Study of copper precipitates in α-iron by computer simulation I. Interatomic potentials and properties of Fe and Cu

Pair potentials describing Fe-Fe and Cu-Cu interatomic interactions based on the generalized pseudopotential theory are presented. Different properties of pure Fe and Cu such as elastic constants, phonon dispersion curves, vacancy formation and migration energy, interstitial formation energy, thermal expansion, stacking fault energy, pressure-volume dependence and relative stability of the bcc, fcc and hcp structures were studied using these potentials. They are in good agreement with the experimental results. The phase transformations fcc → bcc in iron and bcc → fcc in copper have been simulated by molecular dynamics. It was found that the transformation in iron mainly follows the Bain distortion, while that in copper follows the Burgers type mechanisms.