Microstructure and Mechanical Properties of High Strength–Ductility Cu-Zn-Al-Fe β-Brass Alloys

In this study, Cu-Zn-Al-Fe β-brass alloys were prepared through homogenization annealing and hot-rolling annealing. The effects of Zn and Al contents on the microstructure and mechanical properties of β-brass alloys were assessed. The results show that Cu-Zn-Al-Fe β-brass alloys comprise β(CuZn) matrix phases and β₁(FeAl) phases with three orders of magnitude: micron, submicron, and nano. By employing appropriate Zn and Al contents, excellent microstructures featuring diffusive nano-β₁(FeAl) can be achieved. However, excessive amounts of Zn and Al promote the formation of a brittle γ(Cu₅Zn₈) phase, which seriously affects the properties of the alloy. After compositional optimization, two alloys exhibit excellent overall mechanical properties. The ultimate tensile strength, yield strength, and elongation were 673.9 MPa, 410.3 MPa, 17.9% for Cu-30Zn-6.5Al-2.5Fe alloy, and 611.1 MPa, 350.2 MPa, and 25.0% for Cu-28Zn-6.5Al-2.5Fe alloy, respectively. The excellent overall mechanical properties can be attributed to a combination of factors, including the synergistic precipitation strengthening of β₁(FeAl) at the micron scale (Orowan mechanism) and the nanometer scale (shear mechanism), solid solution strengthening induced by the addition of Zn and Al, and dislocation strengthening provided by the formation of a large number of dislocations after rolling. This study provides an essential reference for preparing high-performance brass alloys and helps to broaden the application of β-brass in industry.