DEFORMATION-PROCESSED COPPER-CHROMIUM ALLOYS - ROLE OF AGE-HARDENING

A processing technique was developed previously to optimize strength a nd electrical conductivity in deformation-processed copper-chromium wi res. It consists of deformation treatments alternated with a solution plus quench treatment and then with an aging treatment. In the present study, samples were examined by transmission electron microscopy at e ach stage of the optimized process to follow the evolution of microstr ucture. It was shown that this type of processing develops maximum red uction in size of the chromium dendrite phase without breakage and tha t the deformation produces a strong precipitation of the chromium from solid solution. The aging treatment does not produce an age-hardening effect. Rather, it produces precipitation of chromium on the existing chromium filaments and relieves the strain in them so that additional reduction by deformation is possible. Additional experiments on coppe r-niobium alloys, which are not expected to show age hardening, also s upport these conclusions.