Abstract
Tantalum Boride powders were synthesized by the solid state reaction between tantalum and amorphous boron. Five Boride phases (Ta2B, Ta3B2, TaB, Ta3B4 and TaB2) 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 TaB2, TaB and Ta3B4 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 TaB2+x were prepared by a high-pressure sintering of synthesized TaB and TaB2+x powders at 4GPa and 1600°C for 15min. The bulk density of TaB was 13.51g/cm3 (relative density: 95.1%) and the Vickers microhardness was 2550kg/mm2. The homogeneous range of the solid solution TaB2+x was 0<x<0.55, the density and the microhardness of which increased with increasing amount of boron in solid solutions.
