稀土在铝硅合金中细化和变质作用微观机制

Delication and modification micromechanism of rare earth in alusil alloy

采用单向凝固装置和光学、电子金相等研究分析手段 ,研究了稀土对铝硅合金中两相形态的作用规律。结果表明 :无论对α -Al相还是对硅相 ,稀土都不表现出明显的形核作用。在铸态组织中 ,硅相主要富集于铝硅两相界面上 ,通过影响生长过程而影响二元组织的形态。稀土的加入使α -Al的二次枝晶细化 ,同时使硅由板片状转变为细小的纤维状 ,并在后续热处理中转变为颗粒状。对合金的性能特别是韧性产生很好的影响。

WT5”BZ]Using the research analytical methods such as one way solidified divice,optics,electronic metallography and so on,the functional law of the rare earth on the two phrase form in the alusil alloy has been studied.The results shows no matter how α Al is phrased or Si is phrased,the rare earth does not show the distinctive form nucleaon function.In the as cast structure,the silicon phrase mainly focuses on the two phrase interface of alpax.It effects pattern of the binary structure by influencing the growth process.The addition of the rare earth lets the secondary dendrite of α Al delication,meanwhile,makes silion turn into tiny threadiness from clintheriform and changes into graininess in the follow up hot treatment.It has a good effect on the property of alloy,especially tenacity. [WT5”HZ]