半固态加工Al-Zn-Mg合金的组织演化

选用SIMA法制备的LC4合金及液相线凝固法制备的LC9合金为原料，研究了半固态加工Al-Zn-Mg合金的组织演化。由于这两种方法制备半固态坯料的机理完全不同，因此这两种材料加工后的组织演化规律截然不同：LC4合金的晶粒尺寸由于聚结而长大，而LC9合金的显微组织没有明显的变化。借助于扫描电镜和能谱分析，对半固态加工前后的显微组织进行成分分析，结果表明晶界处由共晶区、低熔点的富Cu区和杂质区三部分组成，且LC9合金的再加热组织的液相薄膜厚度大于CL4合金的；半固态加工后制件各部分的成分基本一致，证明半固态加工形成过程中材料的流动方式为层流。

Micostucture Evolution of AI-Zn-Mg Alloy in Semi-solid Tate During Hou Working

The prepared LC\-4 billet with SLMA technology and LC\-9 billet with liqudius-quenching were used to investigate microstructure evolution of Al-Zn-Mg alloy in semi-solid state during hot working. The law of microstructure evolution for the two kinds of alloy in semi-solid state during hot working was quite different because the SLMA technology was fully different from liqudius quenching. Grain size of LC\-4 grew up due to coalescence while the microstructure of LC\-9 didn' t show any evident change. Microstructural component after and before hot working semi-solid state was analyzed by SEM and energy spectrum analysis. The results showed that the grain boundary was composed of eutectic area, area rich in Cu with low melting point and impurity area. Moreover, the liquid film of reheating microstructure for LC 9 alloy was thicker than for LC 4 alloy, and the composition of the workpiece in different part in semi-solid state after hot working is basically even, which has verified the lamellar flow model for the billet in semi-solid state during hot working.