Atomic scale observations of the chemical composition of a metal/ceramic interface

A combined transmission electron microscopy, HREM and atom probe field ion microscopy (APFIM) study of a Cu/MgO heterophase interface produced by internal oxidation of a Cu(Mg) alloy is presented. It is demonstrated that by combining these three microscopies it is possible to determine the chemical identity of the terminating plane on the oxide side of a Cu/MgO (111)-type interface directly without any deconvolution of the experimental data. In particular, it is demonstrated that the bonding across the (111) interface, in a common < 111 > direction, has the sequence Cu|O|Mg|... and not Cu|Mg|O|... via APFIM measurements of the highly localized chemistry.