ENERGETIC AND KINETIC ASPECTS OF THE FACETING TRANSFORMATION OF A SIGMA-3-GRAIN BOUNDARY IN CU

Grain boundary facets forming at the intersection between grain bounda ry and free surface in diffusion bonded Cu SIGMA3 bicrystals during pr olonged annealing have been characterized crystallographically by meta llographic methods. The facet geometry is discussed with regard to the relevant [011] section of the inverse gamma(b)-Plot for SIGMA3 grain boundaries which is constructed from earlier computer simulation data on SIGMA3 grain boundary energies gamma(b). It is shown that the obser ved faceting reduces the total grain boundary energy by 15-20%. A face ting mechanism is proposed which is consistent with the experimentally observed facet geometry and with the atomistic structure of the facet s.