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

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 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 FeAl 3 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 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.