A Solid-Liquid Diffusion Couple Study of a Peritectic Reaction in Iron-Carbon System

δ-iron and melted high carbon steel with carbon contents of the solvus and liquidus lines, respectively, in an iron-carbon equilibrium phase diagram, were held in contact with each other at 1696 K. The thickness of the γ-phase formed between the δ-phase and the liquid phase was measured. The relationship between the thickness x (μm) and the holding time t (s) was found to be x=85.7 t0.50. The distribution of the carbon concentration over those three phases was also measured. The results showed a steep gradient of the carbon concentration in the γ-phase and an equilibrium conjugation relationship at both the δ/γ and γ/liquid interfaces. These findings regarding the growth rate of the γ-phase and the distribution of the carbon concentration were both in good agreement with the results of a simulation of the peritectic reaction based on a diffusion-controlled mechanism.