DETERMINATION OF BOUNDARY ENERGIES OF Cu FROM THE SHAPE OF BOUNDARY SiO₂ PARTICLES

Abstract
The boundary energies of symmetric [011] tilt and [011] and [001] twist boundaries of Cu were measured by a new method : SiO₂ particles were introduced on grain boundaries by internally oxidizing bicrystals of Cu-0.06%Si. The boundary energies in terms of the Cu-SiO₂ interfacial energy were determined from the lenticular shapes of boundary SiO₂ particles observed by transmission electron microscopy. Besides the energy cusps reported previously for FCC metals, several new cusps were clearly resolved by the present method : Σ27, 11, 33 and 57 for [011] twist and Σ41 and 29 for [001] twist boundaries. The relative boundary energy was found to depend sensitively on the partial pressure of oxygen, as-oxidized or degassed. That is, oxygen segregates on boundaries, affecting the boundary energies.