Pitting corrosion of intermetallic compound Ni3(Si,Ti) in sodium chloride solutions

The pitting corrosion of intermetallic compound Ni3(Si,Ti) was investigated as functions of test temperature and chloride concentration in sodium chloride solutions by using a potential step method. In addition, the pitting corrosion of solution-annealed austenitic stainless steel type 304 and pure nickel was also studied under the same experimental condition for comparison. The pitting potential obtained for the intermetallic compound decreased with increasing chloride concentration and test temperature. A critical chloride concentration below which no pitting corrosion took place was found to exist and to decrease with increasing test temperature. The specific pitting potential at the critical chloride concentration also decreased with increasing test temperature. In addition, the pitting potential at various constant chloride concentrations above the critical chloride concentration decreased with increasing test temperature. The pitting potential of Ni3(Si,Ti) was higher than pure nickel, but lower than that of type 304.