A lattice Monte Carlo analysis on chemical reaction with moving boundary

Abstract

The current paper aims to simulate combined mass diffusion and chemical reaction. Two solid reactants are brought into contact and the product is formed at the interface. Chemical reaction is assumed to occur instantaneously, thus the reaction rate is limited only by the interdiffusion of the two solid constituents. First, parametric studies for a range of constant diffusivities are performed and simple relations for the growth of the product phase are obtained. It is found that the thickness of the product layer increases proportionally to the square root of the product of diffusivity and time. In the second part of the analyses the formation of NiAl by interdiffusion of nickel and aluminum is simulated. This self-propagating exothermic reaction is of great interest for joining temperature-sensitive components. Within the limits of these calculations, the concentration dependence of the diffusion coefficients of nickel and aluminum is considered in order to improve the accuracy of the simulation.