Phase-field simulation of abnormal anisotropic grain growth in polycrystalline ceramic fibers
Phase-field simulation of abnormal anisotropic grain growth in polycrystalline ceramic fibers
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DOI：
10.1016/j.commatsci.2020.109926
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发表时间：
2020-12
影响因子：
3.3
通讯作者：
J. Kundin;Renato S. M. Almeida;Hesham Salama;Hedieh Farhandi;K. Tushtev;K. Rezwan
中科院分区：
文献类型：
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作者：
J. Kundin;Renato S. M. Almeida;Hesham Salama;Hedieh Farhandi;K. Tushtev;K. Rezwan
本工作提出了一种相场方法来真实地模拟温度高于1000 °C时多晶陶瓷纤维中的异常晶粒生长。在这些条件下，晶粒生长的特征在于在正常晶粒的基质中形成大的细长矩形晶粒。多相场模型扩展的机制，负责异常各向异性生长：各向异性界面能，各向异性界面迁移率和再结晶驱动力。两种类型的迁移率各向异性被认为是：各向异性由于晶粒之间的取向差和各向异性由于依赖于倾角。利用该模型对Nextel 610陶瓷纤维在1200-1300 °C不同停留时间下的热处理实验数据进行了检验。不同时刻的实验结果与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组织。在大多数模型情况下，异常颗粒具有矩形形状，与实验相似。实验晶粒尺寸分布和晶粒形状的最佳拟合是通过模拟实现的界面迁移率的取向差依赖。此外，它示出，在实验中观察到的随时间的晶粒生长速率的强烈下降，可以通过考虑到晶界上的杂质的偏析，导致晶界迁移率降低的模拟再现。
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.