The effect of stacking fault energy on equilibrium grain size and tensile properties of nanostructured copper and copper–aluminum alloys processed by equal channel angular pressing

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2012-10, Vol.556, p.638-647
• Main Authors: Huang, C.X., Hu, W., Yang, G., Zhang, Z.F., Wu, S.D., Wang, Q.Y., Gottstein, G.
• Format: Article
• Language: English
• Subjects: Aluminum; Applied sciences; Binary systems; Copper; COPPER (PURE); Copper base alloys; Cross-disciplinary physics: materials science; rheology; Cu–Al alloy; ECAP; Elasticity. Plasticity; Equal channel angular pressing; EQUILIBRIUM; Exact sciences and technology; Grain size; GRAIN SIZE AND SHAPE; Materials science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Microstructure; MICROSTRUCTURES; Nanocrystalline materials; Nanoscale materials and structures: fabrication and characterization; Nanostructure; Other heat and thermomechanical treatments; Physics; Solid solution, precipitation, and dispersion hardening; aging; Stacking fault energy; STACKING FAULTS; STRAIN HARDENING MECHANISMS; Strength and ductility; TENSILE PROPERTIES; Treatment of materials and its effects on microstructure and properties
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2012.07.041

Pure copper and copper–aluminum alloys (aluminum content of 2.3at%, 7.2at%, and 11.6at% with stacking fault energies (SFEs) of about 48mJ/m2, 21mJ/m2, and 8mJ/m2, respectively) were processed by equal channel angular pressing (ECAP) at room temperature for 8 passes to generate a nanoscale grain size. The effect of SFE on microstructure refinement and tensile properties of these materials were investigated. Microstructural observations indicated that the grain size of as-ECAPed alloy decreased monotonically with increasing Al concentration, i.e. with decreasing SFE. A very low SFE was especially favorable for achieving a true nanocrystalline structure (e.g. d≈57nm in Cu–11.6at% Al) by twinning and shear banding. The tensile strength and uniform elongation of nanostructured copper–aluminum alloys were simultaneously enhanced owing to the significant grain size refinement, solid solution strengthening and enhanced strain hardening capability.