通过分析快速凝固高硅铝合金粉末在热挤压过 程中的密度、 微观组织和相结构的变 化， 对粉末热挤压成形机理进行了探讨。 结果表明， 快速凝固高硅铝合金粉末 热挤 压过程分为2个阶段， 即填充挤压阶段和稳态流动阶段， 粉末生坯的致密化主要在第一 阶段完成。 粉末颗粒中初晶Si相受到加热长大和挤压破碎两方面的综合作用， 最终得到的 挤压材料中 的 Si颗粒与原始粉末相比没有明显的粗化。 合金的相组成在挤压前后没有发生变化， 快速凝 固合金的组织结构特征基本得以保留。
By analyzing the changes of the density， micr ostructures and phase durin g the hot extrusion process of rapidly solidified (RS) hypereutectic aluminum-s i licon powder， the mechanism of powder hot extrusion was studied. Experimental re sults show that the powder hot extrusion process can be divided into two sta ge s， hot compress process and stable flow process. The density of the billet increases greatly at the firs t process. Two effects decide the primary silicon particle size: gr owing due to heating and breaking due to extrusion. However， no change of phas e is detected after hot extrusion， and the powder's RS characteristics remain un changed.
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