Synthesis of Hard Materials by Field Activation: The Synthesis of Solid Solutions and Composites in the TiB2–WB2–CrB2 System |
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| Authors: | Hisashi Kaga Ellen M. Heian Zuhair A. Munir Clemens Schmalzried Rainer Telle |
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| Affiliation: | Department of Chemical Engineering and Materials Science, University of California, Davis, California 95616;Institut für Gesteinhüttenkunde, Rheinisch-Westfalische Technische Hochschule, Aachen, Germany |
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| Abstract: | The synthesis of solid solutions of (Ti,W,Cr)B2 from elemental reactants using the field-activated, pressure-assisted synthesis method and employing the SPS apparatus was investigated. The nature of the products depended on temperature; they were nearly pure solid solutions at 1900°C with minor amounts of β-WB. The product density and microhardness depended on the temperature of synthesis for the same value of applied pressure (64 MPa). Samples with the highest density (94%) corresponded to a hardness of 22.7 GPa. When annealed at 1500°C, the solid solutions decomposed, precipitating a (W,Ti,Cr)B2 phase in a spinodal form. In addition, β-WB precipitates in the form of thin (0.4–5.3 nm) layers were observed. They existed in a 60°/120° orientation to the (Ti,W,Cr)B2 matrix, in agreement with previous observations. Highly faceted, small (nanosized) pores associated with the β-WB precipitates were also observed. |
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| Keywords: | synthesis composites titanium boride |
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