Microstructures and mechanical properties of in-situ SiC-TiB2 ceramic composites fabricated by reactive melt infiltration

Abstract

Abstract An in situ SiC-TiB2 ceramic composites was fabricated by infiltrating the Al-Si alloy melt into pre-sintered porous preforms with different B4C/TiC weight ratios. The phase composition and microstructure of the SiC-TiB2 ceramic composites were analyzed to understand the synthesis mechanism of the composites. TiB2 and SiC were originated from the reaction among B4C, TiC and Al-Si melt. When the B4C/TiC weight ratio was 35:65, the fabricated TiB2-SiC ceramic composites but no byproduct or raw powders displayed the optimal microstructure, and the TiB2 and SiC particles were homogeneously distributed in Al-Si melt. The SiC-TiB2 ceramic composites with the optimal microstructure owned the outstanding integrated mechanical properties: flexural strength of 245 MPa, fracture toughness of 4.32 MPa m1/2 and Vickers hardness of 10.46 GPa. The fracture surface of SiC-TiB2 ceramic composites showed the mixed fracture mode with intergranular and transgranular fracture. The strengthening and toughening mechanisms were investigated from particle reinforcement, pulling out of grains and crack deflection found in the SiC-TiB2 ceramic composites.