Zur Bildung von Ag2S-Kristallen an Ag/Ni-Phasengrenzen

On the surface of Ag/Ni-composite materials, the positions offering the best conditions for enrichment and nucleation become decorated with Ag 2 S-crystals. Such positions may be phase boundaries between the nickel and the silver, or surface defects such as scratches, grain- and sub-grain boundaries in the silver. Decoration occurs more quickly and with greater density the higher is the sulphur content of the nickel. The atmosphere in which the ageing takes place (laboratory air and desiccator) appears to have no discernable effect on the process. The formation of Ag 2 S-crystals on the silver surfaces after longer periods of ageing is explained by the surface diffusion of sulphur and its reaction with the silver causing pitting of the silver surface