The synergistic effect of cavitation erosion and corrosion of nickel-aluminum copper surface layer on nickel-aluminum bronze alloy

A completely nickel-aluminum-copper (Ni-Al-Cu) layer was obtained through thermal diffusion process on a nickel-aluminum-bronze (NAB) substrate. The cumulative mass loss of the NAB alloy during the cavitation erosion tests was about 6.4 times and 5.5 times as large as that of the Ni-Al-Cu layer in distilled water and 3.5 wt% sodium chloride (NaCl), respectively. Electrochemical measurements under quiescence and cavitation erosion conditions were conducted to investigate the synergistic effects of cavitation erosion and corrosion. The results showed that the synergism had measurable effect on the cavitation erosion-corrosion process for both the NAB alloy and the Ni-Al-Cu layer. The total contribution of the cavitation erosion component including WE and WCIE was more than 80% and WE occupied the largest percentage. Thus, the improved cavitation erosion resistance of the Ni-Al-Cu layer was mainly due to mechanical factors, which implied a homogeneous and refined microstructure and the formation of hardened Ni3Al phase. © 2018 Elsevier B.V.