Alumina matrix was prepared with varying amounts of metal molybdenum particles of two different grain sizes. R-curves were determined during stable crack propagation and a piezo-spectroscopic technique was used to assess the bridging stresses developed along the crack wake (at the metal/matrix interface) at the critical condition for crack propagation. In both kinds of composites, the toughness monotonically increases with the amount of molybdenum added. In addition, bridging stress and therefore toughness were higher when coarser particles were present. The theoretical R-curves calculated from the discrete (microscopic) bridging stress distribution obtained by in situ Raman spectroscopy were in good agreement with the experimental data. [S0094-4289(00)02003-X]

Issue Section:
Technical Papers
Keywords:
molybdenum, alumina, grain size, particle reinforced composites, Raman spectra, fracture toughness, cracks, composite material interfaces
Topics:
Composite materials, Crack propagation, Fracture (Materials), Fracture toughness, Grain size, Metals, Molybdenum, Particulate matter, Stress, Ceramic matrix composites, Wakes, Fracture mechanics
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