title: Tungsten tetraboride, an inexpensive superhard material.
abstract: Tungsten tetraboride (WB(4)) is an interesting candidate as a less expensive member of the growing group of superhard transition metal borides. WB(4) was successfully synthesized by arc melting from the elements. Characterization using powder X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX) indicates that the as-synthesized material is phase pure. The zero-pressure bulk modulus, as measured by high-pressure X-ray diffraction for WB(4), is 339 GPa. Mechanical testing using microindentation gives a Vickers hardness of 43.3 ± 2.9 GPa under an applied load of 0.49 N. Various ratios of rhenium were added to WB(4) in an attempt to increase hardness. With the addition of 1 at.% Re, the Vickers hardness increased to approximately 50 GPa at 0.49 N. Powders of tungsten tetraboride with and without 1 at.% Re addition are thermally stable up to approximately 400 °C in air as measured by thermal gravimetric analysis.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA.
authors.forename: Reza
authors.initials: R
authors.lastname: Mohammadi
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Lech
authors.forename: Miao
authors.initials: M
authors.lastname: Xie
authors.forename: Beth E
authors.initials: BE
authors.lastname: Weaver
authors.forename: Michael T
authors.initials: MT
authors.lastname: Yeung
authors.forename: Sarah H
authors.initials: SH
authors.lastname: Tolbert
authors.forename: Richard B
authors.initials: RB
authors.lastname: Kaner