Glass formation, corrosion behavior and mechanical properties of bulk glassy Cu-Hf-Ti-Nb alloys

Bulk glassy (Cu0.6Hf0.25Ti0.15)100-xNbx (x = 0-8 at.%) alloys with maximum diameters of 2.5-4 mm were produced by copper-mold casting. The corrosion rates in 1 N HCl and 3 mass% NaCl solutions significantly decrease with an increase in Nb content. The 6 at.% Nb alloy shows distinct spontaneous passive region in the HCl solution. The alloys with a larger amount of Nb are spontaneously passivated with lower passive current densities and higher pitting corrosion potentials in the NaCl solution. X-ray photoelectron spectroscopy analysis revealed that the formation of Hf-, Nb- and Ti-enriched surface film on the alloys could be responsible for the high corrosion resistance of the Cu-Hf-Ti-Nb alloys in HCl and NaCl solutions. Young’s modulus, compressive fracture strength and compressive plastic strain are 130 GPa, 2405 MPa and 2.8%, respectively, for the 4 at.% Nb alloy, 126 GPa, 2305 MPa and 2.1%, respectively, for the 8 at.% Nb alloy.