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研究了快速凝固Ａｌ－２０Ｓｉ－１．３Ｃｕ－１Ｍｇ合金在４００℃热暴露不同时间Ｓｉ相在尺寸上的变化及其对挤压态合金室温、高温性能的影响．试验结果表明，Ｓｉ相尺寸对合金的室温性能有一定影响，经４０℃×１０２４小时暴露后，室温拉伸强度从挤压态的３３５ＭＰａ降到２２０ＭＰａ．热暴露后材料的高温（３００℃）拉伸强度开始急骤下降，但随后σｂ下降速度变缓，说明Ｓｉ相尺寸对材料高温拉伸性能的影响不是高温拉伸强度下降的主要因素．较大的Ｓｉ相颗粒是导致材料室温断裂的主要原因．
The change of size of Si phase in rapidly solidified Al-20Si-1.3Cu-1Mg alloy during thermal exposure at 400 ℃ and its effect on the properties of extruded alloy at room temperature and elevated temperature were studied. The results show that the Si phase size has some influence on the room temperature properties of the alloy. After 40 ℃ × 1024 hours exposure, the tensile strength at room temperature decreases from 335MPa to 220MPa. After heat exposure, the tensile strength of high temperature (300 ℃) began to drop sharply, but then the σb slowed down, which indicated that the influence of Si phase size on the high temperature tensile properties was not the main factor of high temperature tensile strength reduction. Larger Si phase particles are the main cause of room temperature rupture of the material.