【摘要】 采用正交实验设计方法研究了Al-21Si-1.5Cu-1.5Ni-2.5Fe-0.5Mg合金P+Sr+Ce复合变质。正交实验表明变质剂的最佳加入量(质量分数)为:2%(CaH2PO4+2CaSO4)+0.2%Sr+0.2%Ce,可一次细化初晶硅与共晶硅,并改善富铁相形态。X射线衍射分析与能谱分析表明,未变质合金中的针状富铁相为Al9FeSi3,复合变质使粗大针状富铁相消失,生成鱼骨状富铈富铁相Al8CeFe4。在最佳变质条件下,室温抗拉强度与300℃瞬时抗拉强度均比未变质合金提高约30%,扫描电镜观察发现拉伸断口由脆性的沿晶断裂变为混合断口,断口中有大量韧窝存在。更多还原

【Abstract】 The P+Sr+Ce compound modification technologies of as-cast Al-21Si-1.5Cu-1.5Ni- 2.5Fe-0.5Mg alloy were investigated by means of orthogonal test. Orthogonal test results show that 2% （CaH₂PO₄+2CaSO₄）+0.2%Sr+0.2%Ce is the optimum additive of modification treatment which can fine eutectic and primary silicon also can change the form of rich-iron phase at same time. The needle form of rich-iron phase is （Al₉FeSi₃）, which is proved by X-ray diffraction analysis and X-ray energy spectrum analysis. After compound modification treatment, the needle form of rich-iron phase disappeared and the fish bone form of rich-iron and rich-Ce phase that is Al₈CeFe emerged. Both at room temperature and at 300 ℃, the tensile strength of the alloy after the modification treatment with the optimum additive is 30% lager than that of the alloy unmodified. Observed by SEM, the brittle intercrystalline tensile fracture changed into a blended one in which has many dimples.更多还原