Synergistic improvement of erosion-corrosion resistance and mechanical properties of nickel aluminium bronze alloy by the addition of Cr

The effect of Cr addition on nickel aluminium bronze (NAB) alloy microstructure, mechanical properties, and erosion-corrosion behaviour has been studied. The results show that Cr addition does not change the composition of the precipitated phases, more Cr entered the κ phase and a small amount of Cr solubilized in the matrix, which increase the hardness of the κ and matrix and decrease the potential difference between the κ and matrix. NAB alloy with Cr shows high erosion-corrosion resistance at high flow rate conditions, due to its lower phase potential difference and higher surface hardness. At the flow rate of 3 m·s⁻¹, the corrosion rate is 0.076 mm·year⁻¹, which is ~ 20% lower than that of the unadded Cr sample. Moreover, the corrosion product film contains Cr₂O₃ and Cr³⁺, which improves the densification of the film and raises alloy’s corrosion resistance with Cr addition. The combination of mechanical and corrosion resistant properties may qualify this alloy as a potential candidate material for sustainable and safe equipment.