Spark plasma sintered Ti-6Al-4V-Si3N4-TiN ternary composites: Effect of combined microsized Si3N4 and TiN addition on microstructure and mechanical properties for aerospace application

Highlights: • Ti-6Al-4V-(Si₃N₄+xTiN) composites were synthesized by spark plasma sintering. • The microstructures of the composites consisted of lamellar and bimodal structures. • Spark plasma sintered Ti-6Al-4V consolidated with Si₃N₄+TiN particulates shows high hardness and wear resistance properties. • The composites fabricated with 5 wt%.Si3N4+5 wt%.TiN exhibits the highest hardness value of 727.41 HV. Ti-6Al-4V and Ti-6Al-4V-Si₃N₄-TiN powders were consolidated through spark plasma sintering process at 1000 ^° C and varying ceramic additions of 2.5 wt%Si₃N₄-2.5 wt%TiN, 5 wt%Si₃N₄-5wt%TiN and 7.5 wt%Si₃N₄-7.5 wt%TiN. The effect of varying ceramic additions on the densification and microstructure was evaluated. The experiments were executed at a temperature of 1000 °C with a holding time of 6 min under a pressure of 50Mpa. Ti-6Al-4V-Si₃N₄-TiN powders were premixed with different weight proportions of Si₃N₄ and TiN powders. Spark plasma sintered composite samples were created from the combination and the influence of Si₃N₄ and TiN on the microstructure and mechanical properties of the composites were explored. Scanning electron microscope attached to an energy dispersive spectroscopy (SEM-EDS) was used to study the bulk morphology of the sintered composites. The phases present in the fabricated sintered composites were observed by X-ray diffraction spectrometer (XRD). Microhardness was studied by the means of high impact diamond Dura scan micros hardness tester. Electrochemical behavior of the sintered samples was measured in a 3.65% NaCl solution containing 0.1 M HCl by potentiodynamic polarization method. The experimental results revealed that the microstructure, hardness and corrosion resistance properties of the material were improved by the addition of Si₃N₄ and TiN. The effect of Si₃N₄ and TiN on the performance characteristics of Ti-6Al-4V alloy was seen to be compactable and beneficial for aerospace application.