Experimental and computational study of diffusion mobilities for the bcc phase in the Fe-Al-(Si, Mn) systems

The electrical steel has attracted considerable attention due to the excellent soft magnetic properties, which can be improved by the addition of alloying elements such as Al, Si and Mn. To increase element contents, the hot-dipping and diffusion-annealing method has been developed. The method requires detailed insight on the diffusion behavior of the alloy system. In the present work, the re-assessment of the diffusion mobilities for the bcc phase (including both bcc_A2 and bcc_B2 phases) in the Fe-Al system were firstly performed based on the critical evaluation of the available experimental data. By applying the diffusion-couple method, the interdiffusion coefficients in bcc_A2 Fe-Al-Si alloys were determined and used to optimize the diffusion mobilities. The bcc_A2 Fe-Al-Mn diffusion couples were also designed to verify the diffusion mobilities. Comparison between the model-predicted and experimental diffusion data such as diffusion coefficients, concentration profiles and diffusion paths confirms the reliability of the present mobility parameters.