High‐Temperature Mechanical Behavior of Fiber‐Reinforced Glass‐Ceramic‐Matrix Composites

Lithium aluminosilicate glass‐ceramic‐matrix composites reinforced with Sic fibers were tested at 900° and 1000°C in flexural and tensile configurations. The composites showed severe thermomechanical degradation when tested in oxidizing atmospheres. This degradation was found to depend on oxygen partial pressure. For P _{o 2} ≳10 ³ Pa the composites failed in a brittle fashion; a single crack initiated and propagated through the matrix and fibers. At lower P _o2 , multiple matrix cracking was observed, and the fibers bridged the matrix cracks.