Precipitation strengthening in Cu-Ni-Si alloys modeled with ab initio based interatomic potentials

Effective interaction potentials suitable for Cu/δ-Ni₂Si and Cu/β-Ni₃Si are developed. We optimise the potential parameters of an embedded atom method potential to reproduce forces, energies, and stresses obtained from ab initio calculations. Details of the potential generation are given, and its validation is demonstrated. The potentials are used in molecular dynamics simulations of shear tests to study the interactions of edge dislocations with coherent δ-Ni₂Si and β-Ni₃Si precipitates embedded in a copper matrix. In spite of significantly different crystallographic structures of copper and δ-Ni₂Si which usually result in circumvention of dislocations, we also observed cutting processes in our simulations. Dislocations cut for a specific orientation of the δ-Ni₂Si precipitate and in some cases where dislocation loops originating from previous circumvention processes are present in the glide plane. It is found that β-Ni₃Si precipitates have a similar effect on precipitation strengthening as δ-Ni₂Si. Dislocations usually cut β-Ni₃Si but increased coherency strain can lead to circumvention processes.