Processing–microstructure–property relationships in short-fiber Nextel™ 610/Al₂O₃ composites

Ceramic matrix composites (CMCs) are increasingly investigated and considered for thermostructural applications thanks to their excellent thermal stability and their highly specific properties. All-oxide CMCs offer high oxidation resistance at temperature approaching 1,000 °C compared to metal alloy or non-oxide CMCs. However, the manufacturing of small or/and complex CMC parts remains difficult to implement at industrial scale. In this study, Al 2 O 3 short fiber-reinforced Al 2 O 3 matrices were fabricated by pressureless-sintering (PS), hot-pressing (HP), and spark-plasma-sintering (SPS). Results revealed that, at 1,200 °C, the applied pressure enhances significantly the matrix density and leads to brittle mechanical behavior. Although the pressureless sintering leads to lower densification rates, weak interfaces are observed, leading to damage-tolerant behavior. Using lower spark plasma sintering temperature allows to produce fine and homogeneous alumina microstructure with lower density. A temperature of 1,100 °C avoids strong interfacial bonding and promotes damage tolerant response with a higher maximum strength.