Microstructure stability and tensile properties of Cu-3Ag-1Zr alloy fabricated by rapid solidification and cold rolling

A Cu-3Ag-1Zr alloy was fabricated by rapid solidification and cold rolling. The microstructure stability and tensile properties of this alloy after isochronal annealing at 350-900 degrees C were investigated. The results show that the microstructure of the Cu-3Ag-1Zr alloy after annealing at 350 degrees C for 1 h is dominated by the high-density dislocations, ultrafine grains, low angle grain boundaries (LABs) and second-phase particles (nano-sized Ag and micro-sized Cu4AgZr), which results in a high tensile strength of 637 MPa and moderate elongation of 12%. When annealed at 400 degrees C, the particle stimulated nucleation of recrystallization (PSN) occurs, and the fraction of LABs decreases to 38%, but over 90% of grains are smaller than 2 mu m. The decreased tensile strength (465 MPa) and increased elongation (30%) are closely related to the fully recrystallized microstructure after annealing at 500 degrees C. The alloy exhibits excellent thermal stability when annealed between 500 and 800 degrees C, and no significant coarsening of grains and decrease in strength are observed due to the strong pinning effect of the stable Cu4AgZr particles at boundaries. The coarsening of the Cu4AgZr particles at 900 degrees C leads to the sharp increase in the grain size and drop of strength.