Misfit accommodation at the Cu(1 1 1)/α-Al2O3(0 0 0 1) interface studied by atomistic simulation

In frame of an atomistic model we study the misfit accommodation at the Cu(1 1 1)/α-Al2O3(0 0 0 1) interface with the orientation relation 〈1̄ 0 1〉Cu∥〈1 1̄ 0 0〉Al2O3. We use the well-known interatomic potentials for bulk Cu and sapphire and we make an attempt to describe interaction across the interface by simple pair potentials with a few fitting parameters. We also introduce a measure of coherency sensitive to the atomic relaxations near the interface. Misfit dislocation networks, the change of coherency near the interface due to atomic relaxations, and the interface energy calculated for different magnitudes of the potential fitting parameters are compared. The results are rather sensitive to the interatomic potentials used for copper. Morse pairwise potential gives a low energy of the stacking fault and the misfit dislocations dissociate in partials. A more realistic many-body potential results in a higher energy of the stacking fault and dislocation dissociation is suppressed. Moreover, the misfit dislocation network found with the Morse potential is unstable when interaction across the interface is rather strong. The instability effect disappears in frame of the many-body potential which, unlike the Morse potential, reproduces the elastic moduli and the anisotropic constant of copper.