title: Crystal structure and carbon vacancy hardening of (W0.5Al0.5)C1-x prepared by a solid-state reaction.
abstract: Novel solid solutions of aluminum in tungsten carbide (WC) with or without carbon vacancies, which can be expressed by the chemical formula (W(0.5)Al(0.5))C(1-x) (x=0.0-0.5), have been synthesized by the solid-state reaction of W(0.5)Al(0.5) alloy and the proper amount of carbon at around 1673 K in vacuum. The reaction time decreases from 73 to 50 h on increasing the carbon vacancy concentration from 0 to 50 %. The formation of the intended products is certified, by X-ray diffraction, environmental scanning electron microscopy-energy-dispersive X-ray analysis, and inductively coupled plasma-atomic emission spectroscopy, even though the carbon vacancy concentration reaches the astonishing value of 50 %. The as-prepared (W(0.5)Al(0.5))C(1-x) samples have been identified as the hexagonal WC-type structure belonging to the space group P6m2 (Z=1). Moreover, the crystallographic results reveal that the substituting aluminum atoms in the WC are located in the 1a site (the W atom position of the WC structure) and the cell parameters decrease slightly with increasing vacancy concentration. The hardness of the (W(0.5)Al(0.5))C(1-x) system increases up to a maximum 2659 kg mm(-2) at a carbon vacancy concentration of about 35 %, and the density of (W(0.5)Al(0.5))C(1-x) is far lower than that of WC.
authors.affiliation: Laboratory of Materials and Devices, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China.
authors.forename: Junmin
authors.initials: J
authors.lastname: Yan
authors.forename: Xianfeng
authors.initials: X
authors.lastname: Ma
authors.forename: Wei
authors.initials: W
authors.lastname: Zhao
authors.forename: Huaguo
authors.initials: H
authors.lastname: Tang
authors.forename: Changjun
authors.initials: C
authors.lastname: Zhu
authors.forename: Shuguang
authors.initials: S
authors.lastname: Cai