Crystal Growth, Fracture Behavior and Toughening of Rapidly-Solidified TiC-TiB₂ Prepared by Combustion Synthesis in High-Gravity Field

Abstract:

Micro-nanocrystalline microstructures characterized by TiB₂ platelets of the average thickness close to or smaller than 1 μm, were achieved in full-density solidified TiC-TiB₂ composites by combustion synthesis in high-gravity field. XRD, FESEM and EDS results showed that a large number of fine TiB₂ platelets were uniformly embedded in irregular TiC grains, a few Cr-Al metallic phases or in between those phases. The achievement of micro-nanocrystalline microstructures results from low-velocity faceting growth of TiB₂ crystal, high-velocity non-faceting growth of TiC solid and high diffusion rate of C relative to B in liquid TiC-TiB₂. The relative density, Vickers hardness, flexural strength and fracture toughness of TiC-TiB₂ composites measured 99.3%, 21.5 ± 1.5 GPa, 845 ± 35 GPa and 16.8 ± 1.5 MP • m^0.5, respectively. High flexural strength of the materials benefits mainly from the achievement of micro-nanocrystalline microstructure in the full-density solidified ceramic and high fracture toughness contributed from intensive coupled toughening mechanisms by a large number of fine TiB₂ platelets and a few Cr-Al metallic phases.

• Periodical: Key Engineering Materials (Volumes 512-515)
• Pages: 691-696
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.512-515.691
• Online since: June 2012
• Authors: Zhong Min Zhao, Long Zhang, Yi Gang Song, Wei Guo Wang, Jian Qiang He
• Keywords: Crystal Growth, Fracture Behavior, TiC-TiB₂ Composite, Toughening

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