Tribocorrosion of additively manufactured and wrought Ti6Al4V in a saline environment

Abstract

Laser powder bed fusion (LPBF) and wrought Ti6Al4V were compared from a tribocorrosion perspective in 0.9 % NaCl, distinguishing between mechanical and chemical (oxidative) wear through potential-controlled measurements. The aim was to elucidate the manufacturing- and potential-dependent tribocorrosion mechanisms in a saline environment. While both manufacturing methods resulted in excellent corrosion resistance, the LPBF titanium alloy exhibited a finer, distinct microstructure, higher microhardness, and greater tribocorrosion resistance under applied cathodic and anodic potentials in saline than the wrought alloy. More available slip systems, lower grain boundary density, easier crack formation and propagation at the oxide-subsurface interface, and more oxidized third-body particles were responsible for the higher mechanical and chemical volume loss of wrought samples. These features were related to the microstructural differences; the wrought titanium alloy consisted of a β phase, along with α phase, and a lower grain boundary density, whereas the LPBF alloy possessed α/α′ phases and a higher grain boundary density.