Microstructural evolution and strengthening mechanisms in cold-rolled Cu–Ag alloys

Abstract

In this work, the microstructural evolution and strengthening mechanisms of pure copper and Cu–Ag alloys subjected to cold rolling were experimentally investigated. Significant strain strengthening occurred during cold rolling, with steady-state strengths of 424, 666, and 686 MPa achieved upon large-strain cold rolling in pure copper, Cu–10Ag, and Cu–15Ag, respectively. Microstructural examination was performed to quantitatively determine the strengthening contributions of the grain boundaries, dislocations, Ag dispersoids, and solute atoms. Dislocation strengthening and boundary strengthening were shown to be the dominant strengthening mechanisms in the cold-rolled Cu–Ag alloys at steady state, accounting for >80% of the strengthening. In addition, Ag addition increased the limiting concentration of dislocations and subgrain boundaries in the Cu solid solution, resulting in higher steady-state strength of the cold-rolled Cu–Ag alloys relative to that of pure copper. The high Ag concentration also led to a larger volume fraction of the high-strength eutectic colony in Cu–15Ag, resulting in higher strength than that of Cu–10Ag.