Corrosion properties of a Cr₁₃Ni₅Si₂-based metal silicide alloy

Corrosion properties of a near single-phase corrosion-resistant Cr₁₃Ni₅Si₂-based metal silicide alloy were evaluated using anodic polarization and immersion tests in 1 N HCl, 0.5 N H₂SO₄, 1 N NaOH and 3.5 wt% NaCl water solutions, respectively. X-ray photoelectron spectroscopy (XPS) was utilized to investigate the component of surface film spontaneously formed on the alloy in air. Results showed that the alloy had very low corrosion rate in all the electrolytes because of the spontaneous formation of a protective and stable passive film composed mainly of chromium(III) oxide and silicon oxides. In anodic polarization tests, the alloy exhibited excellent electrochemical corrosion resistance in acidic and neutral environments with and without Cl^- ions, while the alloy was less corrosion-resistant in 1 N NaOH solution due to the continuous formation and dissolution of Na₂SiO₃ in NaOH solution.