P-RE复合变质对过共晶Al-20%Si-Mg合金凝固组织的影响

Influence of complex modification agent P-RE on solidification structure of hypereutectic Al-20%Si-Mg alloy

以过共晶Al-20%Si-Mg合金为研究对象,利用金相显微镜分析了不同成分配比的P-RE复合变质剂对合金凝固组织的影响。试验结果表明,P-RE复合变质剂对过共晶Al-20%Si-Mg合金的初晶硅和共晶硅均有良好的变质和细化作用,当变质剂配比为0.06%P+0.8%RE时,合金取得最好的变质效果,初晶硅由粗大的多边形块状变为钝化角状、块状或近球形,且分布更为均匀,平均尺寸由未变质的82.3μm细化到15.2μm;共晶硅由长的粗针状转变为颗粒状或短棒状,平均尺寸由未变质的9.1μm细化到3.6μm。

Different proportion of P-RE complex modification agent were introduced to modify hypereutectic Al-20%Si alloy,the influence of complex modification on the solidification structure of hypereutectic Al-20%Si-Mg alloy have been investigated by metallographic microscope.The results show that both primary crystal silicon and eutectic silicon of the hypereutectic Al-Si-Mg alloy can be modified excellently by the P-RE complex modifier,the primary crystal and eutectic are refined.By adding 0.06% P＋0.8% RE,the optimal modification effect can be obtained.Original coarse block and polygon primary crystal silicon size is decreased,their edges and angles are passivated with an average size changed from 82.3 μm to 15.2 μm.and the refined primary crystal silicons are evenly distributed in the matrix.The large needle eutectic silicons are converted to fine lamella or particle ones with an average size changed from 9.1 μm to 3.6 μm.