Abstract
Fibrous monolithic ceramics were fabricated in the alumina/nickel system. The microstructure consists of high‐aspect‐ratio polycrystalline cells of alumina separated by thin cell boundaries of nickel. The nickel content in the material is 3 to 8 vol%. The fibrous monolith with uniaxially aligned cells fails noncatastrophically in flexure. Bridging ligaments of nickel, crack deflection along cell boundaries, and crack branching in the axial direction are observed in flexure bars and notched beams. Strength values range from 246 to 375 MPa. Indentations cause controlled damage on the surface but do not introduce strength‐degrading flaws. The alumina/nickel fibrous monoliths also show potential for use at high temperatures in oxidizing environments. Noncatastrophic fracture behavior is observed at room temperature after 10 h at 1200°C in air. The Ni cell boundary network is oxidized to a depth of 50 to 100 μm by this heat treatment. The NiO oxidation product in the cell boundaries reacts partly with alumina from the cells to form NiAI2O4, which would provide better protection.
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