中文摘要：

研究了亚共晶或过共晶Al-Cu和Al—Si合金在．5GPa压力条件下凝固的显微组织特征。与常压相比，高压不仅会明显改变凝固组织形态，而且会使凝固组织尺寸发生变化，有时粗化，有时细化。凝固组织粗化还是细化与压力对液固两相区温度间隔的影响有关。当压力使液固两相区温度间隔增大时，凝固组织粗化，反之细化。此外，还提出了一种针对树枝晶和胞状晶两种不同形态组织的尺寸评价新方法。

英文摘要：

The microstruetures of hypoeutectic and hyper-eutectic Al-Cu and Al-51 alloys solidified at high pressure （5 GPa） were investigated. The results showed that high pressure had an evident influence on the morphologies and the dimensions of the solidified microstructures. This influence is directly related to the temperature interval of the liquid-solid region in the phase diagram. When the temperature interval is increased by pressure, the solidified microstructure will be coarsened. When the temperature interval is decreased by pressure, the solidified microstructure will be refined. Moreover,a new method is proposed to easily evaluate the sizes of the cellular and the dendritic microstructures.