Nickel Aluminium Bronze Alloys with Enhanced Erosion-Corrosion Resistance and Mechanical Strength

Owing to their excellent wear and corrosion resistance and their good mechanical properties, nickel aluminium bronze alloys (NABs) are ideal materials to manufacture components of marine industry. In this work, NABs with nominal composition Cu-10Al-5Ni-4Fe-1Mn (wt.%) were obtained following advanced manufacturing technologies based on powder metallurgy, like press and sintering and HIP. The influence of processing conditions during sintering, HIPing and final heat treatments on the final microstructure is evaluated. Mechanical properties (hardness, tensile and Charpy impact tests) as well as corrosion and erosion-corrosion resistance are also presented. It has been found that an adequate selection of the starting powders and sintering and HIP conditions leads to dense materials. Final heat treatments are responsible for further microstructural refinement and dissolution of detrimental brittle phases, like martensitic β or coarse rosette κI, resulting in enhanced mechanical strength and resistance to erosion-corrosion in seawater, as compared to conventional cast NABs.