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研究了La、Pr复合变质对铸造Al-Cu合金的时效硬度、室温力学性能和高温力学性能的影响,并探讨了稀土变质Al-Cu合金的作用机理。结果表明,随着时效温度的升高,未变质和复合变质的Al-Cu合金的峰值硬度都呈现逐渐降低的趋势;在同一时效温度下,Al-Cu合金峰值硬度从高至低顺序依次为:0.2%La+0.1%Pr变质合金>0.15%La+0.15%Pr变质合金>0.1%La+0.2%Pr变质合金>未变质合金;三种不同复合变质Al-Cu合金的室温抗拉强度和断后伸长率都要高于未变质处理的Al-Cu合金,且0.2%La+0.1%Pr复合变质的Al-Cu合金取得了最佳的强度与塑性结合。0.2%La+0.1%Pr复合变质的Al-Cu合金的高温性能优于未变质Al-Cu合金。La和Pr复合变质可以使Al-Cu合金的铸态组织得到有效细化;0.2%La+0.1%Pr复合变质Al-Cu合金在固溶时效处理后,θ’析出相的平均尺寸要比未变质Al-Cu合金小,且数量明显增多。
The effects of La and Pr metamorphism on the aging hardness, mechanical properties at room temperature and mechanical properties at high temperature of cast Al-Cu alloy were studied. The mechanism of the modification of Al-Cu alloy was also discussed. The results show that with the increase of aging temperature, the peak hardness of unmodified and compound metamorphic Al-Cu alloy shows a decreasing trend. Under the same aging temperature, the order of peak hardness of Al-Cu alloy from high to low is : 0.2% La + 0.1% Pr metamorphic alloy> 0.15% La + 0.15% Pr metamorphic alloy> 0.1% La + 0.2% Pr metamorphic alloy> unmodified alloy; room temperature tensile strength of three different metamorphic Al-Cu alloys and The elongation after fracture was higher than that of Al-Cu alloy without modification, and the combination of 0.2% La + 0.1% Pr metamorphic Al-Cu alloy obtained the best strength and plasticity. The high temperature performance of Al-Cu alloy with 0.2% La + 0.1% Pr composite modification is better than that of unmodified Al-Cu alloy. La and Pr composite metamorphism can effectively refine the as-cast microstructure of Al-Cu alloy. The average size of θ ’precipitated phase after solution-aging treatment in 0.2% La + 0.1% Metamorphic Al-Cu alloy is small, and the number increased significantly.