Phase aluminium-copper

The aluminium-copper phase diagram is shown below. 

Fig. 20.43 Aluminium-rich end of the aluminium-copper phase diagram...

Z.R. Ismagilov, D.A. Arendarskii and O.A. Kirichenko, Investigation of catalysts and reaction of catalytic combustion. IV Genesis of the phase composition of supported oxide aluminium-copper-chromium catalysts, Kinet, Ratal., 30 (4) (1989) 918-926. 

Aluminium-Copper. Al-Cu forms a simple eutectic system in the range Irom 0 to 53wt% Cu, as shown in Fig. 3.1-11. The a-Al solid solution and the intermetallic compound AI2Q1 (0 phase) are in equilibrium. At intermediate temperatures, metastable transition phases may form and precipitate from the supersaturated solid solution. These metastable phases may be characterised according to their crystal structure, the nature of the phase boundary they form, and their size ... 

Aluminium-Copper-Lithium. In addition to binary phases between all three elements, three ternary phases, AlyCu Li, A CuLi, and AIsLIbCu, occur in equilibrium with the Al-rich solid solution in the aluminium-rich comer of this system. 

Aluminium-copper-chromium oxide catalysts are widely used in highly exothermal catalytic combustion and VOC removal,though, the interaction of the active component with the support through catalytic process yields phase conversions and deactivation of the catalyst [1-5]. To increase the catalyst thermostability, which is primarily determined by that of the support, the latter is modified by various additives, decelerating phase conversion in the support [6-7]. 

Supported copper-chromium oxide catalysts. The non-modified support after its thermal treatment at 773 K, if coated with a 7% (Cu+Cr) mixture, seems to contain a series of spinel-type phases on the base of the support and copper chromite structures as well. Then diffractogramms of the sample are characterized by distorted lines of the support only. After thermal treatment at 1273 K, there coexist a-Al203 with the increased cell parameter and aluminium-copper-chromium spinel with a = 8.098 A, which is typical for Cu(Ali 8Cro.2)04 composition. No lines of copper (+1), i.e. Cu2Cr204 and CU2AI2O4, are observed. 

Figure 6.46(a) shows part of the phase diagram of the Al-Cu system. One prerequisite for precipitation hardening is the existence of a two-phase region where the matrix phase (in the example, aluminium with copper in solid solution) is in equilibrium with the precipitation phase (a copper-rich phase in the example), a so-called miscibility gap (see section C.3). 

I ig. 5.8 (a) A triple lamellar ternary eutectic in the system cadmium dy-tin Ui)-lead (y). The lamellar arrangement is ay0yy.y (Kerret al.20), (b)The complex ternary eutectic in the aluminium-copper-magnesiiim system. The lamellar phases are aluminium and CuAh and thefibrous phase is Mg-rich (Cooksey ctndHellawelTtt-). 

When the phase diagram for an alloy has the shape shown in Fig. 10.3 (a solid solubility that decreases markedly as the temperature falls), then the potential for age (or precipitation) hardening exists. The classic example is the Duralumins, or 2000 series aluminium alloys, which contain about 4% copper. 

The alloy aluminium-4 wt% copper forms the basis of the 2000 series (Duralumin, or Dural for short). It melts at about 650°C. At 500°C, solid A1 dissolves as much as 4 wt% of Cu completely. At 20°C its equilibrium solubility is only 0.1 wt% Cu. If the material is slowly cooled from 500°C to 20°C, 4 wt% - 0.1 wt% = 3.9 wt% copper separates out from the aluminium as large lumps of a new phase not pure copper, but of the compound CuAlj. If, instead, the material is quenched (cooled very rapidly, often by dropping it into cold water) from 500°C to 20°C, there is not time for the dissolved copper atoms to move together, by diffusion, to form CuAlj, and the alloy remains a solid solution. 

Single-phase solid solution of copper in aluminium... 

Today the sulphonation route is somewhat uneconomic and largely replaced by newer routes. Processes involving chlorination, such as the Raschig process, are used on a large scale commercially. A vapour phase reaction between benzene and hydrocholoric acid is carried out in the presence of catalysts such as an aluminium hydroxide-copper salt complex. Monochlorobenzene is formed and this is hydrolysed to phenol with water in the presence of catalysts at about 450°C, at the same time regenerating the hydrochloric acid. The phenol formed is extracted with benzene, separated from the latter by fractional distillation and purified by vacuum distillation. In recent years developments in this process have reduced the amount of by-product dichlorobenzene formed and also considerably increased the output rates. 

Fig. 1.58 Pit on aluminium showing how the rate of pitting may be facilitated by an intermetallic phase (Al3pe) or by a deposit of copper (after Wranglen )...

Yoshimura et al. [193] carried out microdeterminations of phosphate by gel-phase colorimetry with molybdenum blue. In this method phosphate reacted with molybdate in acidic conditions to produce 12-phosphomolybdate. The blue species of phosphomolybdate were reduced by ascorbic acid in the presence of antimonyl ions and adsorbed on to Sephadex G-25 gel beads. Attenuation at 836 and 416 nm (adsorption maximum and minimum wavelengths) was measured, and the difference was used to determine trace levels of phosphate. The effect of nitrate, sulfate, silicic acid, arsenate, aluminium, titanium, iron, manganese, copper, and humic acid on the determination were examined. 

G. Ghosh, Aluminium-chromium—copper, in Ternary Alloys A Comprehensive Compendium of Evaluated Constitutional Data and Phase Diagrams, G. Petzow and G. Effenberg, Ed., VCH Publishers, New York, 1992, pp. 311-319. 

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