Formation and Corrosion Behavior of Mechanically-Alloyed Cu–Zr–Ti Bulk Metallic Glasses

Cu60Zr30Ti10 metallic glass powder was prepared by mechanically alloying a mixture of pure Cu, Zr, and Ti powders after 5 h of milling. Cu60Zr30Ti10 bulk metallic glass (BMG) was synthesized by vacuum hot pressing the as-milled Cu60Zr30Ti10 metallic glass powder at 746 K in the pressure range of 0.72–1.20 GPa, and the structure was analyzed through X-ray diffraction and transmission electron microscopy. The pressure could enhance the thermal stability, and prolong the existence, of the amorphous phase inside the Cu60Zr30Ti10 powder. Furthermore, the corrosion behavior of the Cu-based BMG in four corrosive media was studied using a potentiodynamic method. The Cu60Zr30Ti10 BMG exhibited a low corrosion rate and current density in 1 N solutions of H2SO4, NaOH, and HNO3. X-ray photoelectron spectroscopy results revealed that the formation of Zrand Ti-rich passive oxide layers provides a high corrosion resistance against 1 N H2SO4 and HNO3 solutions, and the breakdown of the protective film by Cl− attack was responsible for pitting corrosion in a 3 wt % NaCl solution. The formation of oxide films and the nucleation and growth of pitting were analyzed through microstructural investigations.