Effect of heat treatment on microstructure and corrosion behavior of nano-sized TiC reinforced Ti6Al4V composites fabricated by selective laser melting

This study investigates the effect of heat treatment on microstructure and corrosion behavior of 1 wt.% TiC/Ti6Al4V composites fabricated via selective laser melting. The microstructure of the composite was tailored by controlling the solution temperature (940 °C, 970 °C and 1000 °C) and duration (15 min, 60 min, and 120 min). Results show that the volume fraction of the α phase decreases with increasing solution temperature and duration, while the α lath width coarsens accordingly. The volume fraction of the β phase and TiC phase also rises with increasing solution temperature and duration. Both the α→β phase transformation and the precipitation of the TiC phase follow the Johnson-Mehl-Avrami (JMA) kinetic model. Electrochemical tests in 3.5 wt.% NaCl solution demonstrate that solution treatment enhances the corrosion resistance compared to the annealed condition. The corrosion resistance of the samples also varies to some extent depending on the different solution treatments. The sample treated at 970 o C for 120 min exhibited the optimal corrosion resistance. Effect of microstructure on corrosion resistance were also discussed.