Surface Modification of LPBF Ti6Al4V Through In Situ Nitrogen-Assisted Laser Surface Remelting

Abstract

Laser surface remelting is a widely used method for surface modification of titanium and related alloys, particularly to enhance its workability in the biomedical industry through surface nitriding. The present work aims to develop the nitride surface over the laser powder bed fusion (LPBF)-processed Ti6Al4V substrate by introducing the nitrogen environment in the build chamber during the remelting. The effects of different laser power and laser scan speeds were studied over the surface topography and elemental changes of the remelted surface. The result shows an increase in surface roughness with selective laser remelting, which could enhance cell proliferation or osseointegration, which is advantageous for biomedical applications. Energy-dispersive X-ray (EDX) results show a significant increase in nitrogen content in terms of weight percentage for the in situ remelted surface. X-ray diffraction (XRD) phase analysis shows the presence of titanium (Ti) and aluminum (Al) nitride peaks, and X-ray photon-electron spectrometry (XPS) also indicates the formation of nitrogen bonds with Ti and Al, which were initially missing in the substrate. The results reported here confirm the nitride surface formation over the substrate due to the in situ remelting under the nitrogen environment for the LPBF-processed Ti6Al4V, which could be used for improved biomedical applications.