Electrochemical and XPS studies of a Nb-containing Ti-based glass-forming alloy system in H₂SO₄ solution

The corrosion behaviors of Ti₄₀Zr₂₅Ni_{12 -x}Nb_xCu₃Be₂₀ (x = 0, 4, 8, and 12 at.%) alloys in 0.5 mol/L H₂SO₄ solution were studied, aiming to establish the relationship between Nb content and corrosion resistance. The addition of Nb element gives rise to a clear microstructural evolution, from a completely amorphous structure for the alloys without Nb and with 4% Nb alloys to an amorphous/crystalline composite structure for the alloys with 8% and 12% Nb. The alloy with higher Nb content exhibits better corrosion resistance, which can be attributed to the formation of Ti^{4 +}-, Zr^{4 +}-, and Nb^{5 +}-enriched highly protective surface film in corrosive solutions.