Kinetics of the displacement reaction between Fe and Cu2O at temperatures between 800 and 1050°C

The products of the displacement reaction between solid iron and Cu₂O in the temperature range of 800 to 1050°C are solid copper, wustite and magnetite. The product oxide in contact with the iron phase is in the form of rods embedded in a matrix of copper. A thin layer of copper separates the oxide rods from the Cu₂O phase. The rates of growth of the product phases are controlled by solid-state counterdiffusion of oxygen and iron through the product phases, except for the initial stage of the reaction. A previously developed kinetic model for the diffusion-controlled growth of the product phases is employed to calculate the rates of growth of each of the product phases. Theoretical values of growth rates are in excellent agreement with experimental values for temperatures above 950°C. Below 950°C, the mechanism for the growth of the magnetite phase changes, which yields marked differences between the experimental and theoretical rates of growth. The mechanism for the displacement reaction below 950°C has not been determined.