Role of interfaces on microstructure refinement and mechanical properties of severe plastically deformed copper and copper-silver eutectic

Abstract

The process of microstructural refinement during deformation by high pressure torsion (HPT) of commercially pure copper (Cu-B), copper powders (Cu-P) and cast copper silver eutectic alloy (CuAg-E) were investigated. The presence of a surface oxide layer or of immiscible silver lamellae leads to much finer grain size. A saturation in microstructural refinement was attained in both Cu-B and Cu-P samples, while the CuAg-E sample showed a linear hardening propensity down to a 30 nm interlamellae spacing. The possible mechanisms for strengthening in the CuAg-E alloy are further discussed in view of the evolution of interlamellae spacing with applied shear strain.