The plastic deformation of 18R long range ordered Cu-Zn-Al single crystals the temperature and strain rate dependence of the critical stress and the influence of dynamic strain aging

Long-range ordered (18R structure) Cu-Zn-Al single crystals with the stacking sequence ABCBCACAB of close packed planes have been plastically deformed in compression. The dislocations move on the basal plane and have the shortest possible translation Burgers vector. The critical resolved shear stress increases with temperature above room temperature and the strain rate sensitivity decreases, reaching negative values at elevated temperatures. The results cannot be explained by an increased friction stress of the moving dislocations due to diffusion induced reordering of the antiphase boundary between the partials. It is instead suggested that diffusion modifies the dislocation configuration, essentially after it gets immobilized at obstacles.