Microstructures and Properties of Solidified TiC-TiB₂ Ceramic Composites with Increasing Cr Metallic Binder Prepared by Combustion Synthesis in High-Gravity Field

Abstract:

By increasing addition amount of (CrO₃ + Al) subsystem in (B₄C + Ti) system, the solidified TiC-TiB₂ composites with a series of mass fraction of Cr binder were achieved by combustion synthesis in high-gravity field. The microstructures of the solidified ceramics presented a number of fine TiB₂ platelets embedded in TiC grains, Cr-Ti alloy or between TiC grains and Cr-Ti alloy. The increased Cr binder in the ceramic not only brought about the enhanced densification of the ceramic due to fill-up of Cr-Ti liquid in shrinkage cavities between solidified TiC and TiB₂ phases, but more importantly made fine-grained even ultrafine-grained microstructure achieved because of the accelerated nucleation and the decelerated growth of TiB₂ at initial stage of material solidification. As a result of the achievement of fine-grained even ultrafine-grained microstructure along with the enhanced toughneing mechanisms contributed by the refined TiB₂ platelets and the increased plastic phases of Cr-Ti alloy, the solifidied TiC-TiB₂ composite containing 20.7 % Cr binder presented the maximun values of 1045 ± 25 MPa and 21.5 ± 1.6 MPa • m ^0.5, simultaneously, in flexural strength and fracture toughness along with the moderate hardness of 17.5 ± 2.2 GPa.

• Periodical: Key Engineering Materials (Volumes 512-515)
• Pages: 344-349
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.512-515.344
• Online since: June 2012
• Authors: Liang Xiang Liu, Long Zhang, Zhong Min Zhao, Min Quan Wang
• Keywords: Densification, Metallic Binder, TiC-TiB₂ Composite, Ultrafine Grained Microstructure

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