金; 均勻化動力學(xué); 枝晶間距
（ 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
