Abstract The present work proposes a phase-field approach to realistically simulate abnormal grain growth in polycrystalline ceramic fibers at temperatures above 1000 °C. Under these conditions, grain growth is characterized by the formation of large elongated rectangular grains in a matrix of normal grains. The multi-phase-field model is extended by mechanisms which are responsible for the abnormal anisotropic growth: anisotropic interface energy, anisotropic interface mobility and a recrystallization driving force. Two types of the mobility anisotropy are considered: anisotropy due to the misorientation between grains and anisotropy due to the dependency on inclination angles. The experimental data from heat treatments of the ceramic fiber Nextel 610 at 1200–1300 °C with different dwell times are examined by the proposed model. The comparison of the experiment and the simulation results at various times shows that the extended multi-phase-field model is able to simulate the microstructure realistically. In most model cases, abnormal grains have a rectangular shape, similar to the experiment. The best fit of the experimental grain size distribution and the grain shape is achieved by the simulation with the misotientation dependency of the interface mobility. Furthermore, it was shown that a strong decrease on the grain growth rate with time, observed in the experiment, can be reproduced by the simulations taking into account the segregation of impurities on grain boundaries that results in the decreasing grain boundary mobility.

中文翻译：

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多晶陶瓷纤维异常各向异性晶粒生长的相场模拟

摘要 目前的工作提出了一种相场方法来真实地模拟 1000 °C 以上温度下多晶陶瓷纤维中的异常晶粒生长。在这些条件下，晶粒生长的特征是在正常晶粒的基体中形成大的细长矩形晶粒。多相场模型通过负责异常各向异性生长的机制进行扩展：各向异性界面能、各向异性界面迁移率和再结晶驱动力。考虑了两种类型的迁移率各向异性：由于晶粒之间的错误取向导致的各向异性和由于倾斜角的依赖性导致的各向异性。所提出的模型检查了陶瓷纤维 Nextel 610 在 1200-1300 °C 下不同停留时间的热处理实验数据。实验与不同时间模拟结果的对比表明，扩展的多相场模型能够真实地模拟微观结构。在大多数模型情况下，异常颗粒具有矩形形状，类似于实验。实验晶粒尺寸分布和晶粒形状的最佳拟合是通过具有界面迁移率的错误取向依赖性的模拟来实现的。此外，还表明，在实验中观察到的晶粒生长速率随时间的强烈下降，可以通过模拟再现，同时考虑到晶界上杂质的偏析导致晶界迁移率降低。