Tailoring the surface characteristic of metallic glass for wettability control

Bulk metallic glasses (BMGs) have attracted broad research interest in industrial and commercial fields due to their outstanding mechanical and physical properties. Achieving controlled manipulation of their surface wettability is expected to further improve their applicability. In this study, the functional MG surfaces with various wetting behaviors (including superhydrophilicity, superhydrophobicity, gradient wettability, coexistence of superhydrophilicity and superhydrophobicity) were fabricated by controlling the surface microstructure and chemical composition, which were achieved by laser processing and low-temperature heat treatment. The laser-patterned MG surface with hierarchical micro/nanostructures showed hydrophilicity, and it turned to hydrophobicity after heat treatment, which could be attributed to the adsorption of organic matter from the ambient air. The fabricated gradient wetting surface achieved directional transport of droplets, and the constructed extreme wetting contrast surface exhibited good ability in controlling the spreading of droplets.