Copper Nanocrystallization in Anodic Oxide Films of Ti–Cu‐Based Bulk Metallic Glass and Its Effect on the Corrosion Resistance and Cytocompatibility

This study investigates anodic surface modification of the Ti 47 Cu 38 Zr 7.5 Fe 2.5 Sn 2 Si 1 Ag 2 bulk metallic glass in a nontoxic potassium pyrophosphate electrolyte and its impact on corrosion behavior and cytocompatibility. The treatment forms bilayered oxide films (20–90 nm) via selective Cu dealloying and Ti/Zr oxide formation. Analyses by transmission electron microscopy and glow discharge optical emission spectroscopy reveal a dense inner amorphous layer and a porous outer layer containing metallic Cu nanocrystals, formed through Cu mobilization and reduction. Electrochemical testing demonstrates that anodization at 1.3 V vs. saturated mercury sulfate electrode significantly enhances corrosion resistance in chloride‐containing phosphate‐buffered saline and reduces Cu ion release by approximately 50% compared to the untreated state. Contact angle measurements confirm increased surface hydrophilicity due to the Ti/Zr oxide matrix. Biological evaluation shows that this optimized surface promotes human bone marrow stromal cell spreading and focal adhesion formation. It results in a 4.5‐fold increase in cell proliferation and elevated activity of the osteogenic marker tissue nonspecific alkaline phosphatase, indicating enhanced osteogenic differentiation. These findings highlight that controlled anodization in a nontoxic pyrophosphate electrolyte can tailor surface oxide structure and composition, simultaneously improving corrosion resistance, cytocompatibility of Ti–Cu‐based metallic glasses for advanced biomedical implants.