Effect of sintering parameters on densification and microstructural evolution of nano-sized titanium nitride reinforced titanium alloys

The effects of spark plasma sintering (SPS) temperature and time on nano-sized TiN particle dispersed in titanium matrix have been investigated. Ti–6Al–4V and nano-TiN powders were mixed in a T2F Turbula mixer in different proportions (1–4 vol%). The admixed powders were consolidated using SPS while the sintered compacts were characterized using field emission scanning electron microscopy (FE-SEM), equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffractometry techniques. Microindentation hardness and fracture behaviour of the sintered compacts were investigated. Results show that an increase in sintering temperature significantly influences the relative densities from 97 to 99% and microhardness of the composites from 389 to 602 HV_0.1. The microstructural studies as well revealed transformation from lamellar α/β phases in Ti–6Al–4V to duplex (bimodal) structures as a result of TiN addition. Sintered composite held for 30 min has the highest microhardness values influenced primarily by the presence of the Ti₂N phase, while fracture morphology of the sintered alloys shows a transgranular pattern with fine dimples features which present a good cohesion and strength of the grain.