Fe-C-Mn三元合金中奧氏體-鐵素體相變的相場模擬Fe-C-Mn三元合金中奧氏體-鐵素體相變的相場模擬PHASE-FIELD MODELING OF γ→α TRANSFORMATION IN FE-C-MN TERNARY ALLOYS 采用相場法研究了Fe-C-Mn三元合金在臨界區等溫過程中發生的奧氏體-鐵素體相變. 基于Gibbs自由能平衡理論，相場模型考慮了替換性元素Mn在奧氏體/鐵素體相界面內擴散所導致的自由能耗散，因此本模型可描述Fe-C-Mn三元合金中因Mn在相界面偏聚所導致的相變停滯和相變不完全現象. 利用相場模型進一步研究了不同Mn含量對奧氏體-鐵素體相變微觀組織轉變和相變動力學的影響. 結果顯示：隨著Mn含量的增加，鐵素體相的轉變速率和最終體積分數降低，Mn在奧氏體/鐵素體相界面內擴散所導致的溶質拖曳現象越明顯，相變不完全的轉變程度加劇. The effect of Mn element on the austenite-to-ferrite transformation has been widely discussed in terms of physical models and experiments due to its technological importance for alloy design in steel industries. In recent years, focus of this issue is placed on the effect of alloying element on the migrating interface. In this context, a multi-phase-field model coupled with a Gibbs-energy dissipation model due to Mn diffusion inside the austenite/ferrite interface was developed to simulate the isothermal austenite-to-ferrite transformation in ternary Fe-C-Mn alloys. This model can make a clear description of the mixed-mode nature of the transformation in ternary Fe-C-Mn alloys. Compared with the simulation results under the condition of no energy dissipation of Mn diffusion, the transformation kinetics and final ferrite faction are found to be reduced, and the distinctions between them are analyzed by the evolution of Gibbs-energy dissipation at the moving interface. In order to investigate the effect of different Mn contents on structural morphology and kinetics, three different alloys have been employed. It is found that the difference of growth rate between ferrite growth along and perpendicular to austenite boundary increases with increasing Mn concentration, leading to the change of ferrite morphology from elliptical to flat. Both the transformation kinetics and the volume fraction of ferrite are reduced, and the degree of incomplete transformation intensifies with increasing Mn concentration, while a higher Mn concentration has a stronger reducing effect on driving force of moving interface. 全文下載：http://pan.baidu.com/s/1hrFGhi0
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