Strength of Single-Phase High-Entropy Carbide Ceramics Up to 2300°C
The mechanical properties of single-phase (Hf,Zr,Ti,Ta,Nb)C high-entropy carbide (HEC) ceramics were investigated. Ceramics with relative density > 99% and an average grain size of 0.9 ± 0.3 µm were produced by a two-step process that involved carbothermal reduction at 1600°C and hot pressing at 1900°C. At room temperature, Vickers hardness was 25.0 ± 1.0 GPa at a load of 4.9 N, Young's modulus was 450 GPa, chevron notch fracture toughness was 3.5 ± 0.3 MPa·m1/2, and four-point flexural strength was 421 ± 27 MPa. With increasing temperature, flexural strength stayed above ~400 MPa up to 1800°C, then decreased nearly linearly to 318 ± 21 MPa at 2000°C and to 93 ± 10 MPa at 2300°C. No significant changes in relative density or average grain size were noted after testing at elevated temperatures. The degradation of flexural strength above 1800°C was attributed to a decrease in dislocation density that was accompanied by an increase in dislocation motion. These are the first reported flexural strengths of HEC ceramics at elevated temperatures.
L. Feng et al., "Strength of Single-Phase High-Entropy Carbide Ceramics Up to 2300°C," Journal of the American Ceramic Society, vol. 104, no. 1, pp. 419 - 427, Wiley, Jan 2021.
The definitive version is available at https://doi.org/10.1111/jace.17443
Materials Science and Engineering
Keywords and Phrases
Dislocation; High-Entropy Carbides; High-Temperature Flexural Strength; Mechanical Properties; Microstructure
International Standard Serial Number (ISSN)
Article - Journal
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01 Jan 2021