Mechanical properties of Al₂O₃\Ti composites fabricated by spark plasma sintering

Al₂O₃\Ti composites presenting a range of metal to ceramic ratios were fabricated using SPS technology and subsequently characterized. A titanium hydride that decomposes in the 600-700 °C temperate range was used as the source of Ti. The composite densification process was initiated at 825 °C, and reached a maximum densification rate at 1150 °C. Microstructural analysis revealed the homogenous distribution of sub-micron-sized Al₂O₃ grains and micron-sized Ti grains. Thus, the fine microstructure of the composites provided improvements in hardness, Youngs moduli and flexure strengths. The composites displayed lower resistance to fracture than did pure alumina, with cracks largely propagating around the alumina grains, which indicates that the ceramic-metal interface is weak. Finally, the formation of a Ti-Al-O solid solution at the metal/ceramic interface was detected by scanning electron microscopy and X-ray diffraction.