4D synchrotron X-ray tomographic quantification of the transition from cellular to dendrite growth during directional solidification
4D synchrotron X-ray tomographic quantification of the transition from cellular to dendrite growth during directional solidification
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DOI：
10.1016/j.actamat.2016.07.002
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发表时间：
2016-09-15
期刊：
影响因子：
9.4
通讯作者：
Lee, P. D.
中科院分区：
文献类型：
--
作者：
Cai, B.;Wang, J.;Lee, P. D.
凝固形态直接影响材料的力学性能，因此人们建立了许多枝晶组织形态演变的模型。然而，定向凝固模型的验证数据很少，特别是对金属合金的直接观察，无论是胞晶组织还是枝晶组织。在这项研究中，我们进行了四维同步辐射X射线层析成像(三个空间方向加时间)，以研究在温度梯度阶段从胞状到柱状树枝晶形态的转变以及随后柱状树枝晶的生长。细胞形态高度复杂，有频繁的侧桥。随着形态不稳定的开始，从细胞前线生长出来的突起被捕捉到，以及随后这些突起发展成已建立的树突。还捕捉到了影响凝固组织的其他机制，包括枝晶断裂/夹断，并将定量结果与所提出的机制进行了比较。结果表明，4D成像可以提供新的数据来解释和验证凝固模型。(C)2016 Acta Materialia Inc.，由Elsevier Ltd.出版。这是CC许可下的一篇开放获取文章。
Solidification morphology directly impacts the mechanical properties of materials; hence many models of the morphological evolution of dendritic structures have been formulated. However, there is a paucity of validation data for directional solidification models, especially the direct observations of metallic alloys, both for cellular and dendritic structures. In this study, we performed 4D synchrotron X-ray tomographic imaging (three spatial directions plus time), to study the transition from cellular to a columnar dendritic morphology and the subsequent growth of columnar dendrite in a temperature gradient stage. The cellular morphology was found to be highly complex, with frequent lateral bridging. Protrusions growing out of the cellular front with the onset of morphological instabilities were captured, together with the subsequent development of these protrusions into established dendrites. Other mechanisms affecting the solidification microstructure, including dendrite fragmentation/pinch-off were also captured and the quantitative results were compared to proposed mechanisms. The results demonstrate that 4D imaging can provide new data to both inform and validate solidification models. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. This is an open access article under the CC BY license.