Beryllium alloying element

No fewer than 14 pure metals have densities se4.5 Mg (see Table 10.1). Of these, titanium, aluminium and magnesium are in common use as structural materials. Beryllium is difficult to work and is toxic, but it is used in moderate quantities for heat shields and structural members in rockets. Lithium is used as an alloying element in aluminium to lower its density and save weight on airframes. Yttrium has an excellent set of properties and, although scarce, may eventually find applications in the nuclear-powered aircraft project. But the majority are unsuitable for structural use because they are chemically reactive or have low melting points." ... 

Assay of beryllium metal and beryllium compounds is usually accomplished by titration. The sample is dissolved in sulfuric acid. Solution pH is adjusted to 8.5 using sodium hydroxide. The beryllium hydroxide precipitate is redissolved by addition of excess sodium fluoride. Liberated hydroxide is titrated with sulfuric acid. The beryllium content of the sample is calculated from the titration volume. Standards containing known beryllium concentrations must be analyzed along with the samples, as complexation of beryllium by fluoride is not quantitative. Titration rate and hold times are critical therefore use of an automatic titrator is recommended. Other fluoride-complexing elements such as aluminum, silicon, zirconium, hafnium, uranium, thorium, and rare earth elements must be absent, or must be corrected for if present in small amounts. Copper—beryllium and nickel—beryllium alloys can be analyzed by titration if the beryllium is first separated from copper, nickel, and cobalt by ammonium hydroxide precipitation (15,16). 

Beryllium alloys are usually analyzed by optical emission or atomic absorption spectrophotometry. Low voltage spark emission spectrometry is used for the analysis of most copper—beryllium alloys. Spectral interferences, other inter-element effects, metallurgical effects, and sample inhomogeneity can degrade accuracy and precision and must be considered when constructing a method (17). 

Alloying elements that are particularly effective for improving oxidation resistance at high temperatures are aluminum, beryllium, and magnesium for example, at 256 °C, a 2% Be-Cu alloy oxidizes in Ih at 1/14 the rate of copper [42]. Maximum improvement by aluminum additions occurs at about 8% [43]. 

Fluoroplastics feature high viscosity combined with a low resistance to shear stresses. Large channel diameters and very large gates, with a diameter of as much as 5 mm, are recommended [7]. This requires nozzles with a valve pin to be used. In a plasticised state, the melt has a strong corrosive effect on steel (chemical reaction of fluorine and iron). Steel with a high nickel content is therefore recommended, or else nickel coatings. To improve heat conduction, internal copper beryllium alloy inserts are used in the nozzles, which are pressed into elements made of hardened nickel steel. 

The traditional additions are chromium, manganese (these two elements improve weldability), nickel (improves resistance at high temperatures), titanium (refining the as-cast structure), beryllium, zirconium, lead (free machining alloys), etc. An alloy can contain more than one additive, and their concentrations may exceed 1 % in certain cases. All the alloying elements can also be additives in another series of alloys. 

In summary, a heavy-water-moderated nuclear fission reactor fueled with UO3 or U3O8 can be operated with natural uranium that is produced by means of a standard uranium wet chemistry solvent extraction purification process. Additionally, given the neutronic properties of other elements, it is expected that similar reactors can be operated with uranium carbide, uranium tetrafluoride, and uranium-beryllium alloys. 

Polonium can be mixed or alloyed with beryllium to provide a source of neutrons. The element has been used in devices for eliminating static charges in textile mills, etc. however, beta sources are both more commonly used and less dangerous. It is also used on brushes for removing dust from photographic films. The polonium for these is carefully sealed and controlled, minimizing hazards to the user. 

Many elemental additions to copper for strengthening and other properties also deoxidize the alloy. A side benefit of such additions is elimination of susceptibihty to hydrogen embrittlement. Such deoxidizing additions include beryllium, aluminum, siUcon, chromium, zirconium, and magnesium. 

In the case of alloys having one constituent considerably more reactive to oxygen than the others, conditions of temperature, pressure and atmosphere may be selected in which the reactive element is preferentially oxidised. Price and Thomas used this technique to develop films of the oxides of beryllium, aluminium, etc. on silver-base alloys, and thereby to confer improved tarnish resistance on these alloys. If conditions are so selected that the inward diffusion of oxygen is faster than outward diffusion of the reactive element, the oxide will be formed as small dispersed particles beneath the surface of the alloy. The phenomenon is known as internal oxidation and is of quite common occurrence, usually in association with a continuous surface layer of oxides of the major constituents of the alloy. 

Dilute binary alloys of nickel with elements such as aluminium, beryllium and manganese which form more stable sulphides than does nickel, are more resistant to attack by sulphur than nickel itself. Pfeiffer measured the rate of attack in sulphur vapour (13 Pa) at 620°C. Values around 0- 15gm s were reported for Ni and Ni-0-5Fe, compared with about 0-07-0-1 gm s for dilute alloys with 0-05% Be, 0-5% Al or 1-5% Mn. In such alloys a parabolic rate law is obeyed the rate-determining factor is most probably the diffusion of nickel ions, which is impeded by the formation of very thin surface layers of the more stable sulphides of the solute elements. Iron additions have little effect on the resistance to attack of nickel as both metals have similar affinities for sulphur. Alloying with other elements, of which silver is an example, produced decreased resistance to sulphur attack. In the case of dilute chromium additions Mrowec reported that at low levels (<2%) rates of attack were increased, whereas at a level of 4% a reduction in the parabolic rate constant was observed. The increased rates were attributed to Wagner doping effects, while the reduction was believed to result from the... 

Beryllium is obtained by electrolytic reduction of molten beryllium chloride. The element s low density makes it useful for the construction of missiles and satellites. Beryllium is also used as windows for x-ray tubes because Be atoms have so few electrons, thin sheets of the metal are transparent to x-rays and allow the rays to escape. Beryllium is added in small amounts to copper the small Be atoms pin the Cu atoms together in an interstitial alloy that is more rigid than pure copper but still conducts electricity well. These hard, electrically conducting alloys are formed into nonsparking tools for use in oil refineries and grain elevators, where there is a risk of explosion. Beryllium-copper alloys are also used in the electronics industry to form tiny nonmagnetic parts and contacts that resist deformation and corrosion. 

Although not meeting the foregoing definition of copper precisely, there is a group of copper alloys which contain only a few percent <>r other ingredients and commonly these are also referred lo as coppers, usually with the name of the other element preceding copper in the name—as chromium copper or beryllium copper. These vcry-high-copper alloys are described briefly in Table 2. 

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