Analytical modeling of stress and strain of symmetrically oxidized metal

During high temperature isothermal oxidation, a plane of oxide molecules is inserted in each oxide grain boundary. These oxide scales grow laterally and thicken in a columnar microstructure to generate a lateral growth strain. But as the oxide scales are constrained by the underlying metal, the metal constraint produces a net in plane compressive stress in the oxide scales. To balance a compressive stress in the oxide scales, a net in plane tensile stress is generated in the metal, which results creep elongation of an oxide/metal composite. Based on this mechanism, the present paper provides a simplified modeling approach to predict an evolution of the stresses and strains in the oxide/metal composite considering the lateral growth strain of the oxide and creep strain of the metal and oxide. Oxide stress variation due to the creep properties of the oxide/metal composite such as creep indexes (m and n) and creep constants (A(ox) and A(m)) is provided for the notional mechanical properties. Oxide stress variation due to the lateral growth constant D-ox and oxide kinetics parabolic constant k(p) is also discussed. Finally, the modeling results are compared with the experimental results obtained for FeCrALY and Ni alloy to highlight the importance of the proposed modeling. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4740048]