Abstract In the present study, nanoscale precipitation and phase growth in Mg-15Gd(wt%) binary alloy are comprehensively studied by atomic-resolution high angle annular dark field - scanning transmission electron microscopy (HAADF-STEM). Various nanoscale precipitate structures, including βH, β′, βT′, βM and β′′-like structure, assembled by the “basic unit” as building block, are observed, reconstructed and discussed in detail. In the early stage of precipitation, the precipitate growth basically follows y (nm) = 1.53x − 2.68 (nm) and protrusions start to grow when the size of a precipitate reaches a threshold value. Long-range diffusion of Gd solute preferentially proceeds along 10 1 ¯ 0 >Mg directions and protrusions are formed. A large number of fine β′ precipitates exist and act as the key strengthening structures. The formation of precipitate-free zones in the over-age condition is attributed to the intertwining of precipitates.

中文翻译：

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Mg-Gd 二元合金中的纳米级析出和相生长：使用 HAADF-STEM 进行原子级研究

摘要 本研究采用原子分辨率高角度环形暗场-扫描透射电子显微镜(HAADF-STEM)综合研究了Mg-15Gd(wt%)二元合金的纳米级析出和相生长。各种纳米级沉淀结构，包括βH、β'、βT'、βM和β''类结构，由“基本单元”作为积木组装而成，被观察、重建和详细讨论。在沉淀的早期阶段，沉淀物的生长基本上遵循 y (nm) = 1.53x - 2.68 (nm)，当沉淀物的尺寸达到阈值时，突起开始生长。Gd 溶质的长程扩散优先沿 10 1 ¯ 0 >Mg 方向进行，并形成突起。大量细小的β'析出物存在并作为关键的强化结构。