Effect of microalloying of Nb on corrosion resistance and thermal stability of ZrCu-based bulk metallic glasses

Bulk metallic glasses (BMGs) of Zr46−xNbxCu37.6Ag8.4Al8 with x = 0, 0.5, 1, 2 and 4 at.% were prepared by copper mould casting. The corrosion resistance of the ZrCu-based BMGs with different Nb contents was carefully examined by weight loss measurements and potentiodynamic polarization tests in 3 mass% NaCl, 1 N HCl and 1 N H2SO4 solutions, respectively. Nb addition improves the newly developed BMGs’ corrosion resistance in chloride-containing solutions and the alloys all exhibit excellent corrosion resistance in 1 N H2SO4. The corrosion behavior of the alloy containing 0 and 4 at.% Nb in phosphate-buffered solution was examined by electrochemical polarization tests. The influence of Nb addition on glass forming ability (GFA), thermal stability and mechanical property was investigated by X-ray diffraction, differential scanning calorimetry and compression tests, respectively. It is found that the addition of Nb can deteriorate the GFA and thermal stability of the base system, but little effect is observed on the mechanical properties, e.g., yielding strength and plasticity, of the ZrCu-based BMG alloys.