Novel solid solutions of Al in tungsten carbide, with or without C vacancies, W0.5Al0.5C1-x (x = 0.0 to 0.5), were synthesized via the solid-state reaction of W0.5Al0.5 alloy and the correct amount of C at around 1673K in vacuum. The reaction time decreased from 73 to 50h upon increasing the C vacancy concentration from 0 to 50%. Formation of the intended products was confirmed by X-ray diffraction, environmental scanning electron microscopy-energy-dispersive X-ray analysis and inductively coupled plasma-atomic emission spectroscopy; even though the C vacancy concentration attained 50%. The as-prepared W0.5Al0.5C1-x samples were identified as having an hexagonal WC-type structure belonging to the space group P6m2 (Z=1). The crystallographic results revealed that the substituted Al atoms were located in the 1a site (W-atom position of the WC structure) and the cell parameters decreased slightly with increasing vacancy concentration. The hardness of the W0.5Al0.5C1-x system increased up to a maximum of 2659kg/mm2 at a C vacancy concentration of about 35%, and the density was far lower than that of WC.

Crystal Structure and Carbon Vacancy Hardening of (W0.5Al0.5)C1-x Prepared by Solid-State Reaction. J.Yan, X.Ma, W.Zhao, H.Tang, C.Zhu, S.Cai: ChemPhysChem, 2005, 6[10], 2099-103