富铈混合稀土变质作用

The Effect of Mixed Rare-earth Enriched with Cerium on the Modification

研究了富铈混合稀土对铝硅合金的变质作用。试验用高纯工业铝錠A00和高纯多晶硅(>99.99%,质量分数,下同)配制Al-10%Si的铝硅合金,加入富铈混合稀土进行变质处理,在不同冷却条件下进行凝固。对其进行显微组织观察及电子显微分析表明:该稀土能使共晶硅变成扭曲的密集分枝的纤维状,且冷却速度愈快,组织愈细;变质后的共晶硅内孪晶的存在并不必然,且大多数情况下的共晶硅晶体内不存在孪晶,但硅晶体仍可分枝细化;硅枝的生长位向并不固定。

Al-10%Si alloy, made of high purity industrial aluminum and high purity polycrystal silicon (>99.99%), was modified by mixed rare-earth enriched with cerium. Then the alloy solidifies under different cooling condition. Observing its microstructure and applying electronic microscopic analysis,conclusion was drawn that the mixed rare-earth enriched with cerium not only makes the alloy form flex closely branching fibrous eutectic Si-phase, but also fine with the increasing rate of cooling. The two phases in modified eutectic have no coherence of high-preferred orientation. There is no twin crystal in eutectic Si-phase.