微量元素La,Ti及均匀化处理对纯铝导电性能的影响

Effect of trace elements La, Ti and homogenization on electrical properties of pure aluminum

摘要:

在本文中,通过熔炼制备Al-La, Al-Ti及 Al-La-Ti 合金研究了La、Ti微量元素添加对纯铝的导电性和强度的影响。同时研究了在500 ℃下均匀化处理8 h之后样品的导电性能与微观结构的变化。结果表明,当La添加量不超过0.3%时,Al-La合金的导电率会保持在较高的值60.35% IACS左右,因为La与铝中的杂质Si,Fe反应析出。随着Ti元素添加量的增加,Al-Ti合金的强度明显增加,这主要是Ti原子的固溶强化的作用。当同时在纯铝中添加La和Ti元素时,会使合金在Al-La合金的基础上强度得到提升,导电率有所下降,但是导电率仍然高于单独添加Ti元素时的Al-Ti合金。这主要是因为La与Ti之间相互反应生成Ti₂Al₂₀La化合物并且析出,有利于导电性的提升。研究结果表明,均匀化处理对样品微观结构变化的影响很小,而导电性的提高主要是因为均匀化处理消除了铸态样品的大部分显微疏松,缩孔和显微针孔等铸造缺陷。

Abstract:

In this paper, Al-La, Al-Ti and Al-La-Ti alloys were prepared to study the influence of Ti and La on the electrical conductivity and strength of alloys. The electrical properties, strength and microstructure evolution of alloys before and after homogenization treatment at 500 ℃ for 8 h were investigated. The results show that the electrical conductivity of Al-La can keep a high level as 60.35% IACS when the content of La does not exceed 0.3% due to the precipitation of the compounds containing La, Si and Fe. The tensile strength of Al-Ti alloy was enhanced rapidly with the increasing addition of Ti due to the increasing content of Ti atoms in Al matrix. When La and Ti were added simultaneously, the strength of alloys was higher than that of Al-La alloys, and the electrical conductivity was decreased compared with that of Al-La alloys but was higher than that of Al-Ti samples, which is mainly attributed to the formation of the new secondary phase Ti₂Al₂₀La. Homogenization treatment had little impact on microstructure of alloys but reduced the number of casting defects so that increased the electrical conductivity of all samples.