Vacancy segregation at surface grain boundaries and their intersection:: an atomistic study

The vacancy formation energy is calculated with an N-body interatomic potential for copper at different interfaces - the (001) surface and the Sigma =5 (310) < 001 > tilt grain boundary - and at the emergence of this grain boundary at the (001) surface. The formation energy at the surface and for some sites of the grain boundary is about half of the formation energy in the bulk, E-vac.bulk(for), whereas it can be as low as 0.1 E-vac.bulk(for) at the emergence of the grain boundary at the surface. These results are discussed along the main driving forces evidenced for the chemical interfacial segregation.