Modelling of spinodal decomposition in the binary Fe-Cr system

Abstract: Spinodal decomposition is a phenomenon which hinders the usage of ferrite containing steels under certain conditions. With a better understanding and knowledge of spinodal decomposition new ferritic and duplex stainless steels could be designed. The project is divided into two parts, an experimental part and a theoretical part. The aim of the theoretical part was to compare simulated values of the amplitude and wavelength of spinodal decomposition, obtained from solving the Cahn-Hilliard equation with other experimental values. The experimental part is performed as to determine the chemical diffusion coefficient and the mobility of Fe and Cr in the binary Fe-Cr system for lower temperatures using the Boltzmann-Matano method from chemical profiles of different samples. Another purpose with the project is to determine if the methods and the approach which are taken is viable and useful for calculating diffusion coefficients and if it can be used in studies to come. The simulations were in good agreement with other data at higher time intervals, but deviates at lower times. The calculated interdiffusion coefficients were in all cases lower than the expected values and as such the conclusion that is drawn is that the methods which are used could need further development.