STUDY OF COPPER PRECIPITATES IN ALPHA-IRON BY COMPUTER-SIMULATION .2.INTERATOMIC POTENTIAL FOR FE-CU INTERACTIONS AND PROPERTIES OF COHERENT PRECIPITATES

A pair potential describing Fe-Cu interactions has been constructed. T he potential was fitted to the vacancy-Cu binding energy in bcc Fe and the dilatation properties of coherent Cu precipitates. Properties of Cu-point defects complexes in the bcc-Fe matrix and point defect-preci pitate interactions were calculated. The binding energy of a Cu atom w ith a small coherent precipitate (up to 180 Cu atoms) was estimated as a function of the precipitate size. This was found to be a non-monoto nic function for small precipitates. Dilatation and structural propert ies of coherent precipitates were studied and the relaxation of the ma trix around precipitates was found. The vacancy-precipitate interactio n energy and vacancy migration near and within precipitates were also studied. It was found that the anisotropy of vacancy migration and int eraction correlates with the anisotropy of the relaxation of the matri x atoms around the precipitate.