Abstract Based on Cs-corrected scanning transmission electron microscopy (STEM), the present paper reports on the precipitation evolution in Mg-Gd-Ag alloy aged at 200 °C. Basal γ″ precipitates serve as the key strengthening structures in the under-aged sample. The formation of γ″ involves the displacement of a (0 0 0 1) layer along 1 1 2 ¯ 0 Mg , as proved by HAADF observations from both 1 1 2 ¯ 0 Mg and 1 0 1 ¯ 0 Mg . Under the peak-age condition, the alloy is strengthened by basal γ″ and prismatic β ′ . At the over-age stage, coarse particles, which are enriched with Ag and Gd, and highly stacked γ″ form within the alloy. No γ′ is observed through the ageing of this Mg-Gd-Ag alloy.

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关于 Mg-Gd-Ag 合金中强化析出物结构：使用 Cs 校正 STEM 的原子分辨率研究

摘要 基于Cs 校正扫描透射电子显微镜(STEM)，本文报道了Mg-Gd-Ag 合金在200 °C 时效时的析出演化。基底γ″析出物是欠时效样品中的关键强化结构。γ″的形成涉及沿 1 1 2 ¯ 0 Mg 的 (0 0 0 1) 层位移，HAADF 对 1 1 2 ¯ 0 Mg 和 1 0 1 ¯ 0 Mg 的观测证明了这一点。在峰值时效条件下，合金通过基体γ''和棱柱β'强化。在过时效阶段，合金内部形成富含Ag和Gd的粗颗粒和高度堆积的γ″。在这种 Mg-Gd-Ag 合金的老化过程中没有观察到 γ'。