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 degrees C, 450 degrees C and 500 degrees 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 degrees C, leading to the lowest elongation. The Cr2Nb and Cu4AgZr particles are extremely stable when tested at 500 degrees C, which benefits to the performance enhancements at elevated temperatures. (C) 2019 Elsevier B.V. All rights reserved.