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研究了Na盐、La和Na盐+La复合变质对Al-10Si合金组织与硬度的影响,分析了Na盐、La的变质机制。研究发现,Al-10Si合金经Na盐+La复合变质后,宏观组织中晶粒细小呈等轴状,退火后晶粒粗化不明显;显微组织中共晶Si分枝、细化,趋于纤维状,初生α枝晶趋于熔断且呈等轴状,共晶组织与初生α相间的界面趋于清晰且平整;退火对经Na盐+La复合变质的Al-10Si合金的组织形态影响较小;变质处理提高了Al-10Si合金的硬度。研究认为Na盐变质机制在于触发共晶Si孪晶并不断封锁孪晶凹槽;La变质机制在于其在固液界面前沿的富集改变了共晶Si的生长特征。
The effects of Na, La, Na + La composite microstructure on the microstructure and hardness of Al-10Si alloy were studied. The metamorphic mechanisms of Na salt and La were analyzed. The results show that the grain size of Al-10Si alloy is equiaxed and the grain coarsening is not obvious after annealing. The eutectic Si of the Al-10Si alloy is thinned and refined in the microstructure Fibrous, primary α dendrite tends to fuse and equiaxed, eutectic microstructure and the primary α phase tends to be clear and smooth interface; annealing Na-La + La compound metamorphic Al-10Si alloy morphology than Small; metamorphic treatment to improve the Al-10Si alloy hardness. It is believed that the mechanism of Na salt alteration is to trigger eutectic Si twins and block the twin grooves ceaselessly. The mechanism of La metamorphism lies in that its enrichment at the solid-liquid interface changes the growth characteristics of eutectic Si.