Rhenium and its alloys

This paper reports on the scarcity and high cost of pure rhenium (Re) which precludes its extensive use for large structural components. Typical applications include wear resistant electrical contacts and mass-spectrometer cathodes. The metal is also being considered for components of the reactor core of space nuclear power systems. Rhenium and rhenium-containing alloys are primarily produced by powder metallurgy (P/M) techniques. Melting of these materials in vacuum or in a high-purity inert-gas atmosphere often is prohibitively expensive and time-consuming, as is their production via chemical vapor deposition. P. M rhenium is characterized by a fine-grain polyhedral crystal structure, whereas arc-cast rhenium has a coarser structure and a grain size that varies with location in the ingot. As-sintered P. M rhenium has a density of 90 to 92% of theoretical.