对3种典型铝硅合金熔体温度处理的对比分析

Comparision analysis of melt temperature treatment of three typical Al-Si alloy

对3种典型成分的铝硅合金(Al 20%Si、Al 12%Si和Al 7%Si)进行了熔体温度处理凝固组织变化规律的比较研究。结果表明:在Al 12%Si共晶合金熔体处理组织中存在α枝晶与初晶硅共存以及α枝晶在一定处理条件下可以完全消失的现象;3种成分Al Si合金的α枝晶及初晶硅的形态尺寸随过热温度、静置时间增加出现周期性的变化规律,出现最小尺寸的温度、时间并不完全一致;熔体温度处理对Al 7%Si中枝晶大小、形态等有一定影响,但细化效果不明显。在铝硅合金中,硅原子微观有序团簇和铝有序偏聚原子团簇可能存在于不同的温度区间,铝有序偏聚原子团簇存在的温度区间更靠近温度轴,硅原子微观有序团簇具有比铝有序偏聚原子团簇更强的结合能。

The solidification microstructures of hypoeutectic, eutectic and hypereutectic Al-Si alloys by melt temperature treatment were studied comparatively. The results show that, in the microstructures of Al-12%Si alloy, dendrites of α phase coexist with pre-precipitate silicon, and under a certain treatment condition, dendrites of α phase would disappear; the sizes of dendrite of α phase and pre-precipitated silicon change regularly with increasing temperature or time, the temperature and time that the smallest sizes of the phases appear among the alloys is not corresponded; the melt temperature treatment have certain effect on the sizes of dendrite of α phase, but the effect is limited. It is considered that in the TTT diagram of liquid structure and temperature of Al-Si alloys, silicon atom clusters and aluminum atom clusters would exist in different temperature zones, the position of aluminum atom clusters is closer to temperature axis than that of silicon atom clusters, the bond energy of the silicon atom clusters is the stronger than that of aluminum atom clusters.