液淬和变质工艺对过共晶铝硅合金的影响

Effect of melt-quenching and modification on Al-Si hypereutectic

过共晶铝硅合金中的初晶硅由于晶粒粗大并且有尖锐的棱角,严重削弱了合金的机械性能,通常我们采用变质处理工艺来改善这一现象。液淬工艺主要用于得到非晶组织,通过液淬工艺能得到超细非晶结构。如果把液淬工艺加入到变质工艺的过程中,这对实验的结果一定能产生影响。本文中,我们分别对过共晶铝硅合金采用了变质和变质液淬的混合工艺。通过实验我们证实磷元素能够显著改变组织的尺寸,通过对磷元素的扫描分析,发现磷元素不仅分布在中心,在初晶硅的内部也分布大量的磷元素,这说明了磷元素除了在异质形核中起作用外,它还可以把初晶硅分割为很多小的初晶块,不同的小初晶块生长方向各不相同,那么在宏观上观察,经过磷元素变质的初晶硅,形状上开始变得比较圆滑。如果我们在变质过程中引入液淬工艺,变质效果能得到显著的提高,结果表明晶粒尺寸变小,晶粒形状变为椭圆,这说明冷却速度促进了磷元素对初晶硅尺寸和形状的影响。

Primary Si phases exist in Al-Si Hypereutectic which harm the mechanical performance because of crassitude and edges.The modification technology is always adopted to improve its performance.Melt-quenching is used to produce the amorphous alloy.After melt-quenching we can get ultrafine structure.If we introduce the melt-quenching into the modification process,it must affect the result of modification.In this paper Al-Si Hypereutectic is done under modification and modification-melt-quenching respectively.The result proves that melt - quenching can improve the microstructure of the modification. Through the scan of phosphorus they exit in the internal and center of primary Si. It proves phosphorus can be served as not only impurity but also divided the primary Si into small pieces. Many small pieces have defferent direction so in the whole the primary Si is smooth. Compound with the Melt - quenching the size is smaller and shape is more smooth. It proves melt - quenching can increase the effect of modification.