86 



UNITED STATES MINERAL RESOURCES 



it develops a coherent oxide coating when exposed 

 to air, which protects it from further oxidation and 

 increases its apparent hardness. Unfortunately, 

 oxygen-free beryllium metal is very difficult to pre- 

 pare. Most metal in commerce contains nearly 2 

 percent oxygen, which contributes to its brittle- 

 ness. This brittleness requires production of articles 

 by powder metallurgy and machining — a costly pro- 

 cedure — and limits reshaping by rolling or drawing. 

 The high thermal conductivity, high melting point, 

 high specific heat, low density, and rigidity of the 

 metal make it useful in heat sinks and in specialized 

 structural elements for aircraft and spacecraft. Its 

 low neutron absorption and its emission of neutrons 

 under appropriate gamma or alpha bombardment 

 lead to uses in nuclear energy. In the early 1970's, 

 nearly 20 percent of the beryllium extracted was 

 used as the metal. 



PROPERTIES AND USES OF BERYLLIUM ALLOYS 



More than half the beryllium reduced from its 

 ore is used in alloys, principally in beryllium-copper 

 alloys containing about 2 percent beryllium and 

 about 0.2 percent nickel or cobalt. These alloys have 

 the greatest strength and wear resistance of any 

 nonmagnetic material, with a tensile strength about 

 twice that of hard-drawn iron and two-thirds that 

 of mild steel. They also are excellent conductors of 

 electricity and heat and are very resistant to cor- 

 rosion. Below a temperature of about 300°F, they 

 are much more resistant to fatigue than steel. They 

 are much used in springs, electrical connectors, and 

 many other specialized items. The use of the alloys 

 in computers and other electrical equipment has 

 resulted in greatly increased consumption during the 

 last 20 years. 



Beryllium has been used in small amounts with 

 nickel to make hardenable alloys with very high 

 tensile strength that are usable at higher tempera- 

 tures than copper alloys. 



In light alloys with aluminum and magnesium, 

 beryllium can improve the properties or facilitate 

 the production of the metal. Addition of 0.02 per- 

 cent of beryllium to aluminum-magnesium alloys 

 reduces reaction with green sand molds and im- 

 proves oxidation resistance. It eliminates the need 

 for elaborate precautions against burning of mag- 

 nesium, inasmuch as the molten metal containing 

 beryllium can be poured safely at a temperature of 

 1,400°F. "Lockalloy," containing 62 percent beryl- 

 lium and 38 percent aluminum, has some of the desir- 

 able properties of beryllium, is reasonably workable, 

 and can be used at temperatures as high as 800°F. 

 Various composite materials containing beryllium in 



nonbrittle matrices are strong and light. 



PROPERTIES AND USES OF THE OXIDE 



Beryllium oxide is the third major form in which 

 beryllium is used. This oxide, with a high melting 

 point, a high thermal conductivity, and very low 

 electrical conductivity, can be used as an electrical 

 insulator in applications where heat must be trans- 

 ferred or dissipated, as in power transistors. The 

 high thermal conductivity results in high thermal 

 shock resistance, which is important in special 

 ceramics. These, and the nuclear properties, lead to 

 the use of beryllium oxide in reactor fuel elements. 



BERYL AS AN INDUSTRIAL MINERAL 



In addition to the uses of beryllium that require 

 extraction of the metal from its ore, there are many 

 uses that are met by incorporating undecomposed 

 beryl into an industrial product. These uses account 

 for about one-tenth of the beryl ore used during the 

 last 20 years. Some of these uses are chemical — 

 the addition of beryllium to a ceramic or glass mix ; 

 others rely upon one or more physical properties of 

 the mineral beryl itself such as its structure, its 

 thermal conductivity, or its ability to adhere to 

 plastics. 



END USES OF BERYLLIUM 



The amount of beryllium used in various ways 

 in the United States is summarized in table 15. 



Table 15. — End uses of beryllium in the United States, 1968 



[Data from Heindl, 1970, p. 498] 



Use 



Nuclear applications 



Guided missiles and space vehicles 



Instruments 



Switch gear 



Welding equipment 



Electronic computers 



Radio and television equipment 



Other 



Total 



35 

 35 

 45 

 90 

 40 

 40 

 25 

 38 



10 

 10 

 13 

 26 

 11 

 11 

 6 

 13 



100 



SECONDARY RECOVERY 



Much recoverable beryllium scrap is produced in 

 making articles out of beryllium metal. This is an 

 inevitable result of the necessity of making blank 

 or roughly formed pieces of metal by powder metal- 

 lurgy, then machining the final product from them. 

 Not much metal, however, can be salvaged from 

 the final articles. Components of missiles and rockets 

 are commonly destroyed in use, whereas those of 

 manned capsules and orbiting observatories may be 



