Double-atomic-wall-based dynamic precipitates of the early-stage S-phase in AlCuMg alloys
Double-atomic-wall-based dynamic precipitates of the early-stage S-phase in AlCuMg alloys
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DOI：
10.1016/j.actamat.2012.08.023
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发表时间：
2012-11
期刊：
影响因子：
9.4
通讯作者：
S. B. Wang;Jianghua Chen;M. Yin;Z. R. Liu;D. Yuan;J. Liu;C. Liu;C. Wu
中科院分区：
文献类型：
--
作者：
S. B. Wang;Jianghua Chen;M. Yin;Z. R. Liu;D. Yuan;J. Liu;C. Liu;C. Wu
高强度铝合金的发展一直面临着一个难题：由于其尺寸小，早期强化相的成分、结构和演变难以表征。即使对于广泛使用的AlCuMg合金（Wilm在世纪前首次发现了金属中的沉淀硬化现象），基本问题仍然存在：对于最有效的强化沉淀物（称为S相）存在多少种不同的前体，以及它们如何转变为S相？在这里，我们采用原子分辨率电子显微镜成像和第一性原理能量计算来解决这些问题。我们的研究表明，早期阶段的S相沉淀物是高度动态的成分和结构。这些动态析出相具有自己的双Cu-Mg原子壁来引导它们的演化，它们随着热时效的进行按照三条演化路径开始、成熟和长大，导致无一例外地形成具有偶数Cu-Mg原子层的S相析出相。
Developments of high-strength aluminum alloys have always faced a difficult problem: owing to their small size, the early-stage strengthening precipitates are difficult to characterize in terms of composition, structure and evolution. Even for the widely used AlCuMg alloys, in which the phenomenon of precipitation hardening in metals was first discovered by Wilm more than a century ago, the essential questions remain: how many different precursors exist for the most effective strengthening precipitates (referred to S-phase), and how do they transform to the S-phase? Here we employ atomic-resolution electron microscopy imaging and first-principles energy calculations to address these problems. Our study demonstrates that the early-stage S-phase precipitates are highly dynamic in both composition and structure. Having their own genetic double Cu–Mg atomic walls to guide their evolution, these dynamic precipitates initiate, mature and grow with thermal aging following three evolution paths, leading to the S-phase precipitates formed, without exception, with even numbers of Cu–Mg atomic layers.