Influence of gravity level on Columnar-to-Equiaxed Transition during directional solidification of Al-20 wt.% Cu alloys
Influence of gravity level on Columnar-to-Equiaxed Transition during directional solidification of Al-20 wt.% Cu alloys
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DOI：
10.1016/j.actamat.2016.03.007
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发表时间：
2016-05-15
期刊：
影响因子：
9.4
通讯作者：
Nguyen-Thi, H.
中科院分区：
文献类型：
--
作者：
Abou-Khalil, L.;Salloum-Abou-Jaoude, G.;Nguyen-Thi, H.
在地球上和两次抛物线飞行期间对精炼和非精炼Al-Cu合金进行了凝固实验，以研究重力水平对凝固动力学的影响。采用基于微焦点X射线源的X射线照相装置，对微结构的形成进行了原位和实时监测。本文首次对金属合金在不同重力水平下的定向凝固过程进行了直接观测。通过实验对比研究，揭示了重力对破碎和枝晶碎片输运的影响。此外，当重力水平急剧增加时，揭示了从柱状组织到完全等轴组织的壮观转变。结果表明，这一现象是一个突然增加的液体过冷度的柱状前锋伴随着静水压力的变化的结果。(C)2016 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
Solidification experiments on refined and non-refined Al-Cu alloys were carried out on Earth and during two parabolic flights to investigate the influence of gravity level upon solidification dynamics. In situ and real-time monitoring of the microstructure formation was characterized by using an X-ray radiography device based on a microfocus X-ray source. This paper presents for the first time direct observation of metal alloy directional solidification under varying gravity level. By a comparative study between the experiments, the influence of gravity on fragmentation and dendrite fragments transport was enlightened. In addition, a spectacular transition from a columnar to a fully equiaxed microstructure was revealed when there is a sharp increase of gravity level. It was shown that this phenomenon is a consequence of a sudden increase of the liquid undercooling ahead of the columnar front accompanying the change in hydrostatic pressure. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.