STUDY OF COPPER PRECIPITATES IN ALPHA-IRON BY COMPUTER-SIMULATION .1.INTERATOMIC POTENTIALS AND PROPERTIES OF FE AND CU

Pair potentials describing Fe-Fe and Cu-Cu interatomic interactions ba sed on the generalized pseudopotential theory are presented. Different properties of pure Fe and Cu such as elastic constants, phonon disper sion curves, vacancy formation and migration energy, interstitial form ation energy, thermal expansion, stacking fault energy, pressure-volum e dependence and relative stability of the bcc, fee and hcp structures were studied using these potentials. They are in good agreement with the experimental results. The phase transformations fcc --> bcc in iro n 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.