Microstructures and Toughening of TiC-TiB2Ceramic Composites with Cr-Based Alloy Phase Prepared by Combustion Synthesis in High-Gravity Field

摘要

Micro-nanocrystalline microstructures which are characterized by TiB2platelets of the average thickness close to or smaller than 1 μm can be achieved in nearly full-density solidified TiC-TiB2ceramic composites with Cr-based alloy phases by combustion synthesis in ultra-high gravity field of 2500 g. The filler phases in ceramic composites are actually Cr-based alloy with a little solidified solution of Ni atoms and Al atoms. The hardness, flexural strength, and fracture toughness of the materials are 18.5 ± 1.5 GPa, 650 ± 35 MPa, and 16.5 ± 1.5 MPa⋅m0.5, respectively. The improved fracture toughness of TiC-TiB2ceramic composites results from crack deflection, crack bridging, and pull-out by a large number of fine TiB2platelets and plastic deformation with some Cr-based alloy phases.