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用正交设计试验方案,研究了2091AL-Li 合金的分级时效工艺,优选出了一种能够同时改善合金强度和塑性的热处理工艺。并通过示差扫描热分析、TEM 和 SEM 观察等,探讨了分级时效改善合金性能的机制。结果表明,该合金经100 C 成核处理后形成 GPB 区,可作为第二阶段时效时S′相的异质形核点,促使 S′相在晶内弥散析出。从而有效地分散δ′,相引起的共面滑移。成核处理还缩短了第二级时效时达到峰时效状态所需的时间,减弱了晶界无析出带的形成倾向,有利于改善合金的强度与塑性。
The orthogonal experimental design was used to study the grading aging process of 2091AL-Li alloy. A heat treatment process was proposed to improve the strength and ductility of the alloy simultaneously. The mechanism of grading aging to improve the properties of the alloy was discussed by differential scanning calorimetry, TEM and SEM. The results show that GPB zone can be formed after 100 C nucleation treatment, which can be used as heterogeneous nucleation sites of S ’phase during the second stage of aging. Thereby effectively dispersing the δ ’, phase-induced co-planar slip. The nucleation treatment also shortens the time required to reach the peak-aged state at the second stage of aging, weakens the formation tendency of the precipitate-free zone in the grain boundary, and improves the strength and plasticity of the alloy.