稀土在过共晶Al-Si合金中的变质作用

Modification Mechanism of Hypereutectic Al-Si Alloy Treated with Rare Earth Metals

分析了稀土合金变质处理过共晶铝硅合金硅相的形态变化过程。认为稀土除能细化共晶硅外,也能细化初生硅,是一种优良的变质剂。RE的变质机制与Na不同,稀土是通过造成硅相前沿大的成分过冷来促进硅晶分枝而达到变质目的的。

The process of shape change of Si crystals in the hypereutic Al-Si alloy modified with rare-earth metals is investigated. It is supposed that the modification mechanism of RE is different from that of Na in the fact that RE causes constitutional under-cooling in the solidifying front of Si crystals and results in a change of grouth morphology of Si from plate into fibrous form.