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通过SEM、XRD等分析手段研究了A392合金的P-RE复合变质效果,重点研究了RE元素在A392合金中的形态、分布及其对初晶硅的细化变质机理。结果表明,使用0.08%的P、1.1%的RE复合变质时效果最好,初晶硅平均直径达到19.4μm。RE能在P细化的基础上进一步细化初晶硅,可能是因为RE在Si生长界面前沿富集,阻碍Si原子的扩散,加大了成分过冷,使其生长界面呈现不稳定状态,限制了初晶硅的长大。过量的RE会导致合金中出现大量的RE富集物,不但会降低初晶硅细化效果,而且还降低合金的力学性能,因此,采用P-RE复合变质时,需要严格控制RE含量。
The effect of P-RE composite modification on A392 alloy was studied by means of SEM and XRD. The morphology and distribution of RE element in A392 alloy and the mechanism of refinement and metamorphism of primary Si were studied. The results show that 0.08% P and 1.1% RE are the best modifiers, and the average primary crystal diameter reaches 19.4μm. RE can further refine the primary silicon on the basis of P refinement, probably because RE is enriched in the front of the Si growth interface, hinders the diffusion of Si atoms, increases the component overcooling, and makes the growth interface unstable, Limiting the growth of primary silicon. Excessive amount of RE can lead to a large amount of RE enrichment in the alloy, which not only reduces the primary silicon refinement effect but also reduces the mechanical properties of the alloy. Therefore, the RE content needs to be strictly controlled in the P-RE composite metamorphism.