Crystallization, mechanical and corrosion properties of Zr-Cu-Ni-Al-Nb bulk glassy alloys

Zr_65-xCu_17.5Al_7.5 Ni₁₀Nb_x bulk metallic glasses (BMGs) with x = 0, 2 and 5 were prepared by water-cooled copper mold casting. X-ray diffraction and differential scanning calorimetry revealed that the addition of Nb changes the crystallization pathway of the base alloy and promotes an initial formation of icosahedral quasicrystals. The mechanical properties of the BMGs prepared were measured with MTS in a mode of quasi-static compression. It was found that the addition of an appropriate amount of Nb significantly enhances the compression strength and plastic strain with the maximum value of σ_b = 1741 MPa and ε_p = 5.0% for the BMG containing 5at% Nb. In addition, the corrosion behavior of the BMGs was investigated in 3% NaCl aqueous solution by electrochemical measurements. It showed that the BMGs with different compositions are all spontaneously passivated with passive current density of 10^-6-10^-5 A/cm², which is three orders of magnitude lower than that of 1Cr18Ni9Ti stainless steel. The corrosion resistance of the BMGs can be further enhanced with the addition of Nb, as indicated by the increase in pitting potential with the increase of Nb content.