Densification and FIB, SEM, TEM Microstructures of WC Composites with Fe or Co Matrices

摘要

The present work refers to results obtained in the synthesis of tungsten carbide embedded in a metal matrix such as Co or Fe, through different routes and from various precursors. The two principal methods were, an aqueous, and the other one, a sol-gel using alkoxides. Heat treatments were carried out in an alumina oven with SiC heating elements, and covered different heating schedules under several atmospheres (gas flows and vacuum). Resulting phases after the different heat treatments were studied by X ray diffraction (showing the formation of desired phases, WC and the metal matrices Fe or Co) and final microstructure waqs analyzed through techniques suchs as SEM (Scanning electron microscopy), FIB (Focused ion beam) and TEM (Transmission electron microscopy). It was observed that sol-gel internally precipitated WC grains (within a matrix, rich in Fe, and having excess C) had average dimensions of 2 microns. Finally, microhardness (Vickers) values in the range between 937 and 1242 HV were measured for the various kinds of composites.