材料期刊网

The novel nanostructure of AI and AI-Fe were prepared by ball milling alumina with elemental Fe. The kinetics and nanostructure dependence of high temperature low stress Newtonian creep of AI and AI-0.3%Fe have been investigated and compared with the predications of the Nabarro-Herring (N-H) theory of directional diffusion. A simple theory based on the climb controlled generation of dislocations from a fixed density of sources is developed to explain the observed behavior. The dislocation density increases and subgrains form during the creep. Also, the presence of precipitates of FeAI3 reduces the creep rate of AI by absolute faster of 100 at the same stress and temperature, in spite of the fact that the grain size in the AI-0.3%Fe alloy is smaller by a factor of about 100 nm. The reduction of grain size to the nanometer scale improves their mechanical properties. Electron diffraction methods combined with transmission electron microscopy (TEM) and scanning electron microscopy (SEM) studies are a convenient and powerful technique for the characterization of the phases and grain structure of the resulting materials.