A journey from bulk brass to nanobrass: a comprehensive study showing structural evolution of various Cu/Zn bimetallic nanophases from the vaporization of brass

Abstract

This paper presents the structural and morphological analysis of various Cu/Zn based nanoparticles evolved from bulk brass under different experimental conditions. Vaporization of bulk brass in a solvated metal atom dispersion (SMAD) method results in dealloying of brass into Zn and Cu atoms. Subsequent in situ nucleation and growth of dealloyed components yields Cu/Zn@Cu core-shell nanocomposites. The behavior of these nanocomposites under different heating conditions is studied in detail. Solid state annealing generates brass nanoparticles going through several phases of Cu-Zn phase diagram such as η-CuZn₅, γ-Cu₅Zn₈, β-CuZn (observed as martensite) and α-CuZn in sequence. Whereas, a digestive ripening process which involves refluxing of nanocomposites prepared with capping agents imparts spherical morphology and significantly brings down the size and size distribution of the particles. A detailed characterization of refluxed nanocomposites demonstrates certain processes such as diffusion of Zn atoms and segregation of Cu and Zn phases.