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

An in situ SiC-TiB 2 ceramic composites was fabricated by infiltrating the Al-Si alloy melt into pre-sintered porous preforms with different B 4 C/TiC weight ratios. The phase composition and microstructure of the SiC-TiB 2 ceramic composites were analyzed to understand the synthesis mechanism of the composites. TiB 2 and SiC were originated from the reaction among B 4 C, TiC and Al-Si melt. When the B 4 C/TiC weight ratio was 35:65, the fabricated TiB 2 -SiC ceramic composites but no byproduct or raw powders displayed the optimal microstructure, and the TiB 2 and SiC particles were homogeneously distributed in Al-Si melt. The SiC-TiB 2 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-TiB 2 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-TiB 2 ceramic composites. • SiC-TiB 2 ceramic composite was creatively fabricated by RMI method through infiltrating Al-Si melt into pre-sintered porous TiC-B 4 C preform. • The optimal mechanical properties of SiC-TiB 2 ceramic composite was obtained when the weight ratio of B 4 C/TiC raw powder was 35:65. • The synthesis mechanism and fracture mode of the as-processed SiC-TiB 2 ceramic composite were discussed. [ABSTRACT FROM AUTHOR]