Properties Improvement of Spark Plasma Sintered Ti-7Al-1Mo Ternary Alloy by TiN Nanoparticles Addition

Abstract

Titanium (Ti) alloys are materials of interest in structural and chemical applications due to their low density, outstanding mechanical and chemical resistance properties. However, the mechanical properties still need to be enhanced to make them suitable as a replacement for Ni-based superalloys. There have been significant breakthroughs in the reinforcement of Ti alloy with a small weight percentage (wt.%) of ceramics. This work investigates the effect of TiN nanoparticles’ addition on the densification, phase transformation, microstructure, hardness, and compressive properties of Ti-7Al-1Mo ternary alloy. 3 wt.% of TiN nanoparticles was blended with Ti-7Al-1Mo powder, and the resulting admixed powder was consolidated via spark plasma sintering technique at 50 MPa pressure, 10 min holding time, and 1000 °C temperature. Scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry were used to characterise the microstructure and phase composition respectively. The microstructure of Ti-7Al-1Mo revealed a lamellar structure with alpha (α) phase and minor beta (β) phase with visible grain boundaries, while TiN reinforced Ti-7Al-1Mo composite microstructure shows a bimodal structure with reduction in the lamellar structure. Ti-7Al-1Mo ternary alloy has a hardness value of 352±17 HV0.1 and a compressive yield strength of 985±31 MPa. The composite shows an increment of 74 HV and 323 MPa in its hardness and compressive yield strength respectively in comparison to the ternary alloy.