Powder metallurgy processing of nickel aluminum bronze: correlation between microstructure and mechanical performance

Nickel aluminum bronze alloys (NABs) are widely used in marine applications due to their exceptional combination of corrosion resistance in seawater, high mechanical strength, and ductility. In this study, fully dense NAB alloys were produced using two distinct Powder Metallurgy (PM) routes: uniaxial pressing and sintering, and Hot Isostatic Pressing (HIP) of encapsulated powder. The influence of these processing methods and the subsequent annealing treatment on the resulting microstructure and mechanical properties were systematically analyzed. This work focuses on correlating the microstructure and mechanical properties of NAB alloys through detailed electron backscatter diffraction (EBSD) analysis. The mechanical properties of the PM alloys surpassed the requirements specified by the EN 1982:2024 standard. Furthermore, the annealing treatment enhanced ductility without compromising strength, attributed to the formation of annealing twins. The findings of this study highlight the significant potential of PM routes to produce NAB alloys. • Fully dense Nickel Aluminum Bronze (NAB) samples were fabricated through powder metallurgy (PM). • Processing route and annealing strongly affect NAB microstructure and phase evolution. • Quantification of β' phase concentration in NAB alloys was achieved through EBSD. • Annealing twins increase ductility of sinter-HIP alloys without compromising strength.