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 boundary and free surface in diffusion bonded Cu SIGMA3 bicrystals during prolonged annealing have been characterized crystallographically by metallographic 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 observed faceting reduces the total grain boundary energy by 15-20%. A faceting mechanism is proposed which is consistent with the experimentally observed facet geometry and with the atomistic structure of the facets.