John Ågren

KTH, Stockholm, Sweden

Modelling diffusion during precipitate growth in concentrated multicomponent alloys

When modelling precipitation processes in concentrated multicomponent alloys, e.g. steels and high-entropy alloys, one would like to account for high supersaturation and cross-diffusion effects. In principle this could be achieved with phase-field method but a detailed numerical solution of the set of transport equations is very costly allowing only a very limited number of particles to be treated in a multicomponent system. In practice one would rather like to predict the evolution of a size distribution of particles often of different phases, e.g. carbides and intermetallics. It is then common to apply the Kampmann-Wagner approach and it is necessary to represent the diffusional fluxes by simple analytical expressions. This is the topic of the present lecture. A method based on balancing the dissipation due to the irreversible processes with the available thermodynamic driving force is then useful. In literature this is often referred to as the Onsager thermodynamic extremum principle.