Copper-Aluminum Alloys

Aluminum bronzes have progressed from simple copper-aluminum alloys to more complex alloys with the addition of iron, nickel, silicon, manganese, tin, and other elements. 

The aluminum content is primarily responsible for the microstructure of these bronzes. A single-phase alpha structure is present in alloys containing approximately 8% aluminum. As the aluminum content is increased, other constituents appear in the microstructure. They may be beta, alpha-gamma eutectoid, or a combination, depending on the aluminum content, the cooling rate from solidification, and the heat treatment. An iron-rich intermetallic compoimd is generally formed when iron is added, whereas the addition of nickel above 2% tends to introduce an additional kappa phase. 

Aluminum bronzes are resistant to nonoxidizing mineral acids such as phosphoric and sulfuric. The presence of an oxidizing agent controls their resistance. 

These alloys are also resistant to many organic acids such as acetic, citric, formic, and lactic. The possibility of copper pickup by the finished product may limit their use. Such a pickup may discolor the product even though it is very, very low in concentration. 

Dealloying is rarely seen in all alpha, single-phase alloys such as UNS C60800, C61300, or C61400. When dealloying does occur, it is in conditions of low pH and high temperature. 

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The electrorefining of many metals can be carried out using molten salt electrolytes, but these processes are usually expensive and have found Httie commercial use in spite of possible technical advantages. The only appHcation on an industrial scale is the electrorefining of aluminum by the three-layer process. The density of the molten salt electrolyte is adjusted so that a pure molten aluminum cathode floats on the electrolyte, which in turn floats on the impure anode consisting of a molten copper—aluminum alloy. The process is used to manufacture high purity aluminum. 

Raney copper is prepared by intensive leaching of a commercial copper-aluminum alloy (50-50 wt%) washed with water until neutral. Bimetallic catalysts are obtained using an oxido-reduction method summarized as n Cu-s + 2 Mn+ -> n Cu2+ + 2 Ms... 

The solubilities of gases in solid metals are much lower than liquid metals. Figure 10.18 shows the solubility of hydrogen in copper and copper-aluminum alloys. Because of the lower solubility in the solid, gas bubbles are released at the liquid-solid interface as the metal freezes. With long dendrites the gas bubbles are trapped and the result is gas porosity. 

Table 4,26 Some common wrought copper-aluminum alloys chemical composition...

Bromoanilines are reduced to anilines by hydrogenation over Raney nickel (equation 55), and p-bro-moacetophenone is converted to 1-phenylethanol on heating at 50 C with Raney alloys in 5% sodium hydroxide. The best yields are obtained using copper-aluminum alloy (89-91%). ... 

Raney copper is another Raney type catalyst that is prepared from a copper-aluminum alloy. This catalyst has been used infrequently but does show some reaction selectivity not possible with other catalysts. Of particular interest is its use for the selective hydrogenation of substituted dinitrobenzenes (Eqn. 11.6).2 This catalyst, as well as Raney cobalt, generally promotes fewer side reactions than does Raney nickel. 25... 

Raney copper is prepared from the commercially available copper aluminum alloy. It does not have much to offer the synthetic chemist as only a few reactions are reported to be affected by this catalyst. Raney copper, as well as Raney cobalt, generally produces fewer side reactions than Raney nickel even though they usually require higher reaction temperatures for the same reaction. Raney copper is, however, quite usefiil for the selective hydrogenation of substituted dinitro benzenes (Eqn. 8.6) with its activity apparently increasing with continued reuse. Raney copper can also be used for the catalytic hydrolysis of hindered nitriles to the amides (Eqn. 12.13). "2... 

Tierney BJ, Pitner WR, Mitchell JA et al (1998) Electrodeposition of copper and copper-aluminum alloys from a room-temperature chloroaluminate molten salt. J Electrochem Soc 145 3110-3116... 

K. Sieradzki, J.S. Kim, A.T. Cole, R.C. Newman, The relationship between dealloying and transgranular stress-corrosion cracking of copper-zinc and copper-aluminum alloys, J. Electrochem. Soc. 134 (1987) 1635-1639. 

