【摘要】 研究了挤压铸造工艺参数和SiC泡沫增强体对ZL109铝合金基体凝固组织的影响,探讨了复合材料的凝固过程．结果表明,采用先浇注基体熔体、后放置骨架的复合工艺制备的复合材料组织比先放置骨架、后浇注熔体的复合材料均匀; SiC泡沫增强体降低了复合压力对基体组织的影响,使得提高复合压力虽然可以细化基体的组织,但效果不明显． SiC泡沫增强体对基体的晶粒尺寸没有明显的影响,但是改变了晶粒的形态．泡沫孔内的α-Al初晶表现为粗大的柱状晶,其方向垂直于泡沫增强体的筋．泡沫孔的尺寸越小,越容易形成枝晶组织,枝晶的方向性越强． SiC／ZL109铝合金双连续相复合材料基体凝固时, α-Al 首先在泡沫筋的附近形核,然后逐渐向泡沫孔的中心长大．α-Al枝晶形成轮廓以后,中心富硅区发生共晶反应,筋表面的共晶硅最后形成．更多还原

【Abstract】 The solidification process of SiC/Al alloy ZL109 co-continuous composites fabricated by squeeze casting method, and the effects of SiC foam and process parameters on solidification structure were investigated. The microstructure of composites fabricated by late pouring molten matrix is more uniform than that fabricated by early pouring matrix alloy. The grain of composites is becoming smaller with the increase of squeeze casting pressure, but it is not obvious that the SiC foam reinforcement decreases the effect of squeeze pressure on microstructure of matrix. The size of grain is not obviously changed, but the morphology of grain is obviously changed when the reinforcement is joined into the matrix alloy. The column a-Al dendrites perpendicular to the struts of SiC foam are easily gotten as the aperture of reinforcement is smaller. When the composites start to solidify, the primary α-Al column dendrites appeared first near the strut of SiC foam and then grew into the center of aperture. At last, the eutectic silicon appeared at the center of aperture where different direction column a-Al dendrites gather before the eutectic reaction occurred at the surface of strut.更多还原