2015

Penttilä, Sami; Betova, Iva; Bojinov, Martin; Kinnunen, Petri; Toivonen, Aki

In the present paper, the kinetic and transport parameters of inner and outer layer growth on two ODS (Oxide Dispersion Strengthened) alloys, PM2000 and MA956, is presented. Parameters are estimated using an upgraded model that assumes that the growth of the outer layer is governed by the transport of cations through the inner layer via an interstitialcy mechanism. The updated model is able to reproduce accurately the depth profiles of individual constituent elements in the inner and outer layers, as well as in the diffusion/transition layer of the alloy situated between the inner layer and the bulk substrate. As a result of the calculations, kinetic and transport parameters of inner and outer layer growth are estimated for oxidation times from 600 to 2000 h at 650 °C. The main conclusion that can be drawn from the calculations is that the most of the rate constants and also the diffusion coefficients tend to decrease with time of oxidation at a constant temperature.