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基于Three Dimensional Atom Probe(3DAP)以及First-Principles对Al-Si-Cu-Mg合金中团簇及后续沉淀的演变过程进行了研究。3DAP试验表明,Al-1.0Si-1.5Cu-0.5Mg合金时效0.25h后基体中主要存在点状的Si-Si团簇、Si-Mg团簇、Si-Mg-Cu团簇,与第一性原理计算所表明的以上各结构中溶质原子间结合较强的结果相符,同时由于大量Si原子的扩散聚集,导致Si-Cu团簇结构出现;时效0.25~2h后基体中Si、Mg、Cu原子继续聚集,点状的Si-Si、Si-Cu、Si-Mg团簇长大并向针状的Si-Mg-Cu团簇演变;时效2~4h后,Si、Mg、Cu原子继续聚集,促进针状Si-Mg-Cu结构长大的同时,部分大尺寸的Si-Mg-Cu结构逐渐向板条状的Q′相转变,同时富Cu结构出现。
The evolution of clusters and subsequent precipitation in Al-Si-Cu-Mg alloys was investigated based on Three Dimensional Atom Probe (3DAP) and First-Principles. The results of 3DAP showed that there were mainly Si-Si clusters, Si-Mg clusters and Si-Mg-Cu clusters in Al-1.0Si-1.5Cu-0.5Mg alloy after aging for 0.25h, The calculated results show that the solute atoms strongly bond with each other. At the same time, the Si-Cu clusters appear due to the diffusion and aggregation of a large number of Si atoms. After aging for 0.25-2 h, Si, Mg and Cu atoms The Si-Si, Si-Cu and Si-Mg clusters grow up and grow into needle-like Si-Mg-Cu clusters. After aging for 2-4h, the Si, Mg and Cu atoms continue to aggregate, While promoting the growth of acicular Si-Mg-Cu structure, part of the large-size Si-Mg-Cu structure gradually transforms into lath-like Q ’phase and Cu-rich structure appears at the same time.