The quantitative effects of pre-treatments, namely pre-stretching and natural ageing (NA), on the precipitation sequence, precipitation kinetics and mechanical properties of an Al–Cu–Li–Mg–Ag alloy during artificial ageing were systematically investigated, aiming to elucidate the mechanisms by which these effects proceed. At the early ageing stage, pre-stretching could inhibit the formation of GP zones by restricting the Mg–Cu co-clustering, and could result in a higher nucleation rate of the T₁ precipitates due to an increase in the quantity of dislocations covered by solute segregations. The introduction of NA after pre-stretching could further increase the number density of T₁ by providing more nucleation sites, which evolved from the much more Mg–Ag co-clusters forming during the NA process. With prolonging ageing time, the precipitation kinetics for T₁ were strongly enhanced by pre-stretching due to a more efficient nucleation of T₁ and a more rapid growth rate of this phase, which was attributed to the combination of the suppression effect on the GP zone precipitation and the pipe diffusion effect derived from the introduced dislocations. When applying NA after pre-stretching, a further acceleration of the precipitation kinetics was observed, which was related to the formation of much more T₁ nuclei. At the peak-aged condition, both the two pre-treatments could not only refine the precipitates but also result in a higher T₁ volume fraction. Mechanisms of the strength changes induced by the pre-treatments under various ageing conditions were discussed in detail in view of these experimental results.

系统研究了预处理（即预拉伸和自然时效（NA））对人工时效过程中Al-Cu-Li-Mg-Ag合金的析出顺序，析出动力学和力学性能的定量影响，旨在阐明产生这些影响的机制。在早期时效阶段，预拉伸可以通过限制Mg-Cu共聚而抑制GP区的形成，并且由于位错的覆盖增加了T ₁析出物的成核速率。溶质偏析。预拉伸后引入NA可以进一步增加T ₁的数密度通过提供更多的成核位点，这些成核位点是由NA过程中形成的更多的Mg-Ag共聚簇形成的。随着老化时间的延长，由于更有效的T ₁成核作用和该相的更快生长速率，预拉伸大大增强了T ₁的沉淀动力学，这归因于对GP的抑制作用的结合。区域位错和管道扩散效应源自引入的位错。在预拉伸后使用NA时，观察到沉淀动力学进一步加速，这与更多T ₁核的形成有关。在峰值时效条件下，两种预处理不仅可以提纯沉淀物，而且还可以提高T₁体积分数。鉴于这些实验结果，详细讨论了在各种时效条件下预处理引起的强度变化的机理。