ENERGY AND STRUCTURE OF INTERPHASE BOUNDARIES

The energy of interphase boundaries between noble metals (Au, Cu) and various ionic crystals (LiF, NaCl, KCl, MgO, Al2O3, mica) was investigated by means of the plate/sphere method. The results obtained suggest that the coincidence model is not applicable to describe the structure of interphase boundaries of low energy between noble metals and ionic crystals. The atomic structure of the low energy boundaries observed may be understood in terms of the proposed "lock-in model". Moreover the energy of interphase boundaries seems to be strongly dependant on the temperature. Measurements of the energy of Cu/MgO and Au/Al2O3 interphase boundaries at 550°C and 950°C indicate the existence of a transition from an energetically anisotropic boundary structure into an isotropic one

PRESSURE EFFECT ON PREMELTING TRANSITION IN A TILT GRAIN BOUNDARY IN AN Fe-Si ALLOY

The effect of pressure on the diffusion of zinc along a 43° tilt grain boundary in an Fe-6at%Si alloy was investigated. Zinc penetrated into the grain boundary from a 100 µm thick liquid layer on the surface of the bicrystal. It was found that penetration of zinc causes a premelting phase transition in the grain boundary. The phase transition was suppressed for pressures higher than 0,5 GPa