CuZn3x

CuZn3x is a copper‑zinc alloy composition in which the zinc content is expressed as a variable fraction, represented by the parameter x in the stoichiometric notation CuZn3x. The notation indicates that for every copper atom present, the alloy incorporates 3x zinc atoms, allowing the overall zinc concentration to be tuned between pure copper (x = 0) and high‑zinc brasses (x approaching 1). This flexible composition range makes CuZn3x alloys useful in a variety of engineering and decorative applications where the balance between ductility, strength, and corrosion resistance can be precisely adjusted.

The crystal structure of CuZn3x alloys typically adopts a face‑centered cubic (FCC) arrangement when zinc concentrations are below about 30 wt %. At higher zinc levels, the β‑brass (CuZn) phase forms, featuring a body‑centered cubic (BCC) lattice. In some intermediate regimes, a mixture of FCC and BCC phases appears, producing a multiphase microstructure that can enhance toughness or modify electrical conductivity.

Physically, increasing zinc content generally reduces electrical conductivity but improves hardness and corrosion resistance. Tensile strengths can reach from 200 to 800 MPa depending on the x value and heat‑treatment schedule. The alloys also exhibit a lower coefficient of thermal expansion than pure copper, making them suitable for components subjected to temperature cycling.

Industrial uses of CuZn3x include electrical connectors, cable sheaths, and printed circuit board substrates due to their conductivity and mechanical robustness. Decorative metalwork, such as ornamental hardware and sculpture, often employs zinc‑rich variants for their desirable coloration and corrosion resistance. In some catalytic processes, CuZn3x has been investigated for its potential as a support for active metal sites, particularly in CO₂ reduction and fuel‑cell reactions.