Micro-Raman stress imaging of ceramic (C, SiC)-fiber-reinforced ceramic-matrix and metal–matrix composites

The high strength and toughness of brittle fiber-reinforced composites result from the conservation of the pristine state of the fiber and from special fiber-matrix interphases. Raman scattering is a unique tool providing information on the structure and short-range order of amorphous, nanocrystalline or crystalline phases, as well as on the stress level, via the stress-induced wavenumber shift arising from chemical bond anharmonicity. Quantitative results can be obtained by calibrating the fiber wavenumber shift under tensile stress. Examples chosen among (C, SiC) fiber-reinforced ceramic (celsian, mullite) and intermetallic (Ti6242) matrix composites are discussed.