Alloys containing beryllium

The addition of beryllium and silicon to nickel-palladium alloys gives very good high-temperature brazes, especially for alloys containing aluminium and titanium. 

Beryllium, beryllium-containing alloys, and beryllium oxide ceramic in solid or massive form present no hazard whatsoever (31). Solid shapes maybe safely handled with bare hands (32) however, care must be taken in the fabrication and processing of beryllium products to avoid inhalation of airborne beryllium particulate matter such as dusts, mists, or fumes in excess of the prescribed workplace exposure limits. Inhalation of fine airborne beryllium may cause chronic beryllium disease, a serious lung disease in certain sensitive individuals. However, the vast majority of people, perhaps as many as 99%, do not react to beryllium exposure at any level (33). The biomedical and environmental aspects of beryllium have been summarized (34). 

Beryllium (Be) is in group 2A and is the first metal in the periodic table to be notably toxic. When fluorescent lamps and neon lights were first introduced, they contained beryllium phosphor a number of cases of beryllium poisoning resulted from the manufacture of these light sources and the handling of broken lamps. Modem uses of beryllium in ceramics, electronics, and alloys require special handling procedures to avoid industrial exposure. 

Other popular alloys of beryllium are those with copper metal. Copper-beryllium alloys contain about 2 percent beryllium. They conduct heat and electricity almost as well as pure copper but are stronger, harder, and more resistant to fatigue (wearing out) and corrosion (rusting). These alloys are used in circuit boards, radar, computers, home appliances, aerospace applications, automatic systems in factories, automobiles, aircraft landing systems, oil and gas drilling equipment, and heavy machinery. 

GENETRON 113 (Allied Signal) (76-13-1) Reacts violently with chemically active metals, barium, calcium, lithium, potassium, sodium, and powdered aluminum, beryllium, magnesium, potassium-sodium alloy, titanium, zinc. Contact with alloys containing more than 2% magnesium or with hot surfaces can cause decomposition with the release of... 

Be unfortunately, this is still contained in some dental alloys because the mechanical qualities are improved by its presence. Indeed, beryllium is highly allergenic and toxic, and several cases of lung berylliosis have been reported in dental technicians working with alloys containing Be (Lob and Hugonnaud 1977 Choudat 1982 Choudat etal. 

Some copper-rich alloys containing no tin are also called bronzes. Aluminum bronzes, for example, with up to 10% aluminum, are strong, resistant to corrosion and wear, and can be worked cold or hot silicon bronzes, with 1-5% silicon, have high corrosion-resistance beryllium bronzes, with about 2% beryllium, are very hard and strong. 

Ammonium hydroxide solutions also attack copper-zinc alloys. Alloys containing more than 15 % zinc are susceptible to see when stressed and exposed to ammonium hydroxide, although it also is experienced by the copper-beryllium alloys which are zinc-free. The stress may be due to applied tensile service loads or to unrelieved residual tensile stresses. 

In dilute uranyl sulfate solutions the addition of sulfate salts also reduces the corrosion of stainless steel, but at temperatures of 250°C and higher the solutions are chemically unstable and complex hydrolytic precipitates form. At lower uranyl sulfate concentrations (0.04 to 0.17 m) the solutions demonstrating the greatest stability are those containing beryllium sulfate, and of the three sulfates most investigated, the least stable of the solutions were those with lithium sulfate. Sulfuric acid can be included in such solutions to prevent precipitation, but in so doing some of the effectiveness of the sulfate salt is lost. Howe cr, addition of both lithium. sulfate and sulfuric acid to dilute uranyl sulfate solutions has been found to result in improved corrosion resistance of zirconium alloys on in-pile exposure [35]. 

There was also the possibility that alloying magnesium with other metals might improve the corrosion properties, and the results were tested at Harwell. One alloy, containing 0.05% beryllium, 0.1% calcium and 1% aluminium, showed remarkable resistance to corrosion. No measurable attack occurred below 600°C in wet air, which is the most generally corrosive environment. 

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