Microstructure evolution and corrosion mechanism of in situ synthesized TiC/TC4 alloy nanocomposites fabricated by laser powder bed fusion

The corrosion mechanism and microstructure evolution of TC4 alloy and TiC/TC4 alloy nanocomposite manufactured by laser powder bed fusion (LPBF) were evaluated comparatively using electrochemical measurements combined with microstructure characterisations. The compelling microstructural results showed that refined grains, fewer defects and stronger texture strength were the dominating internal factor for enhancing the corrosion resistance of TiC/TC4 alloy nanocomposites. Further, a uniform distribution of in situ formed nanoscale TiC reinforcements significantly promoted the formation of [TiCl6]2- complexes, yielding the passivation formed again. These findings revealed that the elevated corrosion performance of LPBF-built TiC/TC4 alloy nanocomposites is due to the nanoscale TiC and strengthened microstructure inhibiting the occurrence of pitting corrosion in the alloy system during the corrosion process.