Correlations Between the Structure, Energy and Diffusivity of Grain and Interphase Boundaries

The paper illustrates the benefits of a combined use of computer simulations of interfacial properties and experiments performed on macroscopic, well-defined bicrystals. The results from two studies are reported. Relative energies of inclined Cu Σ3 grain boundaries were determined by thermal grooving experiments on diffusion-bonded Cu bicrystals. A comparison with calculated energies for crystallographically identical interfaces points to the possibility of macrofaceting of inclined grain boundaries upon annealing. Grain boundary entropy effects are discussed as another possible reason for small differences between theory and experiment. The diffusion rate of Ag* radiotracer in heterophase boundaries of diffusion-bonded Ag-Cu bicrystals can qualitatively be correlated with computed structural details of crystallographically identical Ag-Cu and Ag-Ni phase boundaries. The (computed) site-to-site variation of vacancy formation enthalpy on the (110) phase boundary leads to an anisotropy of Ag* phase boundary diffusion.