Diffusion-coefficient measurements in liquid metallic alloys
Diffusion-coefficient measurements in liquid metallic alloys
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DOI：
10.1007/s11663-004-0085-6
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
Je-Hyun Lee;Sha Liu;Hirofumi Miyahara;R. Trivedi;R. Trivedi
中科院分区：
文献类型：
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作者：
Je-Hyun Lee;Sha Liu;Hirofumi Miyahara;R. Trivedi;R. Trivedi
液体中扩散系数(Dl)的值通常是通过测量淬火平面界面前的成分分布来获得的。实验结果显示出明显的散射性。这种分散的主要原因将被证明是由于液体中流体流动的存在。在Al-Cu系中进行了定向凝固研究，首次确定了扩散生长所需的实验条件。然后测量成分分布，以获得从4.0到24.0wtptCu的Dlfor合金成分的值。沿液相线测得d1=2.4×10−3mm2/S，这一结果明显小于文献报道的值(3.0~5.5×10−3mm2/S).结果表明，这些值的散布与所用样品的直径有关，从而与实验中的流体流量有关.文中概述了获得和验证扩散生长条件的详细实验程序，并讨论了对数据的适当分析。
The value of the diffusion coefficient in the liquid (Dl) is generally obtained from the measurement of composition profiles ahead of a quenched planar interface. The experimental results show significant scatter. The main reason for this scatter will be shown to be due to the presence of fluid flow in the liquid. Directional-solidification studies in the Al-Cu system have been carried out to first establish the experimental conditions required for diffusive growth. The composition profiles are then measured to obtain the values of Dlfor alloy compositions ranging from 4.0 to 24.0 wt pct Cu. The value ofDl=2.4×10−3mm2/s was obtained along the liquidus line, and this result is significantly smaller than the values reported in the literature, which vary from 3.0 to 5.5 × 10−3mm2/s. It is shown that the scatter in the reported values can be correlated with the diameter of the sample used and, thus, with the fluid flow present in their experiments. Detailed experimental procedures to obtain and verify diffusive-growth conditions are outlined, and appropriate analyses of the data are discussed.