Evolution of microstructure, mechanical and corrosion properties of nickel aluminum bronze alloys processed by three-stage rotary swaging

In this study, three-stage cold rotary swaging combined with intermediate annealing was employed to fabricate nickel aluminum bronze rods with a total area reduction ratio of 84%. The evolution of microstructure, mechanical properties and corrosion properties was systemically investigated. It was found that the sample before the deformation exists lamellar κ Ⅲ phases, which transformed to spheroidized morphology during the three-stage rotary swaging. In addition, the matrix α grain was significantly refined from about 5 μm to 1 μm. The combination of the spherical second phases and fine grain size induced an enhanced yield strength of 584 MPa and elongation of 20.4% compared to 544 MPa and 15.5% of the initial sample. The electrochemical result showed that the corrosion properties of the initial sample and the deformed sample were similar. The current studies suggested that the three-stage cold rotary swaging is a promising route to improve the mechanical properties of NAB alloys without sacrificing the corrosion properties.