Formation, evolution and characterization of nanoporous structures on the Ti6Al4V surface induced by nanosecond pulse laser irradiation

Manipulating materials at nanoscale is challenging but rewarding. Nanostructures exhibit some unique properties distinguished from macroscopic bulk materials, so fabrication of nanostructures on the material surface is beneficial to broaden their functional applications. In this study, by nanosecond pulse laser irradiation in nitrogen atmosphere, it was found that unique nanoporous structures could be formed on the Ti6Al4V surface. The effects of laser parameters including the laser power, overlap rate, scanning speed, and repetition frequency on the formation and evolution of the nanoporous structures were systematically investigated. By changing the laser parameters, the nanoporous structures with various porosities could be easily achieved on the Ti6Al4V surface. According to the structural evolution and chemical composition, the formation mechanism of the nanoporous structures was discussed. Furthermore, by characterizing the micro-mechanical properties and wettability, it was found that the surface with nanoporous structures exhibited similar surface hardness but improved tribological performances compared to the original Ti6Al4V surface, and the surface wettability could be tuned. This study provides a simple method for fabricating nanoporous structures on the Ti6Al4V surface, which would broaden its functional applications.