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探讨了Ａｌ２Ｏ３、ＳｉＣ、ＳｉＯ２等三种颗粒增强Ａｌ－４％Ｍｇ复合材料凝固组织中显微孔隙的形成规律．结果表明：前者显微孔隙是由Ａｌ２Ｏ３颗粒加入导致熔体粘度增加、颗粒堵塞枝晶间的补缩流动通道以及颗粒与基体合金的热膨胀系数的差异三种因素所引起；第二种材料由于气孔易在ＳｉＣ颗粒表面形核，或者ＳｉＣ颗粒与基体结合较弱，使得该复合材料比前者易形成显微孔隙；第三种复合材料，是由于ＳｉＯ２颗粒与基体间发生了界面反应，一定量的Ｓｉ溶入了基体，增大了基体的凝固潜热，从而提高了基体合金凝固时的补缩流动能力，所以ＳｉＯ２ｐ／Ａｌ－４％Ｍｇ复合材料的凝固组织比同样条件下Ａｌ２Ｏ３ｐ／Ａｌ－４％Ｍｇ和ＳｉＣｐ／Ａｌ－４％Ｍｇ复合材料致密。
The formation of micropores in the solidified microstructure of Al-4% Mg composite reinforced with three kinds of Al2O3, SiC and SiO2 was investigated. The results show that the former is caused by the addition of Al2O3 particles, which leads to the increase of the viscosity of the melt, the shrinkage flow channel between the particles intercepting the dendrite, and the difference of thermal expansion coefficient between the particles and the matrix alloy. Easy to nucleate on the surface of SiC particles, or SiC particles and matrix bonding is weak, making the composite material easier to form micropores than the former; The third composite material is due to SiO2 particles and the substrate interface occurred, a certain amount of Si dissolves into the matrix and increases the latent heat of solidification of the matrix, thereby improving the shrinkage and flowability of the matrix alloy during solidification. Therefore, the solidification structure of the SiO2p / Al-4% Mg composite is lower than that of the Al2O3p / Al-4% Mg and SiCp / Al-4% Mg composites are dense.