FIGURE 13 Examples of kinetic processes classified by types of phases involved, (a) Gas-gas reaction equilibrium between hydrogen gas, iodine gas, and hydrogen iodide gas. (f>) Gas-Uquid evaporation of liquid water from a glass, (c) Liquid-Liquid gradual separation of an oil-water mixture, (d) Gas-solid chemical vapor deposition of a thin Si film, (e) Liquid-solid corrosion of Cu metal in seawater, (f) Solid-solid precipitation of CuAlj particles from a copper-aluminum alloy during a heat treatment process. 

An example of this type of reduction is that of benzaldehyde to 1-d-benzyl alcohol by a copper-aluminum alloy in the presence of deuterium oxide and sodium carbonate.Huffman et al observed that the stereoselectivity of camphor reduction is the same either sonochemically in THF or silently in liquid ammonia with the usual three alkali metals (Eq. 13),106... 

Similarly, a cyanide was reduced to the primary amine with an adjacent CD2 group, when sonicated in the presence of a copper-aluminum alloy and sodium deuteroxide in deuterium oxide. s... 

Metals such as brass, bronze. Monel metal (copper-nickel alloy), copper-aluminum alloys (aluminum bronze), copper-beryllium alloys (beryllium bronze), and titanium. 

Other alloy systems are also susceptible to this form of corrosion. Refer to Table 1.6. Selective leaching of aluminum takes place in aluminum bronze exposed to hydrofluoric acid or acid-containing chlorides. Copper-aluminum alloys containing more than 80% aluminum are particularly susceptible. 

Bronzes Alloys in which the major alloying element is neither zinc nor nickel four major families of bronze exist copper-tin-phosphorus (phosphor bronze), copper-tin-lead-phosphorus (leaded phosphor bronze), copper-tin-nickel alloys (nickel-tin-bronzes), and copper-aluminum alloys (aluminum bronzes)... 

Wrought Copper-Aluminum Alloys Maximum Composition (%)... 

D. H, Buckley Chemical shifts, while observed were not of sufficient magnitude to draw any strong conclusions therefrom. We have observed significant chemical shifts with other systems, for example, the formation of aluminum oxide from the interaction of oxygen with aluminum on a copper-aluminum alloys where the shift is of sufficient magnitude to be really meaningful. 

C6xxxx Copper-aluminum alloys, copper-silicon alloys (silicon bronzes), and other copper-zinc alloys... 

Copper-tin alloys (76 Cu-22 Zn-2 Al), also known as tin bronze, show increased corrosion rates with increased temperature compared to Cu-Al alloys. The corrosion resistance of copper-aluminum alloys increases with increasing aluminum content. Alpha alloys (or-aluminum bronze) consists of single (alpha) phase up to 7% aluminum and two phase (or -t- or a -f y) above 7%. Aluminum bronzes exhibit an outstanding resistance to corrosion in seawater and offer a good resistance to impingement corrosion. 

Part 4. Copper-aluminum alloys (aluminum bronzes) ... 

Uses Low foaming alkaline cleaner for nonferrous metals for spray cleaning of copper, aluminum alloy, brass, magnesium alloy, etc. 

A more modern approach for the direct introduction of a carbon side-chain into the pteridine nucleus has been developed by homolytic nucleophilic substitution reactions , especially using acyl radicals -i as well as alkyl radicals as reactive species. These reactions, however, take place regioselectively with 6,7-unsubstituted pteridine derivatives at the most electron-deficient 7-position leading to the unnatural isomers. Direction of the incoming nucleophile towards the C-6 atom can only be achieved in the presence of a 7-substituent " . A reasonable "protecting" group for C-7 has been the alkylmercapto and thione function, since it was found that the difficulties encountered with the Raney-nickel desulfurization reaction " in the pteridine series could be overcome using Raney-cobalt and copper-aluminum alloy, respectively . 

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