Journal
ACTA MATERIALIA
Volume 57, Issue 9, Pages 2765-2774Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.actamat.2009.02.027
Keywords
Carbides; TEM; High temperature; Mechanical property; Thermal property
Funding
- National Outstanding Young Scientist Foundation [59925208, 50125204]
- Natural Science Foundation of China [90403027, 50832008]
- Hundred-Talent Plan program of Chinese Academy of Sciences
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A Hf-Al-C composite composed of Hf3Al3C5, Hf2Al4C5 and Hf3Al4C6 has been successfully synthesized by a hot pressing method; its microstructure and mechanical and thermal properties were systematically characterized. Hf-Al-C composite conserves the high hardness and stiffness similar to HfC. Interestingly, the composite exhibits Much higher strength and fracture toughness than HfC due to its fine and anisotropic grains. Diffusion-accommodated grain-boundary sliding of Hf-Al-C ceramics at high temperature is inhibited by glass-free grain boundaries and tight interlocking of grains at grain-edge triple junctions, resulting in high remaining stiffness up to 1600 degrees C. Dislocations on the basal planes of Hf-Al-C ceramics with a Burgers vector of 1/3 < 11 (2) over bar0 > can be activated at high temperature. Hf-Al-C composite shows higher coefficient of thermal expansion and specific heat capacity as well as lower thermal conductivity than HfC. The superior mechanical and thermal properties make Hf-Al-C compounds good high-temperature structural materials. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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