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利用光学及扫描电子显微技术、X射线择优取向分析等手段对Al-Si合金的形貌、取向等特点进行了研究.结果表明:在自由凝固下,作为生核与领先相的硅晶体形态与凝固速度密切相关.在较低凝固速度下((几-几十)厘米/小时)硅晶核呈{111}面围成的八面体形态,择优生长方向为<100>;而在较高凝固速度下((几十-几百)厘米/小时)硅晶核呈{100}面围成的六面体形态,择优生长方向为<111>;中等凝固速度下的硅晶核具有由{100}和{111}面共同围成的复杂形态.共晶团生长过程中,硅相的分枝机制主要表现为择优生长方向的分枝,而缺陷的作用是次要的.
The morphology and orientation of Al-Si alloy were investigated by means of optical and scanning electron microscopy (SEM) and X-ray preferred orientation analysis. The results show that the morphology of the Si-Al alloy Which is closely related to the solidification rate.The silicon nuclei at the lower solidification rate ((a few to several dozen) cm / h) are surrounded by an {111} facet octahedron with a preferred growth direction of <100> The solidification rate of ((tens to hundreds) cm / h) of silicon nuclei is {100} surrounded by hexagonal morphology, the preferred growth direction of <111>; And {111} planes, the branching mechanism of the silicon phase mainly appears as the branch of the preferred growth direction during eutectic growth, and the effect of defects is secondary.