Sip／Al复合材料中的界面和硅相形貌的演变

Evolution of silicon phase configuration and Si-Al interface of Si_p/Al composites

采用金相显微镜、透射电子显微镜和高分辨电镜等手段,研究不同高温真空热处理工艺条件下,高体积分数Sip/Al复合材料(φ(Si)=65%)中硅铝界面特征与硅相形貌的演变过程。结果表明:热处理过程中硅相形貌演变为尖角钝化的颗粒状、球化的孤岛颗粒状和三维网络结构状。基于扩散理论将硅相形貌的演变分为3个阶段:不规则形状硅颗粒的尖角逐渐溶解到铝合金中,发生颗粒的钝化现象;较小硅颗粒周围逐渐溶解在铝合金中的硅在浓度梯度的作用下,通过扩散逐渐在较大硅颗粒周围析出并长大;长大的硅颗粒互相接触联结,形成网状结构。铸态Sip/Al复合材料中Si-Al界面平直,干净,无析出物,同时存在大量位错;高温热处理后的Si-Al界面变得圆滑,界面附近有细小的硅相析出物存在,几乎不存在位错。

The evolution of silicon phase configuration and Si-Al interface in Sip/Al composites （φ（Si）=65%） fabricated by squeeze casting technology during high temperature heat-treatment were investigated. The rnicrostructure was observed by optical microscopy, transmission electron microscopy and high resolution electron microscopy. The results show that the silicon phase configuration becomes round, annular and reticular. The configuration evolution is based on the diffusion of silicon atoms, and the process is comprised of three parts as follows： the irregular comers and edges of silicon particles are dissolved, the silicon atoms dissolved from smaller particles diffuse to larger particles, because of the concentration gradient exists between them, and the larger particles grow up, then the grown particles connect with each other, and form network configuration silicon. The Si-Al interface of composites is straight and free from interfacial reaction products, lots of dislocations are found. But after the heat treatment, the interface becomes smooth and dislocations disappear. Around the interfaces, fine silicon phases precipitate.