This proposal examines inelastic deformation in metals and associated effects of fatigue and creep on structure evolution, which, in turn, influences the deformation process. The program consists of three related studies: (1) reloading tests to assess the evolution of structure as represented by the mechanical threshold and athermal stress parameters; (2) strain rate change tests to study the kinetics of constant structure deformation during fatigue; and (3) stress change tests designed to discriminate between different theoretical treatments of creep in dispersion-strengthened alloys. Mechanistically-based models are developed to provide quantitative descriptions of deformation. %%% The primary goal of this research is to gain understanding of inelastic deformation processes in order to extend the operating environments of existing structural materials, to develop new materials with improved properties, and to gain better control of forming and manufacturing operations.
