Size-dependent diffusion controls natural aging in aluminium alloys
Size-dependent diffusion controls natural aging in aluminium alloys
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DOI：
10.1038/s41467-019-12762-w
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发表时间：
2019-10-18
影响因子：
16.6
通讯作者：
Pogatscher, Stefan
中科院分区：
文献类型：
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作者：
Dumitraschkewitz, Phillip;Uggowitzer, Peter J.;Pogatscher, Stefan
材料科学中的一个关键问题是性能发展的速度有多快，这与相变的动力学有关。在金属中，动力学主要与扩散有关，对于替代元素，扩散通过移动的原子晶格空位实现。事实上，结构变化往往需要非平衡空缺。各种重要合金（例如Al合金或Mg合金）的快速淬火导致例如自然老化，即材料中溶质原子的轻微移动，这显著改变了材料性质。在这项研究中，我们证明了自然时效的尺寸效应，在AlMgSi合金通过原子探针断层扫描与近原子图像分辨率。我们发现，非平衡空位扩散过程一般停止时，样品尺寸达到纳米尺度。这就排除了低于一定尺寸的样品的聚集和自然老化，并对通过显微镜技术研究非平衡扩散和微观结构变化产生影响。
A key question in materials science is how fast properties evolve, which relates to the kinetics of phase transformations. In metals, kinetics is primarily connected to diffusion, which for substitutional elements is enabled via mobile atomic-lattice vacancies. In fact, non-equilibrium vacancies are often required for structural changes. Rapid quenching of various important alloys, such as Al- or Mg-alloys, results for example in natural aging, i.e. slight movements of solute atoms in the material, which significantly alter the material properties. In this study we demonstrate a size effect of natural aging in an AlMgSi alloy via atom probe tomography with near-atomic image resolution. We show that non-equilibrium vacancy diffusional processes are generally stopped when the sample size reaches the nanometer scale. This precludes clustering and natural aging in samples below a certain size and has implications towards the study of non-equilibrium diffusion and microstructural changes via microscopy techniques.