Electrochemical and chemical corrosion behaviors of the in-situ Zr-based metallic glass matrix composites in chloride-containing solutions

The Zr58.5Ti14.3Nb5.2Cu6.1Ni4.9Be11 metallic glass matrix composites (MGMCs) were prepared by copper mould casting. The corrosion resistance and the pitting susceptibility of Zr-based MGMCs were tested in 1M KCl, 1M NaCl, and 0.5M CaCl2 solutions by potentiodynamic polarization tests and chemical immersion measurements. As a result, the corrosion current density is the smallest, and the pitting potential is the largest in 0.5 M CaCl2 solutions due to the smallest radium of Ca2+, which indicates that the Zr-based MGMCs have better corrosion resistance. On the contrary, the corrosion resistance of Zr-based MGMCs in 0.5M CaCl2 solutions is poor during the immersion tests, which corresponds to the result of roughness. Further investigation of XPS indicates that oxide films are mainly composed of ZrO2, TiO2, and Nb2O5 formed on the surface of the Zr-based MGMCs. However, the oxide films formed in 0.5M CaCl2 solutions possess the worst protective effect due to the lower contents of ZrO2, TiO2, and Nb2O5, whereas the oxide films formed in 1M NaCl solutions possess the best protective effect.