Microstructures and elevated temperature properties of rapidly solidified Cu-3Ag-0.5Zr and Cu-3Ag-0.5Zr-0.4Cr-0.35Nb alloys

Gas atomized Cu-3Ag-0.5Zr and Cu-3Ag-0.5Zr-0.4Cr-0.35Nb (wt.%) powders were compacted by hot isostatic pressing (HIP) and followed by forging. The microstructures and tensile properties at room and elevated temperatures (400 °C, 450 °C and 500 °C) were investigated. The continuous Ag precipitates (5–25 nm) and Cu₄AgZr (200–500 nm) particles are the main strengthening phases in the Cu-3Ag-0.5Zr alloy. The yield strength and ultimate tensile strength at room temperature are enhanced by 104 MPa and 83 MPa, respectively, due to the introduction of Cr₂Nb (50–80 nm) particles. Besides, the strength at elevated temperatures is also improved. For both the alloys, the discontinuous Ag precipitates near the grain boundaries result in a weak grain boundary cohesion when tested at 450 °C, leading to the lowest elongation. The Cr₂Nb and Cu₄AgZr particles are extremely stable when tested at 500 °C, which benefits to the performance enhancements at elevated temperatures.