Effect of Mechanical Activation of Iridium on Its Reaction with Refractory Carbides

— We have studied solid-state reactions of unmilled and ball-milled iridium powders with SiC and WC powders in the temperature range 800–1400°C. Interaction of iridium with SiC leads to the formation of various iridium silicides, whose composition and concentration depend on the reaction mixture treatment temperature and iridium particle size. Interaction of iridium with WC leads to the formation of a W x Ir 1 –x intermetallic phase with a broad homogeneity range. Mechanical treatment of iridium powder has been shown to markedly speed up solid-state reactions between the iridium and refractory carbides, primarily owing to the associated increase in the specific surface area of the iridium and the accumulation of structural defects.