COMPUTER-SIMULATION OF DIFFUSION IN MULTIPHASE SYSTEMS

A general model to treat multicomponent diffusion in multiphase disper sions is presented. The model is based on multicomponent diffusion dat a and basic thermodynamic data and contains no adjustable parameters. No restriction is placed on the number of components or phases that ta ke part in the calculations, as long as the necessary thermodynamic an d kinetic data are available. The new model is implemented into the DI CTRA software, which makes use of THERMO-CALC to handle the thermodyna mics. The model is applied to carburization of Ni alloys and heat trea tment of welded joints between dissimilar materials. In both cases, th e diffusion is accompanied by carbide formation or dissolution. A good agreement between experiments and calculations is found, despite the fact that no adjustable parameters are needed.