Growth kinetics of zinc-iron diffusion layer in galvanized zinc 30CrMnSi

The galvanized zinc 30CrMnSi was annealed at different temperatures for different time, the diffusion kinetics of zinc and the laws of microstructural evolution at different holding temperatures were studied by means of SEM and EPMA. The results show that intermediate phases appear in the order of ℒ, δ, Γ phase; when the holding temperature is above 300℃, the growth of intermetallic compounds in zinc-iron diffusion layer is controlled by diffusion rate, thickening as a parabolic growth, and when the holding temperature is below 300℃, the diffusion rate of zinc is very low, and the growth of intermetallic compounds is determined mainly by interface reaction rate and the thickening shows an approach linear growth behavior. The growth activation energy for the growth of the compound is 162.37 kJ/mol. The growth kinetics model is obtained, by which the thickness of the diffusion layer can be evaluated at experimental temperature.