Berlin 2005 – wissenschaftliches Programm

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M: Metallphysik

M 40: Diffusion I

M 40.1: Vortrag

Dienstag, 8. März 2005, 10:30–10:45, TU H2038

Simulation of Internal Oxidation of Engineering Alloys under Industrial Process Conditions — •Jürgen Gegner — SKF GmbH, Material Physics, Ernst-Sachs-Str. 5, D-97424 Schweinfurt

Internal oxidation is of great technical importance as effective dispersion-hardening method or undesirable side effect to steel heat treatments. Reaction kinetics is usually described by Wagner’s theory that is designed for laboratory conditions but does not sufficiently cover industrial operations due to the restriction to homogeneous concentration distributions of the less noble component M within the matrix metal, isobaric and isothermal processes. In order to overcome these limitations, a computer model based on iterative solution of Fick’s law for the in-diffusion of oxygen with arbitrary initial distribution of M atoms is proposed. The solubility product and the stoichiometry factor of the precipitating oxide define the mass balance relationship. For homogeneously dissolved M atoms and isothermal-isobaric reaction conditions, it is shown that the results agree excellently with Wagner’s theory and experimental data. Heterogeneous M distributions as well as nonisobaric and/or nonisothermal internal oxidation are accessorily covered by the new model. Illustrative processes are calculated and the results are discussed in detail.