Toughening mechanisms of Ti3SiC2- and TiB2- toughened SiC matrix prepared via reactive melt infiltration

Abstract

The SiC-Ti 3 SiC 2 -TiB 2 composites herein were prepared in situ by reactive melt infiltration (RMI). The synergy mechanism between Ti 3 SiC 2 and TiB 2 on fracture toughness of SiC matrix was investigated. The phase composition and microstructure of SiC-Ti 3 SiC 2 -TiB 2 composites were studied, and their mechanical properties, such as Vickers hardness, elastic modulus and indent fracture toughness, were compared to those of SiC ceramics and SiC-Ti 3 SiC 2 composites. The crack propagation of SiC-Ti 3 SiC 2 -TiB 2 composites was simulated via Extended Finite Element Method (XFEM), and the fracture behavior in laminated Ti 3 SiC 2 grains was also evaluated. The results show that SiC-Ti 3 SiC 2 -TiB 2 composites exhibit an indentation fracture toughness of 9.57 MPa m 1/2 , which is greatly higher than that of SiC ceramics and SiC-Ti 3 SiC 2 composites. It was suggested that the main toughening mechanisms of lamellar Ti 3 SiC 2 grains and columnar TiB 2 grains are crack deflection, crack bridging, grain fracture, delamination and grain pull-out.

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