Physics and chemistry of beryllium

The combination of properties of beryllium which results in this very low Z element being a candidate for use in fusion reactors is reviewed. The occurrence, availability, and processing of beryllium from both bertrandite (domestic) and beryl (imported) ores are described. The available beryllium grades are characterized. The purity level of these grades, which are all unalloyed in the usual sense, is presented in detail. The crystallographic factors which establish the physical and mechanical characteristics are reviewed. Powder metallurgy techniques are used almost exclusively to provide beryllium with modest ductility at room temperature (e.g., 3% tensile elongation) and excellent strain capacity at elevated temperature (>40% tensile elongation at 400 °C). The metallurgical behavior of the powder metallurgy product is summarized. The physical properties of this low density metal (1.85 g/cm3) are reviewed with emphasis on the favorable thermal properties. Mechanical properties at room and elevated temperature are presented. The solubility and reactivity of hydrogen with beryllium are both nil while it is an extremely good ‘‘getter’’ for small amounts of oxygen. The combination of beryllium characteristics which has led to the proposed use of beryllium in tokamak reactors as limiter surfaces and in fusion breeders as a neutron multiplying shield are reviewed.