Effects of Alloy Chemistry on the Corrosion of FeNi Metal-Metalloid Metallic Glasses Available to Purchase

The polarization characteristics of Fe₄₀Ni₄₀P₁₄B₆ and Fe₄₀Ni₃₈Mo₄B₁₈ metallic glasses have been determined in 1 N H₂SO₄ and 1 N HCl. Results have been compared with those for metallic glasses of other compositions and with results for metalloid-free crystalline alloys. Phosphorus enhances the ability of metallic glasses to passivate by decreasing the anodic current in the active region and is enriched in the near-surface of the alloy in the form of a pre-passive black film containing nickel and iron. The behavior of iron-nickel metallic glasses containing boron as the only metalloid element does not significantly differ from boron-free crystalline alloys of similar metallic composition. On the other hand, glasses with phosphorus additions are markedly more corrosion resistant than either their crystalline counterparts or the boron-containing glasses. Addition of molybdenum without phosphorus to a metallic glass does not appreciably improve the corrosion resistance, and FeNiBMo metallic glasses will not passivate in 1 N HCl.