Fabrication of a new SiC/2024Al co-continuous composite with lamellar microstructure and high mechanical properties

Abstract

New SiC/2024Al co-continuous composites with lamellar microstructure have been successfully fabricated via squeezing molten 2024Al alloy into porous SiC preforms produced by freeze casting. During the process, the porosity and microstructure of porous SiC preforms was well controlled by initial solid loading and freezing temperature, consequently, the content and architecture of ceramic reinforcement in the final co-continuous composites was precisely tailored. The microstructure and mechanical properties of the prepared composites were studied, and the effects of initial solid loading and freezing temperature on the microstructure and mechanical properties for the final composites were investigated. The results showed that these new co-continuous composites exhibit lamellar microstructure composed of alternating ceramic and metallic lamellar. They possess high flexural strength, fracture toughness and hardness due to few defects, lamellar microstructure and well bonded interfaces between the metal and ceramic phase, with the highest strength and toughness of 931.3 MPa and 18.8 MPa m1/2 respectively in the direction parallel to the freezing direction.