8. Atomistic Simulations of Metal–Al₂O₃ Interfaces

Interfaces between metals and ceramics are of great importance for a wide range of industrial applications such as multifunctional devices, fuel cells, thermal barrier coatings, corrosion protection, and microelectronics. The technological interest arises from the possibility to obtain composite materials with much better characteristics than that of both constituents. In order to control the metal–ceramic interfaces it is necessary to understand them at different scale levels. The approaches used for this goal can be ranged from models at the macroscale to first principles calculations. Atomistic theoretical studies of varied metal–ceramic systems are based on ab initio calculations or molecular dynamics simulations which allow to understand the interactions at the interface at the atomic level. Using the plane wave pseudopotential method within density functional theory, the electronic and mechanical properties of Me–Al₂O₃ interfaces with fcc (Ni, Cu, Pd, Ag, Pt, Au) and bcc (Nb, Mo, Ta, W) metals are investigated to find correlations between the work of separation and crystal structure, strain conditions, and electronic properties of both constituents. Stress–displacement relationships of separation perpendicular to the interface are calculated in case of Al, Cu, Ag, and Nb on the Al-terminated Al₂O₃(0001) surface. It is shown that obtained results such as work of separation and tensile strength can be understood from the electronic structure. The influence of misfit dislocations on the fracture behavior of an Al–Al₂O₃ interface is demonstrated using classical molecular dynamics simulations. The comparison with experimental data provides good agreement for both the work of separation and qualitative prediction of mechanical reinforcement.