High-Entropy Metal Diborides: A New Class of High-Entropy Materials and a New Type of Ultrahigh Temperature Ceramics.
High-Entropy Metal Diborides: A New Class of High-Entropy Materials and a New Type of Ultrahigh Temperature Ceramics.
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DOI：
10.1038/srep37946
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发表时间：
2016-11-29
影响因子：
4.6
通讯作者：
Luo J
中科院分区：
文献类型：
--
作者：
Gild J;Zhang Y;Harrington T;Jiang S;Hu T;Quinn MC;Mellor WM;Zhou N;Vecchio K;Luo J
通过高能球磨和放电等离子烧结制备了七种等摩尔五组分金属二硼化物。其中6人，包括（Hf0.2Zr0.2Ta0.2Nb0.2Ti0.2）B2，（Hf0.2Zr0.2Ta0.2Mo0.2Ti0.2）B2，（Hf0.2Zr0.2Mo0.2Nb0.2Ti0.2）B2，（Hf0.2Mo0.2Ta0.2Nb0.2Ti0.2）B2、（Mo0.2Zr0.2Ta0.2Nb0.2Ti0.2）B2和（Hf0.2Zr0.2Ta0.2Cr0.2Ti0.2）B2实际上具有六方AlB 2结构的一个固溶硼化物相。修正的休谟-罗瑟里尺寸差因子被用来合理化这些金属二硼化物中高熵固溶体的形成。大于92%的理论密度通常已经实现了从纳米级到微米级的基本上均匀的组成。畸变校正扫描透射电子显微镜（AC STEM），高角度环形暗场和环形亮场（HAADF和ABF）成像和纳米级成分映射，已进行确认形成的2-D高熵金属层，由刚性2-D硼网，没有任何可检测的分层偏析沿着c轴。这些材料代表了一种新型的超高温陶瓷（UHTCs）以及一类新的高熵材料，它不仅是第一个高熵非氧化物陶瓷（硼化物）制造，但也具有独特的非立方（六方）和层状（准2D）的高熵晶体结构，显着不同于所有在先前的研究报告。初步性能评估表明，这些高熵金属二硼化物的硬度和抗氧化性通常高于/优于通过相同制造工艺制成的五种单独金属二硼化物的平均性能。
Seven equimolar, five-component, metal diborides were fabricated via high-energy ball milling and spark plasma sintering. Six of them, including (Hf0.2Zr0.2Ta0.2Nb0.2Ti0.2)B2, (Hf0.2Zr0.2Ta0.2Mo0.2Ti0.2)B2, (Hf0.2Zr0.2Mo0.2Nb0.2Ti0.2)B2, (Hf0.2Mo0.2Ta0.2Nb0.2Ti0.2)B2, (Mo0.2Zr0.2Ta0.2Nb0.2Ti0.2)B2, and (Hf0.2Zr0.2Ta0.2Cr0.2Ti0.2)B2, possess virtually one solid-solution boride phase of the hexagonal AlB2 structure. Revised Hume-Rothery size-difference factors are used to rationalize the formation of high-entropy solid solutions in these metal diborides. Greater than 92% of the theoretical densities have been generally achieved with largely uniform compositions from nanoscale to microscale. Aberration-corrected scanning transmission electron microscopy (AC STEM), with high-angle annular dark-field and annular bright-field (HAADF and ABF) imaging and nanoscale compositional mapping, has been conducted to confirm the formation of 2-D high-entropy metal layers, separated by rigid 2-D boron nets, without any detectable layered segregation along the c-axis. These materials represent a new type of ultra-high temperature ceramics (UHTCs) as well as a new class of high-entropy materials, which not only exemplify the first high-entropy non-oxide ceramics (borides) fabricated but also possess a unique non-cubic (hexagonal) and layered (quasi-2D) high-entropy crystal structure that markedly differs from all those reported in prior studies. Initial property assessments show that both the hardness and the oxidation resistance of these high-entropy metal diborides are generally higher/better than the average performances of five individual metal diborides made by identical fabrication processing.
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影响因子：
16.6
作者：
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影响因子：
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