Comparative investigation on densification, mechanical and wear characteristics of spark plasma-sintered refractory nitride-reinforced Ti6Al4V-based composites

Composites of Ti6Al4V reinforced with 1, 3, and 5 wt. % of three distinct refractory nitrides: h -BN, TiN, and AlN nanoparticles, were fabricated using spark plasma sintering (SPS). The sintered composites were characterized and investigated comparatively in terms of their microstructure, phase composition, densification, mechanical, and wear characteristics, achieved through the use of field-emission gun scanning electron microscopy, X-ray diffraction, Archimedes’ method, nanoindentation technique, and ball-on-disk wear tests. The unreinforced alloy presented a two-phase microstructure comprising α and β phases. Reinforcement with refractory nitrides resulted in significant microstructural alterations and the development of nitride-rich secondary phases. The composites’ relative densities declined with increasing reinforcement content, falling from 98.4 to 97.4% for h -BN, 98.62 to 97.63% for TiN, and 98.64 to 95.14% for AlN. Compared to the unreinforced alloy, the nanoindentation results established that the sintered composites exhibit a continuous appreciation in hardness and elastic modulus with the highest values (70.782 ± 0.794 GPa and 356.76 ± 4.05 GPa, respectively) shown by Ti6A4V-5 wt. % h -BN. In addition, the unreinforced alloy exhibits a higher specific wear rate at each applied load than the composites, which is attributed to the improved hardness features of the refractory nitride-reinforced Ti6Al4V-based composites.