Tantalum boride has been sintered under high temperature and high pressure (HTHP) conditions by using a DS6×8 MN cubic press device, and the Vickers hardness of TaB has been measured by using a diamond indentation method. Under the applied load of 29.4 N, our test gave the Vickers hardness of TaB are 7.7±0.4 and 10.5±0.7 GPa, at 4 GPa and the temperatures of 900 and 1100 ℃, respectively. Our result shows that the density becomes better with the increasing temperature under the same pressure. By using the Archimedes method, we calculated the relative density of 13.5 g/cm3 for TaB.
