Electrochemical Behavior of Novel Co-Al-W Alloys in Sodium Chloride Solutions

Corrosion behaviors of novel Co-Al-W alloys in NaCl solutions with different pH values at room temperature were investigated by electrochemical techniques.The microstructure and composition of the tested samples were investigated by SEM/EPMA.The results showed that Co-Al-W alloys of different chemical compositions with various tungsten contents suffered from serious pitting corrosion and pits located at grain boundaries.The pitting corrosion resulted from the electro-migration of Cl- into the pits from the buck solution.The pitting corrosion resistance of novel Co-Al-W alloys gradually increases with increasing the content of tungsten.However,the corrosion resistance of Stellite 6 is better than that of Co-Al-W alloys in neutral NaCl solutions.