Experimental studies on Si mobilities in the Fe3Si/Fe–3%Si alloy diffusion couples and the mathematical simulation by DICTRA

Abstract

The microstructure and electromagnetic properties of electrical steel can be greatly influenced by silicon, making it essential to understand the diffusion behaviors of silicon in Fe–Si alloys. In our work, diffusion couples of Fe₃Si/Fe–Si alloys were made and diffusion treatments for different durations were carried out. Concentration distributions of Fe and Si in the diffusion couples were detected by using an electron probe microanalyzer (EPMA). Based on the diffusion theory and the thermodynamic data of the Fe–Si alloy systems, the interdiffusion kinetic behavior of the solid diffusion couples of Fe–Si alloys were simulated using the diffusion-controlled transformation (DICTRA) software, revealing close alignment between the predicted and observed Si concentration distributions. On this basis, the diffusion coefficients, diffusion activation energies, and finger front factors were calculated based on the measured data and compared with the measured diffusion parameters for body-centered cubic (BCC) structured Fe–Si alloys. Transmission electron microscopy (TEM) was used to analyze and elucidate the mechanism responsible for the relatively low diffusion activation energy of Si measured with the diffusion couples.