Theoretical investigation of the influence of reaction and diffusion kinetics upon thin-film reactive diffusion

Atomistic kinetic Monte Carlo simulations, considering the thermodynamic model of the nonregular solid solution on a rigid fcc lattice and using the first-neighbor atomic pair interaction Ising model, were performed to investigate the influence of reaction and diffusion kinetics on thin-film reactive diffusion with a semi-infinite substrate. The simulations show that compound bulk energies have no effect on the phase sequence of appearance during sequential phase formation. However, a diffusion asymmetry between the elements composing the solid solution has a strong effect on sequential phase formation. Diffusion asymmetry increases the critical thickness of the simultaneous-to-sequential phase formation transition, modifies the phase formation sequence, and controls which phase is the first to form. Asymmetrical diffusion can promote transient phase formation and can prevent some phases of the bulk phase diagram from forming. In addition, it influences the thicknesses of phases and their lifetimes during thin-film reactive diffusion. Consequently, the control of atom diffusion during reactive diffusion, for example, thanks to the controlled introduction of impurities, should allow the phase formation sequence of a given binary system to be modified.