Observations and simulations for phase separation process of immiscible Fe50Sn50 alloy droplets placed on a chilling surface
Observations and simulations for phase separation process of immiscible Fe50Sn50 alloy droplets placed on a chilling surface
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DOI：
10.1016/j.jallcom.2023.169565
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发表时间：
2023-03
影响因子：
6.2
通讯作者：
Yuhao Wu;Jingwen Su;Li Zhang;Mingchen Du
中科院分区：
文献类型：
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作者：
Yuhao Wu;Jingwen Su;Li Zhang;Mingchen Du
通过电弧熔炼实验和格子Boltzmann模拟研究了非混溶Fe50Sn50合金液滴在激冷表面的液相分离和组织演变机制。相分离形貌的模式选择强烈依赖于样品的直径。随着样品尺寸的减小，相分离时间缩短，两层宏观偏析形态首先转变为中间相分离形态，最后转变为均匀分散的显微组织。离样品底部越远，相分离时间越长，富锡相越大。建立了分析水冷铜型结晶器表面Fe50Sn50合金液滴温度场特性的传热方程。理论分析表明，样品是从底部向顶部逐渐冷却的。在弧形熔化样品的顶部和底部之间存在较高的温度梯度，达到每毫米几百开尔文，这导致了极强的Marangoni对流的发生。样品尺寸越小，温度梯度越大，两层宏观偏析结构中富铁区偏离样品底部的程度越大。模拟得到的两层相分离形态与实验观测结果吻合较好。数值模拟表明，Marangoni对流对相分离的影响明显强于Stokes运动，密度较大的富铁球倾向于向上移动，形成偏离样品底部的富铁区。
Liquid phase separation and microstructure evolution mechanisms of immiscible Fe50Sn50alloy droplets placed on a chilling surface have been investigated by both arc melting experiments and lattice-Boltzmann simulations. The pattern selection of phase-separated morphologies strongly depended on the sample diameter. With the reduction in sample size, phase separation time was shortened, two-layer macrosegregation morphologies first transformed into intermediate phase-separated morphologies and finally changed into a homogeneously dispersed microstructure. The farther away from the sample bottom the longer the phase separation time and the larger the Sn-rich phase. A heat transfer equation was proposed to analyze the temperature field characteristics of Fe50Sn50alloy droplets placed on the surface of a water-cooled copper mold. Theoretical analyses revealed that the sample gradually cooled from the bottom to the top of the sample. There existed a relatively high temperature gradient of several hundred Kelvins per millimeter between the top and the bottom of the arc melted sample, which induced the occurrence of an extremely intense Marangoni convection. The smaller the sample size the larger the temperature gradient and the greater deviation-degree of Fe-rich zone in two-layer macrosegregation structure from the bottom of the sample. The simulated two-layer phase-separated morphology agreed well with the experimental observations. Numerical simulations demonstrated that the effect of Marangoni convection on the phase separation was significantly stronger than the Stokes motion, and Fe-rich globules with a larger density tended to move upward to form a Fe-rich zone deviating from the bottom of the sample.