A new non-isothermal pre-aging treatment was proposed and utilized in Al-Mg-Si-Cu-Zn alloys, together with natural aging and artificial aging. The influence of cooling rates on subsequent precipitation behaviors was investigated by experimental and thermodynamic simulations. The results show that by controlling the formation of clusters/GP zones through changing pre-aging cooling rates, i.e. PA-0.2, PA-0.3 and PA-0.4 (°C/min, from 80 °C to 40 °C), an excellent bake hardening increment and natural aging stability can be obtained. The highest bake hardening increment can reach 180 MPa for PA-0.4 sample, which is twice higher than those of Al-Mg-Si-(Cu) alloys. The microhardness remains almost unchanged within NA for 14 days at a lower level of approximately 85 HV_0.2. Thermodynamic simulations estimate the solvus temperatures and chemical composition for GP zones, revealing the strengthening and stabilising mechanisms behind: a) Mg-Zn- clusters formed during pre-aging can suppress Mg-Si- clusters formation in the natural aging process, b) non-isothermal hinders the precipitates growth, a faster cooling rate leads to smaller and softer Mg-Zn- clusters, and c) the formation of a heterogeneous microstructure contributes to the high bake-hardening response without changing the type of strengthening phase β″. Finally, the clustering and aging process was illustrated and explained.

提出了一种新的非等温预时效处理方法，并将其与自然时效和人工时效一起用于Al-Mg-Si-Cu-Zn合金。通过实验和热力学模拟研究了冷却速率对后续降水行为的影响。结果表明，通过改变预时效冷却速率，即 PA-0.2、PA-0.3 和 PA-0.4（°C/min，从 80°C 到 40°C）来控制簇/GP 区的形成，可获得优异的烘烤硬化增量和自然时效稳定性。PA-0.4样品的最高烘烤硬化增量可达180 MPa，是Al-Mg-Si-(Cu)合金的两倍。_{显微硬度在大约 85 HV 0.2}的较低水平下 14 天在 NA 内几乎保持不变. 热力学模拟估计了 GP 区的固溶线温度和化学成分，揭示了其背后的强化和稳定机制：a) 预时效过程中形成的 Mg-Zn- 簇可以抑制自然时效过程中 Mg-Si- 簇的形成，b) 非-等温阻碍了析出物的生长，更快的冷却速度导致更小和更软的 Mg-Zn-团簇，并且 c) 异质微观结构的形成有助于高烘烤硬化响应而不改变强化相 β" 的类型。最后，对聚类和老化过程进行了说明和解释。