Recrystallization in internally oxidized Cu-Ag-Al alloys

Abstract

The isothermal recrystallization kinetics of rolled Cu-Ag alloys containing up to 0.9 vol % alumina have been followed through hardness measurements; and nucleation rates have been obtained by X-ray back-reflection techniques. Electron microscopic studies have been carried out to characterize the as-deformed structures and the structural changes occurring during the annealing process. The recrystallization of the alloys was either accelerated or retarded as the alumina content increased. This effect has been found to depend both on the dispersion parameters and the degree of deformation. The recrystallization behaviour of these alloys is controlled primarily by the nucleation process. Nucleation occurred after an incubation period and involved the formation of subgrains from the cell structure and their subsequent growth to a viable size. The difficulty of the formation of viable nuclei has been attributed to the particle restraint on sub-boundary migration and to the lack of heavily distorted regions in the defect structure. The rate of nucleation was a function of time and found to depend on the dispersion, initial deformation and the temperature of anneal. The process of grain boundary migration during recrystallization was anisotropic.