A novel Cu-based BMG composite with high corrosion resistance and excellent mechanical properties

A newly designed (Cu0.6Hf0.25Ti0.15)90Nb10 bulk metallic glass (BMG) composite with an excellent combination of high corrosion resistance and superior mechanical properties was successfully synthesized. The micrometer-sized ductile Nb-rich dendrite phase disperses homogeneously in the glassy matrix. Addition of Nb to the Cu–Hf–Ti alloy results in a significant decrease in the corrosion rates in the solutions examined. The high corrosion resistance of the (Cu0.6Hf0.25Ti0.15)90Nb10 BMG composite is attributed to the formation of Hf-, Ti-, and Nb-enriched highly protective surface films during immersion in acid- and chloride-ion-containing solutions. The composite alloy exhibits a high compressive true yield strength of 2073 MPa and true fracture strength of 2232 MPa together with a large true plastic strain of 14.1%. The embedded micrometer-sized dendrites in the glassy matrix retard inhomogeneous shear deformation and contribute to the large plastic strain.