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    镧添加量对再生Al-9Si-1Fe合金组织细化及性能的影响

    Effect of La Addition Amounts on Microstructure Refinement and Properties of Recycling Al-9Si-1Fe Alloy

    • 摘要: 以工业纯铝、Al-50Fe、Al-20Si和Al-20La中间合金为原料进行熔配,经2 000 W功率超声处理后浇注制备再生Al-9Si-1Fe-xLa合金(x=0,0.1,0.2,0.3,0.4,0.5,质量分数/%),研究了镧添加量对合金显微组织、力学性能及摩擦学性能的影响。结果表明:随着镧添加量增加,合金组织中α-Al的二次枝晶间距、共晶硅的长宽比以及富铁金属间化合物的长度均先减小后增加,当镧添加量(质量分数)为0.3%时最小,分别为5.4 μm,1.00,4.5 μm,该添加量下组织的细化效果最好。随着镧添加量的增加,合金的硬度提高,抗拉强度和断后伸长率均先增后减,平均摩擦因数先减后增;当镧添加量从0增至0.3%时,磨损率从1.37×10−2 mm3·N−1·m−1降0.85×10−2 mm3·N−1·m−1,降幅达38%。当镧添加量为0.3%时,抗拉强度和断后伸长率最大,分别为224 MPa和2.28%,平均摩擦因数最低。

       

      Abstract: The recycling Al-9Si-1Fe-xLa alloys (x=0, 0.1%, 0.2%, 0.3%, 0.4% and 0.5%, mass fraction/%) were prepared by melting industrial pure aluminum together with Al-50Fe, Al-20Si, and Al-20La master alloys, followed by ultrasonic treatment at 2 000 W power before casting. The effects of La addition amounts on the microstructure, mechanical properties and tribological properties of the alloys were studied. The results show that with increasing the addition amount of La, the secondary dendrite arm spacing of α-Al, the aspect ratio of eutectic silicon, and the length of Fe-rich intermetallic compounds in the alloy all decreased first and then increased; when the La addition amount (mass fraction) was 0.3%, they reached the minimum values of 5.4 μm, 1.00 and 4.5 μm respectively, and the microstructure refinement effect was the best at this addition level. As the La addition amount increased, the hardness of the alloys was improved, the tensile strength and elongation after fracture first increased and then decreased, and the average friction coefficient first decreased then increased. When the addition amount of La increased from 0 to 0.3%, the wear rate decreased from 1.37×10−2 mm3·N−1·m−1 to 0.85×10−2 mm3·N−1·m−1, with a reduction of 38%. When the La addition amount was 0.3%, the tensile strength and elongation after fracture reached the maximum values of 224 MPa and 2.28%, and the average friction coefficient was the lowest.

       

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