Carbide phases formed in WC-M (M = Fe/Ni/Cr) systems

The effect of composition in the formation of carbides in the WC-M (M = Fe/Ni/Cr) system has been studied. Three conventional compositions have been prepared with 10 wt.% of metallic binder. Fe as a metallic binder was first studied and its partial substitution by Ni and Cr was also investigated. A WC powder coated with a similar binder (Fe/Ni/Cr) amount was also investigated. The XRD results, after thermal treatment at 1400 degrees C, reveal that the substitution of half percent of the iron content by Ni stabilized the austenite Fe(gamma) formation. The introduction of Cr in the binder composition induces the formation of Cr2C carbide. With the decrease of Cr amount in the binder composition of the coated powder, Cr2C carbide was not formed, but instead other carbide, M6C, was detected. In order to eliminate this carbide a small excess of carbon (3.6 wt.%) was added to the coated powder. The results are discussed in terms of the phases formed, the binder composition and the final carbon content. (C) 2007 Elsevier Ltd and Techna Group S.r.l. All rights reserved.