Decomposition of the metastable phase in the silver-germanium system

Abstract

The decomposition behaviour of the metastable h.c.p. phase in a splatcooled silver-23 at. % germanium alloy was studied by differential thermal analysis, X-ray and electron metallographic techniques. A two-stage decomposition process was observed. The activation energies for the two stages were found to be 0·91±0·09 eV/atom and 1·95±0·19 eV/atom, respectively. The first stage is associated with the transformation from h.c.p. to metastable f.c.c. solid solution, the second stage represents the precipitation of germanium from this solid solution. The total enthalpy of transformation was found to be 2·21±0·22 meV/atom.