Deformation and fracture, during cooling, of the alumina scale developed on Fe3Al

The deformation and fracture, during cooling, of oxide scales developed on Fe3Al has been modelled using finite element analysis (FEA). Embedded defects were introduced at the oxide surface and at the oxide/substrate interface; the propagation of these defects and the influence of such propagation on scale spallation was analysed under both elastic and elastic plastic conditions. Stress relaxation associated with the plastic deformation of the substrate delayed scale spallation as indicated by the greater temperature drop required to cause spallation. In this situation, the presence of the oxide surface crack influenced scale spallation in a complex manner. The oxide surface crack did not influence the scale spallation process for the linear elastic analysis, which was solely controlled by the interfacial defect.