Microstructure and wettability of the micro-laminated Ti6Al4V/304 stainless steel composite fabricated by diffusion bonding

Laminated composites have been extensively researched due to their excellent mechanical properties, but their application in superwetting fields has been rarely reported. In this work, the surfaces with extreme wettability were prepared based on laminated composites. The Ti6Al4V/304 stainless steel (304 SS) micro-laminated composites were fabricated by diffusion bonding the Ti6Al4V foils and 304 SS foils with the thickness of 10-50 mu m in vacuum. The typical interfacial microstructure and the effect of diffusion temperature on the microstructure were investigated. The bonded interface of joints is mainly composed of beta-Ti, Ti2Ni, FeTi, Fe2Ti, Fe-Cr from the Ti6Al4V side to the 304 SS. The effect of diffusion temperature on the microstructure was researched. Based on the prepared Ti6Al4V/304 SS micro-laminated composites, an array structure with micro grooves was fabricated through the simple chemical etching. The 304 SS foils were etched to form grooves, while Ti6Al4V foils still remained as bulges. Due to surface modification and rough morphology, the etched surfaces exhibited the excellent hydrophobicity. Increasing the width and depth of grooves and decreasing the width of bulges led to the higher water contact angles and improved hydrophobicity. The highest water contact angles of 148.3 degrees has been achieved under the conditions of grooves with a width of 50 mu m, a depth of 60 mu m, and the bulges with a width of 10 mu m. The surfaces exhibited nearly superhydrophobicity and performed self-cleaning property. The processing method of this work could expand the application of laminated composite in extreme wettability fields.