Effect of TiN and TiCN additions on spark plasma sintered Ti-6Al-4V

In this study, the microstructural and densification behavior of titanium nitride (TiN) and titanium carbonitride (TiCN) reinforced Ti-6Al-4V were investigated under an applied pressure of 50 MPa, sintering temperatures of 1000-1100 degrees C, heating rate of 100 degrees C/min and dwell time of 10-20 min through spark plasma sintering technique. Results show that the microstructural transformation of the titanium matrix composite comprises of a mixture of lamellar colonies with beta grain boundaries and nanoparticles with an average grain size range of 4.5-6.0 mu m. Furthermore, an addition of nanoceramics TiN/TiCN resulted in microstructural transformation, uniform particle distribution within the metal matrix and along the grain boundary. However, the sintered relative density of the composites decreased with the percentage increase in TiCN, while fully dense composites were obtained at a sintering temperature of 1100 degrees C. Microhardness values of the sintered composites reach a greater level in comparison to Ti-6Al-4V alloy while fracture morphology of the sintered composites with addition of nanoceramics (TiN/TiCN) displayed a transgranular transformation within the matrix accompanied with fine dimple features.