Fabrication of PSZ–Ti composites by spark plasma sintering and their mechanical properties

In this investigation, PSZ–Ti composites with various volume ratios of partially stabilized zirconia (PSZ) and pure titanium (Ti) were fabricated by spark plasma sintering (SPS) technique, and their mechanical properties were evaluated. The relative density of the composites by SPS was about 93% for pure PSZ and increased up to almost 100% with increasing Ti content. For the composites, reaction phases were examined by the X-ray diffraction (XRD) analysis, and the Vickers hardness, Young׳s modulus, bending strength and fracture toughness were evaluated. According to the XRD analysis, Ti₂O and Ti₂ZrO were detected on all composites and pure Ti was detected on the composites with Ti volume fraction more than 90%. The Vickers hardness and Young׳s modulus were higher than predictions by the rule of mixture. The bending strength and fracture toughness of the composites decreased up to 75%Ti and then increased from 75%Ti to 100%Ti with increasing Ti content. It was suggested that these results were caused by hardening and embrittlement due to the reaction phases such as Ti₂O and Ti₂ZrO.