Title

Hexagonal OsB2: Sintering, microstructure and mechanical properties

Authors

Authors

Z. L. Xie; M. Lugovy; N. Orlovskaya; T. Graule; J. Kuebler; M. Mueller; H. L. Gao; M. Radovic;D. A. Cullen

Comments

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Abbreviated Journal Title

J. Alloy. Compd.

Keywords

Osmium diboride; Mechanical properties; Nanoindentation; Ceramic; SUPERHARD RHENIUM DIBORIDE; OSMIUM DIBORIDE; ELECTRONIC-STRUCTURE; SINGLE-CRYSTALS; METAL BORIDES; HARD MATERIAL; ZIRCONIUM; 1ST-PRINCIPLES; PRESSURE; BORON; Chemistry, Physical; Materials Science, Multidisciplinary; Metallurgy &; Metallurgical Engineering

Abstract

The metastable high pressure ReB2-type hexagonal OsB2 bulk ceramics was produced by spark plasma sintering. The phase composition, microstructure, and mechanical behavior of the sintered OsB2 were studied by X-ray diffraction, optical microscopy, TEM, SEM, EDS, and nanoindentation. The produced ceramics was rather porous and contained a mixture of hexagonal (similar to 80 wt.%) and orthorhombic (similar to 20 wt.%) phases as identified by X-ray diffraction and EBSD analysis. Two boron-rich phases, which do not contain Os, were also identified by TEM and SEM/EDS analysis. Nanoindentation measurements yielded a hardness of 31 +/- 9 GPa and Young's modulus of 574 +/- 112 GPa, indicating that the material is rather hard and very stiff; however, it is very prone to crack formation and propagation, which is indicative of a very brittle nature of this material. Improvements in the sintering regime are required in order to produce dense, homogeneous and single phase hexagonal OsB2 bulk ceramics. (C) 2015 Elsevier B.V. All rights reserved.

Journal Title

Journal of Alloys and Compounds

Volume

634

Publication Date

1-1-2015

Document Type

Article

Language

English

First Page

168

Last Page

178

WOS Identifier

WOS:000350915200027

ISSN

0925-8388

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