Microstructural evolution and mechanical properties of pure titanium powders processed by spark plasma sintering

In this study the effect of sintering pressure on the densification, microstructure and mechanical properties of commercial pure titanium (CP-Ti) powders with varying chemistry was investigated. The sintering was performed at a constant dwell time of 3 min at varying temperature and pressure in the range of 550–900 °C and 25-75 MPa in vacuum, respectively. Full densification with high Vickers hardness values of 340 HV and 262 HV was obtained at 25 MPa at 800 °C and 900 °C respectively for two commercial powders with different average particles sizes. Different microstructural transformations with respect to increasing temperature and pressure were observed on the sintered pellets. The results were discussed emphasizing the huge role of the interstitial elements, contained in the starting powders, on the properties (relative density, Vickers hardness and microstructure) of the dense samples. This paper shows that good mechanical properties can be obtained by SPS technique when CP-Ti powders are sintered at very low temperature during a short period in contrast to conventional fabrication techniques.