The Microstructure Evolution Process and Flexural Behaviours of SiC Matrix Ceramic Infiltrated by Aluminium Base Alloy

In this paper, an infiltration approach was proposed to generate a Ti3Si(Al)C-2 transition layer in SiC matrix composites to effectually strengthen SiC ceramics. The infiltration temperature played a significant role in the evolution of the microstructure, phase composition, and flexural behaviours. Molten aluminium base alloy fully penetrated SiC ceramic after infiltration at different experimental temperatures (800-1000 degrees C). The phases in the reaction layer on the surface of SiC ceramic samples varied with the infiltration temperature. When infiltrated at 800 degrees C, only SiC and Al phases can be found in SiC composites, whereas at 900 degrees C, a reaction layer containing Ti3Si(Al)C-2 and SiC was produced. The Ti3Si(Al)C-2 phase grew in situ on SiC. At 1000 degrees C, the Ti3Si(Al)C-2 phase was unstable and decomposed into TiC and Ti5Si3. The cermet phase Ti3Si(Al)C-2 was synthesized at a relatively low temperature. Consequently, the flexural modulus and three-point bending strength of samples infiltrated at 900 degrees C was enhanced by 1.4 and 2.4 times for the original SiC ceramic, respectively.