Understanding phenomena of inter-diffusion of atoms in surface and interface alloying is of great importance in thin-film growth of bimetallic compounds. Recent studies show that interface mixing behavior of systems may be depends on several factors, such as misfit strain, crystallographic plane of substrate, and thickness of overlayer. In this regards, we use molecular static and Monte Carlo simulation to determine mixing energetic and concentration profile at interface for systems contain one and two monolayers of adatom adsorbed on (100) FCC crystal surface interact with Lennard- Jones potential in temperature near 0 K. For systems with one monolayer of adatom, intermixing becomes more energetically preferable as increasing magnitude of potential well-depth. For systems with two monolayers of adatom, complex evolution of concentration profile is observed along with increasing magnitude of potential well-depth and atomic size mismatch. We relate this behavior to the interplay between contribution of bond substitution effect and contribution of initial and final stress to minimize total energy of systems along with interchange between substrate atoms and adatoms.