Hexagonal OsB2: Sintering, microstructure and mechanical properties

Zhilin Xie; Mykola Lugovy; Nina Orlovskaya; Thomas Graule; Jakob Kuebler; Martin Mueller; Huili Gao; Miladin Radovic; David A. Cullen

doi:10.1016/j.jallcom.2015.01.291

Hexagonal OsB₂: Sintering, microstructure and mechanical properties

Zhilin Xie, Mykola Lugovy, Nina Orlovskaya, Thomas Graule, Jakob Kuebler, Martin Mueller, Huili Gao, Miladin Radovic, David A. Cullen

Materials MicroAnalysis

Research output: Contribution to journal › Article › peer-review

20 Scopus citations

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 (∼80 wt.%) and orthorhombic (∼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.

Original language	English
Pages (from-to)	168-178
Number of pages	11
Journal	Journal of Alloys and Compounds
Volume	634
DOIs	https://doi.org/10.1016/j.jallcom.2015.01.291
State	Published - Jun 5 2015

Bibliographical note

Publisher Copyright:
© 2015 Elsevier B.V. All rights reserved.

Funding

This work was supported by NSF project DMR – 0748364 . The bulk of electron microscopy work was performed as part of a user project supported by ORNL’s Center for Nanophase Materials Sciences (CNMS) , which is a DOE Office of Science User Facility. M.M.’s and N.O.’s work at EPFL, which included nanoindentation experiments, was supported by the European Research Council under the European Union’s Seventh Framework Programme (FP/2007–2013)/ERC Advanced Grant Agreement No. 291085 and N.O.’s work at Empa was supported by the Swiss National Science Foundation, International Short Visit , IZK0Z2_154379 . The authors would also like to thank Prof. A. Mortensen, EPFL for his valuable suggestions and revisions of the manuscript.

Funders	Funder number
CNMS
ORNL’s Center for Nanophase Materials Sciences
National Science Foundation	DMR – 0748364
Office of Science
Seventh Framework Programme	FP/2007–2013
Engineering Research Centers	291085
European Research Council
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung	IZK0Z2_154379

Keywords

Ceramic
Mechanical properties
Nanoindentation
Osmium diboride

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10.1016/j.jallcom.2015.01.291

Cite this

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title = "Hexagonal OsB2: Sintering, microstructure and mechanical properties",

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 (∼80 wt.%) and orthorhombic (∼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.",

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AU - Xie, Zhilin

AU - Lugovy, Mykola

AU - Orlovskaya, Nina

AU - Graule, Thomas

AU - Kuebler, Jakob

AU - Mueller, Martin

AU - Gao, Huili

AU - Radovic, Miladin

AU - Cullen, David A.

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N2 - 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 (∼80 wt.%) and orthorhombic (∼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.

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