Kinetics and Nanostructure Dependence of High Temperature-Low Stress Creep of Al and Al-0.3%Fe

Abstract

The novel nanostructure of Al and Al{Fe were prepared by ball milling alumina with elemental Fe. The kinetics and nanostructure dependence of high temperature low stress Newtonian creep of Al and Al{0.3%Fe have been investigated and compared with the predications of the Nabarro{Herring (N{H) theory of directional difiusion. A simple theory based on the climb controlled generation of dislocations from a flxed 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 FeAl3 reduces the creep rate of Al by absolute faster of 100 at the same stress and temperature, in spite of the fact that the grain size in the Al{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 difiraction 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.