A Finite Difference Model Describing Carburization in High-Temperature Alloys

A finite difference model describing the diffusion of carbon in high-temperature alloys and its chemical reaction with the alloy components that lead to carbide precipitation was set up previously. It has been extended here to treat the formation of up to three different chromium carbides (Cr3C2, Cr7C3, and Cr23C6). Carbon diffusion profiles that had been obtained experimentally were recalculated by the model. Kinetic and thermodynamic input data, such as the diffusion coefficient of carbon and the solubility products of all three carbides, could be fitted systematically. This resulted in (1) excellent agreement between the calculated and measured profiles and (2) the determination of an unequivocal set of the input data necessary for the model calculations.