High-entropy (HfTaTiNbZr)C and (HfTaTiNbMo)C carbides fabricated through reactive high-energy ball milling and spark plasma sintering |
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Affiliation: | 1. National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan;2. WPI-Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan;3. Department of Materials Science and Engineering, Tohoku University, 6-6-02 Aramaki Aza Aoba, Sendai 980-8579, Japan |
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Abstract: | Powders of high-entropy Hf0.2Ta0.2Ti0.2Nb0.2Zr0.2C (HECZr) and Hf0.2Ta0.2Ti0.2Nb0.2Mo0.2C (HECMo) carbides were fabricated through the reactive high-energy ball milling (R-HEBM) of metal and graphite particles. It was found that 60 min of R-HEBM is adequate to achieve a full conversion of the initial precursors into a FCC solid solution for both compositions. The HECZr powder possesses a unimodal particle size distribution (40% d ≤ 1 μm, 95% d ≤ 10 μm), and the HECMo powder features a bimodal distribution with a slightly larger particle size overall (30% d ≤ 1 μm, 80% d ≤ 10 μm). Bulk high-entropy ceramics with a minor presence of an oxide phase were fabricated through the spark plasma sintering of these high-entropy powders at 2000 °C with a 10 min dwelling time. The HECZr ceramics possess a relative density of up to 94.8%, hardness of 25.7 ± 3.5 GPa, Young's modulus of 473 ± 37 GPa, and thermal conductivity of 5.6 ± 0.1 W/m·K. HECMo ceramics with a relative density of up to 93.8%, hardness of 23.8 ± 2.7 GPa, Young's modulus of 544 ± 48 GPa, and thermal conductivity of 5.9 ± 0.2 W/m·K were also fabricated. A comparison of the properties of the HECs produced in this study and those previously reported is also provided. |
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Keywords: | High-entropy ceramic Carbides High-energy ball milling Mechanochemical synthesis Spark plasma sintering |
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