本文系统地研究了8090Al-Li合金的微观结构与力学性能的关系。结果表明,合金性能的变化主要归因干δ′颗粒尺寸的变化和S′相的析出。δ′相容易析出并迅速长大,而S′相析出的孕育期较长,时效前冷变形可促进S′相析出。δ′相和S′相共同析出可改善合金强度和塑性,其最佳时效条件为190℃,20—30h。另外,在有平衡相析出的高角晶界容易形成无沉淀区,在峰值时效条件,其宽度可达200nm以上,但在亚晶界难以形成。
The change of mechanical properties of the 8090 Al-Li alloy influenced by aging is attributed to the change of δ′phase particle size and the precipitation of S′phase. The δ′phase may easily precipitate and rapidly grow, but the S′phase can only precipitate with a longer stage of incubation. The S′phase precipitation would be promoted by cold work prior to aging. The co-precipitation of δ′and S′phases could improve the strength and plasicity of the alloy, for which aging at 190℃ for 20-30 h seems to be optimal. In addition, the precipitate free zone (PFZ) can form at high angle grain boundary and its width is over 200 nm at peak aging condition.But at sub-grain boundary, the formation of PFZ is difficult.
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