Corrosion Behaviour of Nickel‐Aluminium Bronze (NAB) in Artificial Brackish Water (ABW) and in Sulphide‐Containing Solutions

ABSTRACT Nickel–aluminium bronze (NAB) alloys are used in naval components requiring mechanical strength and corrosion resistance. Sulphides and other sulphur‐containing compounds increase electrolyte aggressiveness and modify corrosion mechanisms in polluted and stagnant marine environments. NAB corrosion behaviour was analysed by potentiodynamic and potentiostatic tests in five solutions: artificial brackish water (ABW, DIN 50905‐4), ABW wherein thioacetamide was replaced by Na 2 S solutions containing 10, 50 and 100 ppm S, and ABW without thioacetamide or Na 2 S (ABW No_Tio ). Corroded surfaces and corrosion products were analysed by optical microscopy (OM) and scanning electron microscopy–energy dispersive X‐ray spectroscopy (SEM–EDS). The results show that thioacetamide acts as an inhibitor, reducing the corrosion rate of NAB and promoting a stratified surface damage morphology. In contrast, Na 2 S‐containing solutions increase corrosion kinetics relative to ABW, promoting inward damage propagation and selective corrosion of the aluminium‐rich β phase. The formation of a thicker and less permeable copper sulphide layer than the oxychloride layer formed in ABW No_Tio may limit anodic dissolution.