Details
Material hierarchy: Metal - Nonferrous metal
Beryllium is lighter than aluminum, with a density of 1.848 g/cm3, yet it is stiffer than steel, with a modulus of elasticity of 42 × 106 psi. Beryllium alloys, which have yield strengths of 30,000 to 50,000 psi, have high specific strengths and maintain both strength and stiffness to high temperatures. Instrument grade beryllium is used in inertial guidance systems where the elastic deformation must be minimal; structural grades are used in aerospace applications; and nuclear applications take advantage of the transparency of beryllium to electromagnetic radiation.
Beryllium is expensive, brittle, reactive, and toxic. Its production is quite complicated, requiring that a beryllium sulfate be obtained from the ore, converted to beryllium hydroxide, dissolved and precipitated as a fluoride, and finally reacted with magnesium to produce the metal. The limited availability of ores and the expensive processing make the cost of beryllium metal high. Beryllium has the HCP crystal structure and limited ductility at room temperature, but when exposed to the atmosphere at elevated temperatures, it rapidly oxidizes to form BeO. These problems require the use of sophisticated manufacturing techniques, such as vacuum casting, vacuum forging, and powder metallurgy, further adding to the expense. Finally, BeO is a carcinogenic material for some people, and special care and equipment are used when beryllium is processed.