Microstructure and Corrosion Properties of Nickel Aluminum Bronze (NAB)

Taking the commonly used marine nickel-aluminum-bronze materials at home and abroad (domestic bracket S1, imported rudder blade S2, imported propeller S3) as the research object,and the microstructure, second phase composition and corrosion resistance of these samples were studied by OM, SEM, weight loss method and electrochemical workstation. The results showed that the microstructures of S1, S2 and S3 were mainly composed of α and κ (κ_Ⅱ, κ_Ⅲ, κ_Ⅳ) phases, among which κ_Ⅱ and κ_Ⅲ were Ni-rich phases. In 3.5%NaCl solution, the corrosion rate of S1 sample was the highest, and the corrosion rate of S3 was the lowest. The interface charge transfer resistance was the main factor affecting the corrosion process. The interface charge transfer resistance of S3 were the largest (3 098 Ω), and its surface corrosion products were mainly composed of Al₂O₃, Cu₂Cl(OH)₂ and (CuNi)₂Cl(OH)₃.