【摘要】 亚共晶Al-Si合金中，Si相的生长机制已经有很多研究，但至今仍然存在分歧。利用扫描电镜、透射电镜等手段研究了不同冷却速率下亚共晶Al-Si合金中Si相的三维形貌，以及Si生长末端的形貌及其微观结构。结果表明，随着冷却速率的提高，共晶Si的尺度进一步减小，分枝更为发达，但仍呈板片状。共晶Si的生长末端的特征主要有棱面端部、凹角端部、小面端部。对小面端部的衍射花样分析并没有典型的双斑点衍射花样，因此，提出了台阶凹角机制来解释共晶Si片状生长行为。更多还原

【Abstract】 In hypo-eutectic Al-Si alloys, the growth mechanism of Si phase has been studied a lot, but it is still inconclusive. In this paper, scanning electron microscopy and transmission electron microscopy are used to study the three-dimensional morphology of Si phase under different cooling rates, as well as the morphology of Si growth end. The results show that with the increase of cooling rate, the size of eutectic Si is further reduced and the branching is more developed, but it is still plate-like. The characteristics of the growth end of eutectic Si mainly include facet end, concave corner end and facet end. There is no typical double-spot diffraction pattern of the diffraction pattern at the end of the facet. Therefore, this paper proposes a step concave angle mechanism to explain the growth behavior of eutectic Si.更多还原