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Keywords:

  • alumina;
  • zirconia;
  • composites;
  • microstructure;
  • mechanical properties

Composites of Al2O3 (A) and cubic ZrO2 (Z) (8 mol% Y2O3) (with c-ZrO2 volume fractions ranging from O to 1) were fabricated by pressureless sintering of mechanically mixed powders. The microstructures of the AZ composites were duplex, with the grains of both phases exhibiting similar size. Room-temperature mechanical properties including Young's modulus (determined from elastic wave velocity measurements), strength and toughness (by indentation-strength-in-bending), and Vickers microhardness were evaluated for the full range of compositions. All properties exhibited a linear decrease with increasing c-ZrO2 content, and no R-curve behavior was seen in any of the composite compositions. Fracture morphology, observed from cracks emanating from microhardness indentations, changed from essentially intergranular for the tougher Al2O3 to transgranular for c-ZrO2, with AZ composites exhibiting mixed morphology.