Abstract This report deals with the synthesis of entropy stabilized (ES) single-phase (Hf,Nb,Ta,Ti,Zr)B2 powders, with specific surface area of about 1.6 m2/g, in a AlB2-type structure using individual transition metal (TM) oxides and, for the first time, elemental boron and carbon as precursors to feed the carbo/boro-thermal (CBT) reduction. Elemental B and C were intimately mixed into a mixture of five TM oxide powders, TM = Hf, Nb, Ta, Ti and Zr through an high energy planetary milling. ES single-phase TM diboride solid solution powders were obtained by a synthesis process consisting of a CBT reduction followed by solid solution formation. A B:C molar ratio = 1.27 (per 1 M mass of metals) was adjusted leading the CBT reduction to completion (i.e., full conversion of TM oxides), applying the synthesis temperature of 2123 K under vacuum. The micro-strain intended as deviation of some inter-planar distances of the entropy stabilized AlB2-type solid solution lattice, was analyzed by x-ray diffraction: a strong anisotropic micro-strain was found, and was attributed to the compositional disorder due to the coexistence of differing TM with different atomic radius.

中文翻译：

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通过碳/硼热还原获得的熵稳定单相 (Hf,Nb,Ta,Ti,Zr)B2 固溶体粉末

摘要 本报告涉及比表面积约为 1.6 m2/g 的熵稳定 (ES) 单相 (Hf,Nb,Ta,Ti,Zr)B2 粉末的合成，在 AlB2 型结构中使用单独的过渡金属 (TM) 氧化物，并且首次将元素硼和碳作为前体用于碳/硼热 (CBT) 还原。通过高能行星研磨将元素 B 和 C 紧密混合成五种 TM 氧化物粉末的混合物，TM = Hf、Nb、Ta、Ti 和 Zr。ES单相TM二硼化物固溶体粉末是通过由CBT还原和固溶体形成组成的合成过程获得的。AB:C 摩尔比 = 1.27（每 1 M 质量的金属），导致 CBT 还原完成（即 TM 氧化物的完全转化），在真空下应用 2123 K 的合成温度。