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研究了单一和复合Al-5Ti-B、RE和Al-10Sr细化变质剂对砂型铸造Al-7.5Si-4Cu合金力学性能、显微组织、细化变质效果及其金属间化合物变化的影响。结果表明:与单一细化变质处理以及铸态相比,经过添加质量分数为0.8%的Al-5Ti-B、0.1%的RE和0.1%的Al-10Sr细化变质剂复合细化变质处理后铸造Al-7.5Si-4Cu合金的力学性能和显微组织都得到了显著改善。对于单一细化变质处理,加入0.8%的Al-5Ti-B中间合金后,合金的抗拉强度和布氏硬度得到大幅度提高,并且细化了α(Al)相。加入0.1%的RE中间合金后,合金的伸长率得到了最大程度的提高。这是因为RE的加入使铝合金熔液而得到净化,同时改变了金属间化合物的形状。而加入0.1%的Al-10Sr变质剂后,合金的屈服强度得到改善,但其他性能的改善有限。Al-10Sr变质剂对共晶硅具有较强的变质作用,但使得铝合金熔体含气量增加并形成严重的柱状晶组织。利用硅相的平均面积和长宽比描述细化变质效果得到的结论与力学性能和组织分析的结果相同。
The effects of single and composite Al-5Ti-B, RE and Al-10Sr refinement modifiers on the mechanical properties, microstructure, refinement and metamorphism of the as-cast Al-7.5Si-4Cu alloy and its intermetallic compounds were investigated. The results show that compared with the single refinement treatment and the as-cast state, the Al-5Ti-B with mass fraction of 0.8%, the RE with 0.1% RE and the Al-10Sr refinement agent with 0.1% Casting Al-7.5Si-4Cu alloy mechanical properties and microstructure have been significantly improved. For single refinement metamorphism, the addition of 0.8% Al-5Ti-B master alloy, the tensile strength and Brinell hardness of the alloy is greatly improved, and the refinement of the α (Al) phase. After adding 0.1% RE master alloy, the elongation of the alloy has been maximized. This is because RE is added to melt the aluminum alloy to be purified while changing the shape of the intermetallic compound. The addition of 0.1% Al-10Sr modifier, the yield strength of the alloy is improved, but the other performance improvement is limited. Al-10Sr modifier has a strong metamorphic silicon metamorphism, but makes the aluminum alloy melt gas content and the formation of serious columnar crystalline structure. The results obtained by using the average area and aspect ratio of the silicon phase to describe the metamorphic effect are the same as those of the mechanical properties and the microstructure analysis.