Interatomic potential for copper–antimony in dilute solid–solution alloys and application to single crystal dislocation nucleation

A new interatomic potential for copper–antimony (Cu–Sb) in low Sb concentration solid–solution alloys is proposed based upon the Lennard-Jones (LJ) pair formulation. Parameters for this new potential, σ and ε, are motivated by calculations of the Cu–Sb heat of solution (heat of mixing) and the strain field generated by a single substitutional impurity in single crystal copper, which is analyzed for impurity (dopant) atoms with various atomic radii. A well established embedded-atom method (EAM) potential is used to model the host copper. The ε parameter is derived for a range of values of σ by matching to the experimental value of the heat of solution. Then, the strain field around a single dopant atom is computed for each set of the calculated LJ parameters. Ultimately, the final parameters for the Cu–Sb interaction are selected to match the strain field corresponding to the atomic radius mismatch between Sb and Cu and are compared with the Eshelby solutions which are based on classical theory of elasticity. As an application of this new potential, it is shown using molecular dynamics simulations that the plastic deformation behavior of single crystal copper is affected by the characteristics of the strain field around the dopant atoms.