Densification, microstructure, and nanomechanical evaluation of pulsed electric sintered zirconia-silicon nitride reinforced Ti-6Al-4 V alloy
Anthony O. Ogunmefun, Peter Apata Olubambi, Bamidele Lawrence Bayode, Ufoma Silas Anamu, Emmanuel Olorundaisi, Olusoji Oluremi Ayodele, Bukola Joseph Babalola, Sindile Mkhatshwa, Peter Ifeolu Odetola, Kibambe Ngeleshi
Abstract
Abstract In this study, the influence of silicon nitride (Si 3 N 4 ) and zirconia (ZrO 2 ) ceramics was examined on the titanium alloy using the pulsed electric current sintering technique to investigate the microstructural behavior, densification, and nanomechanical properties of these composites. Si 3 N 4 and ZrO 2 were dispersed in Ti-6Al-4 V at a functional pressure of 50 MPa, a sintering temperature of 1200 °C, a heating rate of 100 °C/min, and a holding time of 10 min. The ternary composite samples were prepared viz, Cs1 (Ti6Al4V- 3 vol.% Si 3 N 4 - 15 vol.% ZrO 2 ), Cs2 (Ti6Al4V- 3 vol.% Si 3 N 4 - 10 vol.% ZrO 2 ), and Cs3 (Ti6Al4V- 3 vol.% Si 3 N 4 - 5 vol.% ZrO 2 ). The bulk morphology of the composites was studied using scanning electron microscopy (SEM) equipped with EDS, and the phase contents were identified with an X-ray diffractometer (XRD). The relative density results for the tri-composites showed that the Cs1 sample recorded the highest at 99.94%, producing a fully dense sintered composite. However, there was a drop in the relative density of composites Cs2 and Cs3, recording 97.73% and 97.11%, respectively, comparable to the unreinforced Ti-6Al-4 V alloy with 98.65%. The nanoindentation examination conducted for the trio-composites showed linear mechanical responses/improvement, with Vickers hardness, from 589.31 to 865.70 MPa; nano hardness, from 6.466 to 9.441 GPa, and elastic modulus, from 113.52 to 185.95 GPa.