Transformation character of ferrite formation by a ledge mechanism under a mixed-control model

• Published in: International journal of minerals, metallurgy and materials metallurgy and materials, 2012-05, Vol.19 (5), p.428-433
• Main Authors: Liu, Zhen-qing, Yang, Zhi-gang, Li, Zhao-dong, Zhang, Chi
• Format: Article
• Language: English
• Subjects: Austenite; Carbon; Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Composites; Corrosion and Coatings; Diffusion; Fe-C合金; Ferrite; Ferrous alloys; Glass; Ledges; Materials Science; Mathematical models; Metallic Materials; Natural Materials; Supersaturation; Surfaces and Interfaces; Thin Films; Transformation temperature; Transformations; Tribology; Two dimensional models; 字符; 控制模型; 机制; 混合; 窗台; 迁移扩散; 铁素体
• ISSN: 1674-4799; 1869-103X
• DOI: 10.1007/s12613-012-0574-6

A mixed-control model was developed to study the transformation character of ferrite formation by a ledge mechanism. A nu- merical two-dimensional diffusion-field model was combined to describe the evolution of the diffusion field ahead of the migrating austenite/ferrite interface. The calculation results show that the bulk diffusion-controlled model leads to a deviation from experimental results under large solute supersaturation. In the mixed-control model, solute supersaturation and a parameter Z together determine the transformation character, which is quantified by the normalized concentration of carbon in austenite at the austenite/ferfite interface. By comparing with experimental data, thepre-exponential factor of interface mobility, M0, is estimated within the range from 0.10 to 0.60 mol-m·J^-1·s^-1 for the alloys with 0.1 lwt%-0.49wt% C at 700-740℃. For a certain Fe-C alloy, the trend of the transformation character relies on the magnitude of M0 as the transformation temperature decreases.