Toughening of ZrB2-SiC ceramics with the microstructure ZrB2/Zr-Al-C fibrous monolith

A ZrB2-20 vol.% SiC-30 vol.% Zr-Al-C ceramic was fabricated by hot pressing at 1900 degrees C and 30 MPa for 1 h in vacuum. The ZrB2-SiC/Zr-Al-C ceramic showed an excellent fracture toughness of 5.4 +/- 0.4 MPa m(1/2) due to its ZrB2/Zr-Al-C fibrous monolith microstructure and the in situ formed layered Zr-Al-C grains, which could enhance crack deflection, crack bridging and crack branching. In addition, the weaker interface bonding and weaker internal layers existed within the Zr-Al-C crystal. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.