Bulk High-Entropy Hexaborides

For the first time, a group of CaB6-typed cubic rare earth high-entropy hexaborides have been successfully fabricated into dense bulk pellets (>98.5% in relative densities). The specimens are prepared from elemental precursors via in-situ metal-boron reactive spark plasma sintering. The sintered...

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Bibliographic Details
Published in:arXiv.org 2021-04
Main Authors: Qin, Mingde, Qizhang Yan, Liu, Yi, Wang, Haoren, Wang, Chunyang, Lei, Tianjiao, Vecchio, Kenneth S, Xin, Huolin L, Rupert, Timothy J, Luo, Jian
Format: Article
Language:English
Subjects:
Bulk density
Diamond pyramid hardness
Entropy
Modulus of elasticity
Nanoindentation
Pellets
Photoelectrons
Plasma sintering
Spark plasma sintering
Work functions
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Summary:For the first time, a group of CaB6-typed cubic rare earth high-entropy hexaborides have been successfully fabricated into dense bulk pellets (>98.5% in relative densities). The specimens are prepared from elemental precursors via in-situ metal-boron reactive spark plasma sintering. The sintered bulk pellets are determined to be single-phase without any detectable oxides or other secondary phases. The homogenous elemental distributions have been confirmed at both microscale and nanoscale. The Vickers microhardness are measured to be 16-18 GPa at a standard indentation load of 9.8 N. The nanoindentation hardness and Young's moduli have been measured to be 19-22 GPa and 190-250 GPa, respectively, by nanoindentation test using a maximum load of 500 mN. The material work functions are determined to be 3.7-4.0 eV by ultraviolet photoelectron spectroscopy characterizations, which are significantly higher than that of LaB6.
ISSN:2331-8422