The changes of microstructure and properties in precipitation hardened copper alloys during cold rolling and annealing

During cold rolling and annealing process in precipitating hardened copper alloys, the changes in microstructure, which decide the electrical or mecha nical properties, were mainly brought about by the recrystallization of the matrix and the formation of precipitates in the matrix. To design the opti mum process condition, it is necessary to analyze the characteristics of th e change in microstructure and properties systematically in various copper ahoy systems. The changes in microstructure and properties in Cu-Fe, Cu-Cr and Cu-Ni-Si system alloys were observed experimentally during cold rolling and annealing treatments after solution or pre-aging treatments. The harde nability by the precipitation became larger in order of increasing misfit e nergy, Cu-Fe, Cu-Cr, Cu-Ni-Si system alloy. The suppression effect of recry stallization is dominant in the condition of the pre-aging at 773 K in Cu-C r alloy, and at 973 K in Cu-Fe and Cu-Ni-Si alloys. During the recrystalliz ed grain boundary migration, the effect of interface structure changes betw een the precipitate and matrix was analyzed, based on the boundary pinning theory proposed by Ashby. It seems that misfit energy change in Cu-Ni-Si ah oy, and the chemical energy change by interface structural change of precip itates in Cu-Fe, reduced the boundary pinning energies that affect the rate of recrystallization.