P变质对不同冷速下过共晶压铸铝合金初晶Si的影响

以过共晶压铸铝合金为对象，研究了P变质对不同冷却速度下初晶Si组织的影响。发现P变质处理前后随冷却速度的增加，初晶Si尺寸减小的变化趋势十分相似，并且都存在一个明显的突变区域。对于不同冷却速度下合金组织的细化，P变质都有很好的促进作用。同一冷却速度下，P变质后细化效果可增加42．7％，在冷却速度很高（铸件厚度达到1mm）时，P变质对初晶Si仍然具有很好的细化作用。在快速凝固和P变质双重作用下，初晶Si组织得到更加明显的细化。Al—P中间合金是一种良好的过共晶压铸铝合金变质剂。

Effects of P Modification on Primary Si in Hypereutectic Al-Si Die Casting Alloy with Different Cooling Rates

Effects of P modification on primary Si in hypereutectic Al-Si die casting alloy with different cooling rates were investigated. It is revealed that the tendency of size decrease of primary Si in hypereutectic Al-Si alloy after and before P modification is very similar with increasing in cooling rate, where both have a sharp transition zone. P modification can greatly promote the refinement of the primary Si in the alloy with different cooling rates, because there exists a region between two change curves of primary Si size after and before P modification. Under the same cooling rate conditions, the refinement effects can be improved by 42.7% after P modification, and P still as good modification effects on primary Si with high cooling rate ( casting thickness of 1mm). The size of primary Si can be significantly refined with P modification under rapid solidification conditions. Al-P master alloy is an excellent modifier for hypereutectic Al-Si die casting alloy.