Tantalum Boride powders were synthesized by the solid state reaction between tantalum and amorphous boron. Five Boride phases (Ta
2B, Ta
3B
2, TaB, Ta
3B
4 and TaB
2) were formed by heat treatment of the mixed powders at 1000°-1800°C for 0-120min. Formation behavior of these borides was dependent on the heat-treatment temperature, in which structurally stable phases formed in order from low to high temperatures. Single phases of TaB
2, TaB and Ta
3B
4 were obtained by the heat-treatment of the mixed powders with corresponding stoichiometric compositions at 800°, 900° and 1800°C, respectively. Sintered compacts of TaB and TaB
2+x were prepared by a high-pressure sintering of synthesized TaB and TaB
2+x powders at 4GPa and 1600°C for 15min. The bulk density of TaB was 13.51g/cm
3 (relative density: 95.1%) and the Vickers microhardness was 2550kg/mm
2. The homogeneous range of the solid solution TaB
2+x was 0<x<0.55, the density and the microhardness of which increased with increasing amount of boron in solid solutions.
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