Behavior of Some Refractory Hafnium and Tantalum Compounds in Plasma Flows

— By reacting tantalum or hafnium carbide with iridium in the presence of a small amount of silicon, we have prepared refractory hafnium- and tantalum-containing materials consisting of a mixture of phases: the intermetallic compound MIr 3 , recrystallized tantalum or hafnium carbide, and iridium silicide. We have studied the behavior of the materials during an exposure to a high-speed plasma flow at a sample surface temperature of 2000°C and demonstrated that, owing to their special microstructure, the absence of pores, and the low oxidation rate of the iridium-containing components, they exhibit a good ablation resistance and that the hafnium system withstands a longer exposure.