Fabrication and characterization of titanium-nickel-zirconia matrix composites prepared by spark plasma sintering

Ti–Ni–ZrO₂ composites were prepared by spark plasma sintering (SPS). The effect of ZrO₂ content on the densification, microstructure and microhardness properties of the composites were investigated. Samples were characterized by SEM, EDS and XRD analyses. Noticeably, SPS process under the sintering conditions was achieved at a sintering temperature of 950 °C, for 10 min holding time, at 100 °C/min of heating rate and at an applied pressure of 50 MPa. This resulted in maximum densification of the powder compact and the formation of a distinguishable spherical globules rich in Ni surrounding the retained Ti. Gradient composition distribution of ZrO₂ at the grain boundaries resulted into pinning effect of the grain growth. As the ZrO₂ content increased from 5 to 10 vol%, it was accompanied by a significant increase in hardness values of the sintered composites from 480 to 713 HV.