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

Ti-6Al-4V and Ti-6Al-4V-Si3N4-TiN powders were consolidated through spark plasma sintering process at 1000 degrees C and varying ceramic additions of 2.5 wt%Si3N4-2.5 wt%TiN, 5 wt%Si3N4-5wt%TiN and 7.5 wt%Si3N4-7.5wt%TiN. The effect of varying ceramic additions on the densification and microstructure was evaluated. The experiments were executed at a temperature of 1000 degrees 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. (C) 2018 Elsevier B.V. All rights reserved.