For most of Al–Mg–Si-(Cu) alloys and their composites, artificial aging hardening can be impaired by precedent natural aging. In this study, a pre-aging treatment before natural aging was adopted to improve the hardness of the artificially aged SiCp/6092Al composite and 6092Al alloy. Effects of the multi-step aging treatment, including pre-aging, natural aging and final artificial aging, on microstructures and mechanical properties were investigated by the hardness test, conductivity test, differential scanning calorimetry and transmission electron microscopy. It was shown that pre-aging exhibited a more obvious improvement in the final hardness in the composite, compared to that in the 6092Al alloy. The supersaturated solute atoms formed clusters during natural aging after pre-aging, but the clustering behaviors were different between the composite and 6092Al alloy, leading to the different pre-aging hardening effects. In the composite, it was easy for supersaturated solute atoms to participate into pre-aging clusters during natural aging. As pre-aging clusters could transform into precipitates during artificial aging, precipitate sizes were not affected by natural aging. In contrast, in the 6092Al alloy, it was easy for supersaturated solute atoms to form new clusters during natural aging after pre-aging. As it was difficult for these new clusters to transform into precipitates during artificial aging, precipitates were enlarged with prolonged natural aging time. Because the clustering behaviors during natural aging after pre-aging showed different effects on precipitation, the hardness after artificial aging did not change with prolonged natural aging time in the composite but decreased in the 6092Al alloy.

对于大多数的Al-Mg-Si-（Cu）合金及其复合材料，先验的自然时效会削弱人工时效硬化。在这项研究中，采用自然时效前的预时效处理来提高人工时效SiCp / 6092Al复合材料和6092Al合金的硬度。通过硬度测试，电导率测试，差示扫描量热法和透射电子显微镜研究了包括预老化，自然老化和最终人工老化在内的多步老化处理对组织和力学性能的影响。结果表明，与6092Al合金相比，预时效对复合材料的最终硬度有更明显的改善。过饱和的溶质原子在自然老化后会形成簇，但复合材料与6092Al合金的团聚行为不同，导致了不同的时效硬化效果。在复合材料中，过饱和溶质原子很容易在自然老化过程中参与预老化团簇。由于预老化团簇在人工老化过程中可能转变为沉淀物，因此沉淀物的大小不受自然老化的影响。相反，在6092Al合金中，过时效后的自然时效过程中，过饱和的溶质原子很容易形成新的团簇。由于这些新团簇在人工老化过程中很难转化为沉淀物，因此随着自然老化时间的延长，沉淀物会增大。由于预老化后自然老化过程中的聚集行为对降水有不同的影响，