OXIDATION OF ALUMINA FORMING MATERIALS

摘要

FeCrAl alloys strengthened by yttria oxide dispersions (ODS alloys) are now well-developed, though questions still exist concerning their oxidation mechanism and life time. The association of original and complementary techniques, microscopic observations at different scales (SEM and TEM), various analyses (EDX, EPMA), kinetic studies and oxygen exchange tests with SIMS profiling, and especially deflection experiments originally used as a kinetic tool, allowed to obtain new informations a bout the oxidation mechanisms of such a lloys. So, it was possible to relate the diffusion phenomena in the oxide film and in the substrate to the effect of the oxygen pressure and to deduce the chemical life time associated to the aluminium depletion in the substrate. Also, the γ → α alumina transformation was studied according to the oxygen pressure and its kinetics was determined using the deflection technique, in association with transmission electron microscopy on cross sectional thin foils.