铸造SiC_p/Al-Si复合材料中的“界面Si”行为

“INTERFACIAL Si” BEHAVIOR IN CAST SiC P/Al Si COMPOSITES

采用ＴＥＭ 研究了ＳｉＣ／ＡｌＳｉ 复合材料， 提出了“界面Ｓｉ”的概念。由于与增强体ＳｉＣ 不润湿， 初生α（Ａｌ） 相不在ＳｉＣ 颗粒上形核并对其发生排斥。（Ａｌ＋ Ｓｉ） 共晶体中的共晶领先相Ｓｉ 优先在ＳｉＣ表面上形核、长大， 形成界面Ｓｉ， 并形成大量ＳｉＣ／Ｓｉ 界面。ＳｉＣ／Ｓｉ 界面“干净”、平直， 结合紧密， 其中未发现任何界面相。在个别ＳｉＣ／Ａｌ 界面上析出了二次Ｓｉ。

SiC p/Al Si composites were studied by means of conventional TEM. The conception of “interfacial Si” was proposed. Because of the nonwetting between liquid metal and reinforcing particles, primary α phase rejects SiC particles and does not nucleate on them. It was discovered that the leading phase Si in the (Al+Si) eutectic tends to nucleate and grows preferentially at the SiC surface, thus forming the characteristic “interfacial Si”, and the SiC/Si interfaces. The SiC/Si interfaces are found to be smooth, clean and closely bonded; no voids, reaction layers or other interfacial phases are found at the interfaces except the “interfacial Si”. Beside the large side eutectic Si, tiny Si particles were also found precipitate in some SiC/Al interfaces, forming the “secondary Si precipitates”.