研究了机械搅拌对过共晶 Al- 17% Si- 4.5 % Cu- 0 .5 % Mg合金半固态组织的影响。试验结果表明 :机械搅拌使初晶硅在剪切力作用下发生弯曲和破碎 ,并相互碰撞、集聚、合并长大 ,由板片状向多面体形转变 ;在固液两相区进行变温机械搅拌 ,冷却速度对初晶硅的颗粒直径有着重要的影响 ,随着冷却速度的增大 ,初晶硅的颗粒直径减小 ,当冷却速度为 5℃ / min时 ,初晶硅的颗粒直径小于 45μm,同时出现近球形的α相 ,获得了非常理想的半固态组织 The effect of mechanical stirring on the semi-solid microstructure of hypereutectic Al-17% Si-4.5% Cu-0.5% Mg alloy was investigated. The experimental results show that the mechanical stirring causes the primary silicon to bend and crush under the action of shearing force, collide with each other, aggregate, merge and grow, and change from sheet to polyhedron; , The cooling rate has an important influence on the particle diameter of the primary silicon. As the cooling rate increases, the primary particle diameter decreases. When the cooling rate is 5 ℃ / min, the primary particle diameter is less than 45μm , At the same time appear nearly spherical alpha phase, obtained a very ideal semi-solid tissue