采用金相观察和X射线衍射分析方法研究了Al-Sr,Al-P,Cu-P三种变质剂对高硅(22%,质量分数)铝合金标准样品组织均匀性的影响。结果表明:未添加变质剂的标准样品中初晶硅呈粗大板片状,且局部聚集成团,组织均匀性差;添加了Al-Sr变质剂后初晶硅得到了一定的细化,但共晶硅高度分枝,组织分布仍不够均匀;添加Al-P和Cu-P变质剂后,标准样品中出现了新相AlP,使得初晶硅由板片状变成了细小的多边形颗粒,且弥散分布于整个基体中,同时共晶硅析出明显减少,而初晶硅数量增多,标准样品的组织均匀性好。另外对比发现,添加Cu-P变质剂后的改善效果最为显著,组织均匀性最好,且其成分均匀性通过传统的极差法检测也完全符合标准样品的要求。本工作从组织均匀性上为高硅铝合金标准样品的制备提供了新的判据和参考。
The influences of Al-Sr,Al-P,Cu-P modifier on microstructure uniformity of high-silicon(22%,mass fraction) aluminum alloy standard samples were investigated by using the optical microscopy and X-ray diffraction.The results show that the microstructure uniformity of the standard sample without modifying is poor because the primary crystal silicon is large sheet and gathers into cluster.After adding Al-Sr modifier,the microstructure of the standard sample is shown to be unsatisfactory uniformity because the primary crystal silicon gets a certain degree of refinement,but the eutectic silicon has a high degree of branching.After adding Al-P and Cu-P modifier,the microstructure of the standard sample is homogeneous because new AlP phase making the primary crystal silicon change from the board sheet into a small polygonal particle and amount increases when the eutectic silicon is reduced.In addition,it can be founded that after adding Cu-P modifier the improvement is more remarkable and the uniformity of organizations is better.Also the uniformity of the composition meets the requirement for standard sample even tested by the traditional range-method.This work can provide new criterion and reference for preparation of standard sample of high-silicon aluminum alloy according to the microstructure uniformity.