A phase-field study has been conducted to obtain an understanding of the formation mechanism of the script lamellar pattern of MoSi2/Mo5Si3 eutectic composite, which is a promising candidate for high-temperature structural application. The spacing of the lamellar pattern in the simulation results shows good agreement with that of experimental observations and analytical solutions under three growth rates: 10 mm/h, 50 mm/h, and 100 mm/h. The discontinuity of Mo5Si3 rods, in contrast to the regular eutectic with a continuous pattern, is claimed to be caused by the instability of the solid-liquid interface. In this study, the implementation of Mo5Si3 nucleation over the solid-liquid interface has been proposed and successfully reproduced the characteristic of discontinuity. A highly random and intersected lamellar pattern similar to that observed in the ternary MoSi2/Mo5Si3 eutectic alloyed with 0.1at% Co has been obtained in simulation owing to the increase in the frequency of nucleation. In addition, it has been demonstrated that the inclination of the Mo5Si3 rod can be reproduced by taking into account the strong relaxation of lattice strain energy, which is generally considered to be negligible in eutectic reaction, as the result of the formation of ledge-terrace structure.

中文翻译：

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定向凝固MoSi2/Mo5Si3共晶的相场模拟形成机制

已经进行了相场研究，以了解 MoSi2/Mo5Si3 共晶复合材料的脚本层状图案的形成机制，这是高温结构应用的一个有希望的候选者。模拟结果中层状图案的间距与实验观察和解析解的间距在三种生长速率下显示出良好的一致性：10 mm/h、50 mm/h 和 100 mm/h。与具有连续图案的规则共晶相比，Mo5Si3 棒的不连续性据称是由固液界面的不稳定性引起的。在这项研究中，提出了在固-液界面上实施 Mo5Si3 成核并成功再现了不连续性的特征。由于成核频率的增加，在模拟中获得了类似于在与 0.1at% Co 合金化的三元 MoSi2/Mo5Si3 共晶中观察到的高度随机和交叉的层状图案。此外，已经证明可以通过考虑晶格应变能的强弛豫来重现 Mo5Si3 棒的倾斜度，这通常被认为在共晶反应中可以忽略不计，这是形成壁台的结果结构体。