Mechanism of internal oxidation in silver alloys

The internal oxidation mechanism in silver alloys was studied by residual resistivity, gravimetric, and calorimetric measurements, and by transmission electron microscopy. If the flux, of oxygen atoms is very large with respect to the oxide formation, the mechanism of internal oxidation includes two stages. The first one is the fixation of oxygen in the form of oxidized elementary species, including only one solute atom. These species are stable and keep a certain mobility. The second one is the coalescence process of these elementary species with the formation of the first clusters. When the flux of oxygen atoms is slowed down, the oxide formation mechanisms are more complicated. The initially formed species can include more than one solute atom because of their diffusion. The two stages are not separate.