Microstructure and Mechanical Properties of Cu-Ag-Zr Alloy

• Published in: Journal of materials engineering and performance Vol. 22; no. 12; pp. 3884 - 3889
• Main Authors: Krishna, S. Chenna, Tharian, K. Thomas, Pant, Bhanu, Kottada, Ravi S.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.12.2013; Springer
• Subjects: Applied sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Corrosion and Coatings; Elasticity. Plasticity; Engineering Design; Exact sciences and technology; Heat treatment; Materials Science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Production techniques; Quality Control; Reliability; Safety and Risk; Thermomechanical treatment; Tribology; electron microscopy; high-temperature properties; aging; Cu-Ag-Zr alloy; Ultimate strength method; Ageing; Rolling; Zirconium alloy; Copper base alloys; Precipitate; Forging; Solution heat treatment; Transmission electron microscopy; Transition metal alloy; Silver alloy; Yield strength; Vacuum induction furnace; Microstructure; Thermomechanical treatment
• ISSN: 1059-9495; 1544-1024
• DOI: 10.1007/s11665-013-0659-z

The Cu-3Ag-0.5Zr alloy was produced by vacuum induction melting and subsequently processed through hot forging and rolling. Detailed microstructural characterization of solution-treated (ST) specimen shows three types of phases: Cu matrix, zirconium-rich phase, and Cu-Ag-Zr intermetallic phase. Transmission electron microscopy studies together with energy-dispersive x-ray spectroscopy analysis established the presence of Zr-rich large particles in the ST condition. Aging at 450 °C for 4.5 h after solution treatment resulted in the formation of uniformly distributed fine spherical silver precipitates with an average diameter of 9.0 ± 2.0 nm. Consequently, room temperature yield strength (YS) and ultimate tensile strength (UTS) of the aged specimen increased by 110% and 15%, respectively, compared to those of 120 and 290 MPa of the ST specimen. At elevated temperature, the YS decreased to 146 and 100 MPa at 540 and 640 °C, respectively, for the aged sample. On the contrary, the YS increased to 140 MPa at 540 °C, and thereafter a decrease was observed with a value of 105 MPa at 640 °C for the ST sample. This decrease in YS at higher temperatures is attributed to coarsening of precipitates and dissolution of the precipitates, whereas an increase in YS is attributed to in-situ aging of the samples.