The recrystallization behavior of cold-rolled Al–Zn–Mg–Cu-based alloy sheets was systematically investigated by varying the Cu and Mg contents. With increasing Cu and Mg contents, the recrystallized grain size was reduced from 54.9 to 23.3 \(\upmu\)m owing to the reduced ratio of the size to volume fraction of microscale particles. Interestingly, the sensitivity of different particles to particle-stimulated nucleation (PSN), which is reflected by the linear experimental coefficient (k), was dependent on their morphologies and relative fractions. The k value was considerably small (0.07) in the Cu-free alloys, implying that the Zn and Mg containing particles have an insignificant effect on the PSN. However, the k value increased significantly to 0.61 with the increase in Cu content to 1.3 wt%, because the rod-shaped Al₇Cu₂Fe particles formed a large plastic deformation zone around them. The addition of 2.0 wt% Mg led to the increase in the relative fraction of round-shaped Al₂CuMg particles, increasing the k value from 0.46 to 0.86. The Al₇Cu₂Fe particles were a stronger source of PSN than the Al₂CuMg particles, forming more recrystallized grains. Although Mg addition could increase the yield strength of the aged sheets, a strength–ductility trade-off arose. However, the addition of Cu simultaneously increased the yield strength and elongation because the uniform distribution of grain boundary precipitates caused by grain refinement could reduce the stress concentration during plastic deformation.

Graphical Abstract

中文翻译：

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Cu和Mg含量对Al-Zn-Mg-Cu基合金薄板再结晶行为的影响

通过改变 Cu 和 Mg 的含量，系统地研究了冷轧 Al-Zn-Mg-Cu 基合金板的再结晶行为。随着 Cu 和 Mg 含量的增加，再结晶晶粒尺寸从 54.9 减小到 23.3  \(\upmu\) m，这是由于微米级颗粒的尺寸与体积分数之比降低。有趣的是，由线性实验系数 ( k )反映的不同粒子对粒子刺激成核 (PSN) 的敏感性取决于它们的形态和相对分数。无铜合金中的k值相当小（0.07），这意味着含 Zn 和 Mg 的颗粒对 PSN 的影响不显着。然而，k随着Cu含量增加到1.3 wt％，该值显着增加到0.61，因为棒状Al ₇ Cu ₂ Fe颗粒在它们周围形成了大的塑性变形区。添加 2.0 wt% Mg 导致圆形 Al ₂ CuMg 颗粒的相对分数增加，k值从 0.46 增加到 0.86。Al ₇ Cu ₂ Fe 颗粒是比 Al _{2更强的 PSN 来源}CuMg 颗粒，形成更多的再结晶晶粒。虽然添加镁可以提高老化板的屈服强度，但出现了强度-延展性权衡。然而，Cu的添加同时提高了屈服强度和延伸率，因为晶粒细化引起的晶界析出物的均匀分布可以降低塑性变形过程中的应力集中。

图形概要