含Zr,Ce稀土元素铝合金导线的微结构与导电性能研究

Microstructure and Electrical Conductivity of Al Alloy Wire with Zr and Ce

Al-Mg-Si铝合金作为常用架空导线,既要有较高的强度也要保证其较高的导电率。在固溶状态下,Al-Mg-Si-Ce合金有较多无法回溶基体的含Ce粗大第二相,这些黑色的第二相主要分布在晶界处,降低合金的塑韧性和强度。而Al-Mg-Si-Zr合金中几乎没有第二相。固溶处理能够使含Zr的第二相断裂、溶解,非平衡组织消失。时效温度为180℃,时效时间为2~24 h时,Al-Mg-Si-Zr合金导线导电性优于Al-Mg-Si-Ce合金。在时效时间内,Al-Mg-Si-Zr合金的导电率从53.07%IACS提升至60.63%IACS,而Al-Mg-Si-Ce合金的导电率仅从53.23%IACS提升至58%IACS。通过透射电子显微镜(TEM)分析观察,发现Zr元素会促进β"(Mg5Si6)沉淀相的析出,并且生成了Al3Zr沉淀相。这两种相的析出极大的减小了合金内部电子散射,增加了电子平均自由程,从而提高了Al-Mg-Si-Zr的导电率。

As an overhead conductor of aluminum alloy,Al-Mg-Si should not only possess high strength,but also have high conductivity.There were many coarse secondary phases containing Ce of Al-Mg-Si-Ce alloy in the solid solution state,and these black second phases were distributed at grain boundaries,which would reduce the plasticity and strength of Al-Mg-Si-Ce alloy.While there were almost no secondary phases in the Al-Mg-Si-Zr alloy.After solid solution heat treatment,the second phases contained Zr were broken and dissolved,and the non-equilibrium structure could be completely disappeared.The conductivity of Al-Mg-Si-Zr alloy was better than that of Al-Mg-Si-Ce alloy at ageing 2~24 h/180℃.During the aging time,the conductivity of Al-Mg-Si-Zr alloy increased from 53.07%IACS to 60.63%IACS,while that of Al-Mg-Si-Zr alloy only increased from 53.23%IACS to 58%IACS.The microstructures of two alloys were observed by transmission electron microscopy(TEM).It was found that Zr promoted the precipitation ofβ"(Mg5Si6),and formed Al3Zr precipitation phase.The precipitation of these two phases greatly reduced the electron scattering in the alloy and thus improved the conductivity of Al-Mg-Si-Zr alloy.