Effect of oxidation time on microstructure and mechanical properties of C.sub.f/SiC-Al composites after high-temperature oxidation

The microstructure and elemental composition evolution of C.sub.f/SiC-Al composites prepared by combined precursor infiltration pyrolysis (PIP) and vacuum-pressure infiltration processes after high-temperature oxidation for different times was investigated. Meanwhile, the mechanical properties of the composites after oxidation treatment were characterized by nanoindentation and compressive performance tests. The results show that when the oxidation temperature was 400 °C and above, the weight loss rate of the composites gradually increased with the prolongation of the oxidation time, and the interface separation between the carbon fiber and SiC matrix became more obvious. Moreover, the nanoindentation elastic modulus of the Al alloy matrix and the SiC matrix decreased significantly with the increase in oxidation time, while the nanoindentation hardness of the aluminum alloy hardly changed. After oxidizing at 400 °C for 7 h, the in-plane compressive strength of the composites reached the maximum (584.7 MPa), and after oxidizing at 500 °C for 9 h, the compressive strength decreased to the minimum (347.8 MPa).