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Microstructure of (Hf-Ta-Zr-Nb)C high-entropy carbide at micro and nano/atomic level
Journal of the European Ceramic Society ( IF 5.7 ) Pub Date : 2018-05-09 , DOI: 10.1016/j.jeurceramsoc.2018.05.006
Ján Dusza , Peter Švec , Vladimír Girman , Richard Sedlák , Elinor G. Castle , Tamás Csanádi , Alexandra Kovalčíková , Michael J. Reece

A High Entropy (Hf-Ta-Zr-Nb)C Ultra-High Temperature Ceramic (UHTC) was fabricated by ball milling and Spark Plasma Sintering (SPS) with a density of 99%. The microstructure characteristics were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) in combination with electron back scattered diffraction (EBSD) and transmission electron microscopy (TEM). Atomic structure and local chemical disorder was determined by means of scanning transmission electron microscopy (STEM) in conjunction with energy dispersive X-ray spectroscopy (EDS). According to the results, high purity, dense and homogeneous high entropy carbide with Fm-3 m crystal structure was successfully produced. The grain size ranged from approximately 5 μm to 25 μm with average grain size of 12 μm. Chemical analyses proved that all grains had the same chemical composition at the micro as well as on the nano/atomic level without any detectable segregation. The approximately 1.5 nm thin amorphous grain boundary phase contained impurities that came from the starting powders and the ball milling process.



中文翻译:

(Hf-Ta-Zr-Nb)C高熵碳化物的微观和纳米/原子级微观结构

通过球磨和等离子烧结(SPS)制备了密度为99%的高熵(Hf-Ta-Zr-Nb)C超高温陶瓷(UHTC)。使用X射线衍射(XRD),扫描电子显微镜(SEM)结合电子背散射衍射(EBSD)和透射电子显微镜(TEM)研究了微结构特征。通过扫描透射电子显微镜(STEM)结合能量色散X射线光谱(EDS)来确定原子结构和局部化学异常。根据该结果,成功地制造了具有Fm-3m晶体结构的高纯度,致密且均质的高熵碳化物。晶粒尺寸为约5μm至25μm,平均晶粒尺寸为12μm。化学分析证明,所有晶粒在微观以及纳米/原子水平上都具有相同的化学组成,而没有任何可检测到的偏析。约1.5 nm的薄非晶态晶界相包含杂质,这些杂质来自起始粉末和球磨工艺。

更新日期:2018-05-09
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