A new solid solution of Al in WC, which can be expressed by the chemical formula (W0.5Al0.5)C, has been synthesized directly by reaction milling (RM) of a W0.5Al0.5 alloy and the proper amount of carbon. The total reaction time is about 50 h. The ESEM photograph shows that the prepared (W0.5Al0.5)C powders are spherical, and the average particle size is about 40 nm. (W0.5Al0.5)C has been identified to crystallize in the hexagonal space group P-6m2 (No. 187) and belongs to the WC structure type. The lattice parameter of (W0.5Al0.5)C is calculated to be a = 2.908(1) angstrom, c = 2.836(1) angstrom. This nanocrystalline powder can be well sintered at the high temperature (1600 degrees C) under the high pressure (4.5 GPa), and the relative density reaches 99.1%. The hardness of the sintered (W0.5Al0.5)C is tested to be 1500 +/- 50 kg mm(-2), while the density is about 9.417 +/- 0.003 g cm(-3), which is far lower than that of WC. (c) 2005 Elsevier Ltd. All rights reserved.