Oxidation difference of microstructural bands in additive manufactured titanium alloy

In this study, Ti6Al7Nb alloy produced by twin-wire arc additive manufacturing was oxidized at 800°C to identify the oxidation difference induced by heat-affected bands (HABs), which have been widely reported in additive manufactured titanium alloys. The oxidation kinetics proved that HABs with compact β laths have stronger oxidation resistance compared with that of the non-HAB zone. Nb element enriched in β phase promoted Ti3Al to precipitate at the original position of β laths after oxidation, having a similar spacing to the β laths. The formation of compact Ti3Al on HAB beneficially inhibits oxygen diffusion across the oxide scale/matrix interface.