A critical analysis of the composite model as applied to high-temperature creep of Al and an Al–Mg alloy

Abstract The composite model which has been created by Mughrabi, and developed by several other researchers, is analyzed with respect to high-temperature creep of Al and an Al–Mg alloy. Data for structural parameters such as local and global internal stresses, and dislocation densities have been obtained from X-ray line profile analyses and stress dip tests. Based on the composite model, quantitative relations have been derived which convert the internal stresses gained from X-ray profile analysis into those obtained from stress dip tests. This allowed for a detailed check of the composite model and its formalism describing local and global external and internal stresses, and local and global dislocation densities, during creep at high temperatures. While the local and global internal stresses show an excellent coincidence, the dislocation densities and subboundary volume fractions derived from experiment and modelling show certain deviations; however, these can be related to simplifications of equations ...