2099铝锂合金均匀化退火的微观组织及 Al3Zr 析出分析

摘要

研究2099铝锂合金铸态及均匀化处理后的微观组织和成分分布以及该合金最佳均匀化处理状态时 Al3Zr的析出情况。结果表明：2099铝锂合金铸态的微观组织存在严重的枝晶偏析，很多低熔点共晶相分布在晶界，合金中 Cu 和 Mg 元素在晶界分布不均匀；经过一系列不同温度和时间的均匀化处理后，2099铝锂合金铸态微观组织中的非平衡相逐渐溶解，各元素分布趋于均匀；2099铝锂合金的过烧温度为515℃，最佳的均匀化制度为505℃/24 h；经该制度均匀化处理后，Al2CuMg、Al2CuLi 和 AlLi 相大部分回溶进α(Al)基体中，通过透射电镜可观察到 Al3Zr 析出相以及α(Al)基体的超点阵结构；并且该均匀化制度与均匀化动力学方程得到的结论基本一致。%The microstructure and composition distribution of as-cast and homogenized 2099 aluminum-lithium alloy were studied, and Al3Zr precipitate was observed in the best homogenized situation. The results show that severe dendrite segregation exists in the microstructure of 2099 aluminum-lithium alloy ingot, furthermore the grain boundary has many eutectic phases with low melting-point, and the nonuniform distribution of Cu and Mg elements is obvious in grain boundary of the alloy. The non-equilibrium eutectic phases dissolve when homogenized at a series of different temperatures and times, the grain boundary becomes sparse and all elements become more homogenized. The over-burnt temperature of 2099 aluminum-lithium alloy is 515 ℃, and the optimum homogenizing process is 505 ℃/24 h. When the alloy is treated with the best homogenizing process, the Al2CuMg, Al2CuLi, and AlLi phases are mostly re-dissolute to the α(Al) base, and the Al3Zr precipitates and α(Al) superlattice are observed as well. And the optimum homogenizing process is agreed with the conclusions from the homogenizing kinetic equation.