Influence of sintering temperature on densification, microstructure and mechanical properties of Ti-6Ni alloy developed via spark plasma sintering

Abstract

Abstract Titanium is used extensively in various engineering applications as a result of its unique physical, chemical and mechanical properties. However, the difficulty encountered in fabricating a fully densified titanium sample informed the introduction of alloying elements into the matrix in order to form a liquid phase and enhance sinterability. This work explored the influence of sintering temperature on the densification, microstructure and mechanical properties of Ti-6Ni alloy developed via spark plasma sintering at varying temperature from 850 °C to 1200 °C in a vacuum, under isothermal holding time, heating rate and applied pressure of 10 min, 100 °C/min and 50 MPa respectively. Characterization of the mixed powder and bulk sintered sample were carried out with the aid of scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscope (EDS) and X-ray diffraction (XRD). Relative density and hardness of the samples were determined following the Archimedes and Vickers method respectively. The SEM results indicated the presence of multiple phases in the microstructure of the sintered samples. These phases were confirmed by the EDS and XRD analysis results, as the intermetallics of Ti-Ni. Densifications above 98%, was achieved and the hardness values were found to vary with the densification of the sintered alloy, across the investigated sintering temperatures.