Formation of nanocrystalline phases in Cu-Zn system during mechanical alloying

Abstract

The evolution of various nanocrystalline phases in the Cu-Zn system during the course of mechanical alloying of elemental powder blends, manifests a similar sequence of phase formation in all the compositions. Zinc-rich phases were always first to form, which can be attributed to the diversities of diffusivities and diffusion distances in the constituents. The extent of zinc in α- phase becomes significant only after α turns nanocrystalline. The crystallite size of reached a minimum (~18 nm) near the α- β phase boundary, while the β and ε phases showed quite coarse crystallite size due to their low melting points. Alloying was sluggish during dry milling compared to wet milling, or at lower milling speed, which demonstrates the effects of oxidation during milling and lower milling energy.