Effects of heat treatment processes on the microstructures and properties of powder metallurgy produced Cu–Ni–Si–Cr alloy

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 619; pp. 221 - 227
• Main Authors: Wang, Huei-Sen, Chen, Hou-Guang, Gu, Jhen-Wang, Hsu, Cheng-En, Wu, Chung-Yung
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 01.12.2014; Elsevier
• Subjects: Age hardening; Applied sciences; Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder; COPPER ALLOYS (40 TO 99.3 CU); Copper base alloys; Cross-disciplinary physics: materials science; rheology; Electron microscopy; Exact sciences and technology; Hardness; HEAT TREATING; Heat treatment; Materials science; Mechanical characterization; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Microstructure; MICROSTRUCTURES; Nanostructure; Non-ferrous alloys; Optimization; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Phase transformation; Physics; Powder metallurgy; POWDER METALLURGY PROCESSES; Powder metallurgy. Composite materials; POWDERS; Production techniques; PROPERTIES; Solid solution, precipitation, and dispersion hardening; aging; Technology; Tensile strength; Thermal properties; Treatment of materials and its effects on microstructure and properties; Phase transformation; Powder metallurgy; Electron microscopy; Mechanical characterization; Non-ferrous alloys; Age hardening; Grain size; Delta phase; Heat treatment; Ageing; Mechanical properties; Precipitate; Hardness; Tensile strength; Thermal properties; Solution heat treatment; Thermal conductivity; Microstructure; Copper alloy
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2014.09.098

To obtain optimal microstructures and properties of a powder metallurgy produced (P/M) copper alloy, this research designed a series of solution and aging heat treatment parameters for a P/M Cu–7.4Ni–1.3Si–1.2Cr alloy. After heat treatment, the variation in their microstructures, thermal properties and mechanical properties were investigated. The microstructure analysis suggested that the hardness or tensile strength increased after an aging heat treatment due to the large number of nanometer-sized precipitates of β-Ni3Si and δ-Ni2Si phases that were formed. The optimal heat treated P/M copper alloy (8-h solution heat treatment at 970°C followed by 6-h aging at 450°C) had an extremely good combination of an average sub-grain size (<30μm), an average tensile strength (up to 820MPa) and an average thermal conductivity (110W/mK), which offers possibilities for application in mold tooling.