CHANGEMENTS DE PHASES ET MICROSTRUCTURES
J. Phys. IV France 04 (1994) C3-41-C3-46
Relations entre dilatation et premiers stades de l'oxydation interneL. CHARRIN, A. COMBE, A. CHARAI, F. CABANE and J. CABANE
Laboratoire de Métallurgie, EDIFIS, URA 443 du CNRS, Faculté des Sciences et Techniques de Saint Jérôme, case 511, 13397 Marseille cedex 20, France
Variation of the lattice parameter during interna1 oxidation of dilute Ag(Mg) alloys is closely related to the successive steps of the oxidation process at low temperature. Models of elementary reactions are proposed by taking into account a potential barrier due to the strain field near the reacting species. First, substoichiometric species ([O]/[Mg]<1) form in a non expanded zone ; then excess oxygen by comparison with the amount necessary to form stoichiometric MgO oxide and over stoichiometric clusters are responsible of the highly expanded zone observed. The decrease of deformation and of excess oxygen which occurs at last is related to an evolution toward more compact clusters.
© EDP Sciences 1994