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对粉末冶金法制备的20%SiCp/2009Al(体积分数)复合材料进行了一次挤压和二次挤压,对2种挤压棒材微观结构的观察表明,相对于热压复合材料,挤压可以减少SiC_p团聚;而二次挤压可进一步细化SiC_p,使SiC_p沿挤压方向定向分布,增大SiC_p的长径比,但对基体合金晶粒尺寸和〈111〉织构影响不大.此外,二次挤压使SiC_p沿挤压方向的平均间距进一步增大,更易于产生近似垂直于挤压方向的贫SiC_p层,导致复合材料屈服和抗拉强度下降而延伸率增加.
The microstructure of 20% SiCp / 2009Al (volume fraction) composites prepared by powder metallurgy method was extruded once and twice. The microstructure observation of the two kinds of extruded bars showed that compared with the hot-pressed composites, Which can reduce the SiC_p agglomeration. However, the secondary extrusion can further refine the SiC_p and orient the SiC_p along the extrusion direction, increasing the aspect ratio of SiC_p, but has little effect on the grain size and 111 texture of the matrix alloy. In addition, the secondary extrusion further increases the average spacing of SiC_p along the extrusion direction, which makes it easier to produce a lean SiC_p layer approximately perpendicular to the extrusion direction, resulting in a decrease in yield and tensile strength of the composite with an increase in elongation.