Phase-Field Simulation of Austenite to Ferrite Transformation and Widmanstätten Ferrite Formation in Fe-C Alloy
Phase-Field Simulation of Austenite to Ferrite Transformation and Widmanstätten Ferrite Formation in Fe-C Alloy
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DOI：
10.2320/matertrans.47.2725
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发表时间：
2006-11
影响因子：
1.2
通讯作者：
A. Yamanaka;T. Takaki;Y. Tomita
中科院分区：
文献类型：
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作者：
A. Yamanaka;T. Takaki;Y. Tomita
采用相场法模拟了Fe-C合金等温奥氏体向铁素体转变过程中魏氏铁素体片的形成过程。采用正则化梯度能量系数法研究了界面性质的各向异性对魏氏铁素体板生长动力学的影响。结果表明，采用该方法可以模拟出非常尖锐的板尖，并且魏氏铁素体板的形貌与实验观察到的形貌吻合得很好。对单个魏氏铁素体板生长的模拟结果表明，随着各向异性强度的增加，魏氏铁素体板的伸长速率增加，导致尖端界面能增加。此外，魏氏组织铁素体的形态变化的晶界他异形铁素体进行了模拟。结果表明，从他形铁素体生长魏氏铁素体片需要高的界面能各向异性。在生长初期，由于形态的不稳定性，直接形成于他异形铁素体凸部的板尖可以优先发展为魏氏铁素体板。魏氏铁素体片的分布取决于晶界他异形铁素体的初始界面形状。
The formation process of Widmanstatten ferrite plates during the isothermal austenite to ferrite transformation in Fe-C alloy is simulated by the phase-field method. The effects of the anisotropy of interfacial properties on the growth kinetics of Widmanstatten ferrite plates are investigated by the regularized gradient energy coefficient method, which enables us to introduce a wide range of interface anisotropy. It is found that by employing this method, a very sharp tip of the plate can be simulated and the morphology of Widmanstatten ferrite plate is in good agreement with the experimentally observed one. The simulation results of the growth of a single Widmanstatten ferrite plate suggest that the lengthening rate of the Widmanstatten ferrite plate increases with increasing strength of anisotropy, which causes the increase of interfacial energy at the tip. Furthermore, the simulations of the morphological changes of Widmanstatten ferrite from a grain boundary allotriomorph ferrite are performed. The results clarify that the growth of Widmanstatten ferrite plates from allotriomorph ferrite requires high anisotropy of interfacial energy. It is also proved that, in the early stage of the growth, the plate tips directly formed at the convex part of allotriomorph ferrite can preferentially develop into Widmanstatten ferrite plates due to the morphological instability. The distribution of Widmanstatten ferrite plates depends on the initial interface shape of the grain boundary allotriomorph ferrite.