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Post Info TOPIC: Tungsten tetraboride


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Tungsten tetraboride
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Title: Tungsten tetraboride, an inexpensive superhard material
Authors: Reza Mohammadi, Andrew T. Lech, Miao Xie, Beth E. Weaver, Michael T. Yeung, Sarah H. Tolbert, and Richard B. Kaner

Tungsten tetraboride (WB4) is an interesting candidate as a less expensive member of the growing group of superhard transition metal borides. WB4 was successfully synthesized by arc melting from the elements. Characterisation using powder X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX) indicates that the as-synthesised material is phase pure. The zero-pressure bulk modulus, as measured by high-pressure X-ray diffraction for WB4, 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 WB4 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.

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