Microstructural evolution of aluminium–copper alloys during the downward directional solidification process
Microstructural evolution of aluminium–copper alloys during the downward directional solidification process
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DOI：
10.3139/146.111005
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发表时间：
2014-02
影响因子：
0.8
通讯作者：
Fu Wang;D. Ma;Jun Zhang;Lin Liu;Jianping Hong;S. Bogner;A. Bührig-Polaczek
中科院分区：
文献类型：
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作者：
Fu Wang;D. Ma;Jun Zhang;Lin Liu;Jianping Hong;S. Bogner;A. Bührig-Polaczek
摘要研究了Al-Cu合金在向下定向凝固过程中的组织演变规律。在平面到细胞的转变点，平面的液体/固体（L/S）界面在中心破裂。这与液态金属冷却过程中的行为形成对比，在液态金属冷却过程中，界面在外围破裂。此时的临界抽取速率高于理论值。除此之外，对于Al-2.0 wt.%的合金，在恒定GL下，一次枝晶臂间距（λ1）作为拔出速率（V）的函数的变化也被研究。铜合金的制备工艺符合常规工艺。将我们实验中的λ1与Kurz-Fisher、Ma和Trivedi模型计算值λ1进行比较，表明这些模型计算的λ1高估了我们的实验结果。然而，由Hunt模型计算的λ1与λ1的实验值吻合得很好。当我们将样品的直径从13 mm减小到9 mm并保持其他参数不变时，L/S界面保持平面形状。这表明，在较小的样品中，L/S界面比在较大的样品中更稳定。这一结果与液态金属冷却过程中的结果进行了对比。
Abstract The microstructural evolution of Al–Cu alloys during the downward directional solidification process was investigated. At the planar-to-cellular transformation point, the planar liquid/solid (L/S) interface broke down at the centre. This was contrasted with the behaviour in the liquid metal cooling process, where the interface broke down at the periphery. The critical withdrawal rate at this point was higher than the theoretical value. In addition to this, the variation in the primary dendrite arm spacing (λ1) as a function of the withdrawal rate (V) at constant GL for the Al-2.0 wt.% Cu alloy agreed with the conventional processes. The comparison of λ1 in our experiment to the calculated value λ1 using the Kurz–Fisher, Ma and Trivedi models showed that λ1, calculated by these models, overvalued our experimental results. However, the λ1 calculated from the Hunt model agreed well with the experimental values of λ1. When we reduced the diameter of the sample from 13 mm to 9 mm and maintained the other parameters constant, the L/S interface retained a planar shape. This indicated that the L/S interface was more stable in the smaller sample than that in the larger. This result contrasted with the result in the liquid metal cooling process.