CARBOTHERMIC REDUCTION OF A COLUMBITE CONCENTRATE TO PRODUCE CEMENTEDCARBIDES AND METAL-MATRIX COMPOSITES

The study of the carbothermic reduction of a columbite concentrate was carried out to form cemented carbides based on particles of (Nb, Ta)C solid solution bonded together by ferromanganese. The effect of vario us parameters on the kinetics of reaction were examined. Complete wett ing of the carbide phase by the metal was achieved. Metal-matrix compo sites (MMC) based on (Nb, Ta)C and cast iron were also obtained and th e morphology is described. Addition of Ni to the MMC had a profound ef fect on the microstructure and carbide distribution in the matrix.