Copper-zinc alloys composition

Copper-tin Although a wide range of copper-zinc alloy deposits can be plated, most experience has been gained with two compositions, i.e. the red copper-rich tin-bronze which contains 90-93% copper and 10-7% tin and the white speculum which contains 50-60% copper and 50-40% tin. 

Fig. 9-13. Analytical data obtained by point-to-point exploration with a microprobe, showing the variation of composition of a copper-zinc alloy in a region of diffusion. (After Castaing and Guinier, Anal. Chem., 25, 724.)...

Alloys of copper and zinc can be obtained by combining the molten metals. However, zinc is soluble in copper up to only about 40% (of the total). When the content of a copper/zinc alloy contains less than 40% zinc, cooling the liquid mixture results in the formation of a solid solution in which Zn and Cu atoms are uniformly distributed in an fee lattice. When the mixture contains more than 40% zinc, cooling the liquid mixture results in the formation of a compound having the composition CuZn. The solid alloy consists of two phases, one of which is the compound CuZn and the other is a solid solution that contains Cu with approximately 40% Zn dissolved in it. This type of alloy is known as a two-phase alloy, but many alloys contain more than three phases (multiple-phase alloys). 

Copper and Gold Bronze Pigments. Copper and gold bronze pigments (powdered copper-zinc alloys) are usually produced by dry milling. Depending on the alloy composition, the following natural shades are produced ... 

Brass is a copper-zinc alloy. What is the mass in grams of a brass cylinder having a length of 1.62 in. and a diameter of 0.514 in. if the composition of the brass is 67.0% copper and 33.0% zinc by mass The density of copper is 8.92 g/cm3, and the density of zinc is 7.14 g/cm3. Assume that the density of the brass varies linearly with composition. 

A copper-zinc alloy of composition 75 wt% Zn-25 wt% Cu is slowly heated from room temperature. 

Figure 18.39 Room-temperature electrical resistivity versus composition for copper-zinc alloys.

Alloying metals with impurities results in a reduction in the thermal conductivity, for the same reason that the electrical conductivity is decreased (Section 18.8) namely, the impurity atoms, especially if in solid solution, act as scattering centers, lowering the efficiency of electron motion. A plot of thermal conductivity versus composition for copper-zinc alloys (Figure 19.4) displays this effect. 

Table 16 illustrates the property enhancements and tradeoffs seen when tin is added to a copper—zinc brass base composition. The most commonly used alloys for electrical connectors are the Cu—10 Zn—Sn brasses, such as C411, C422, and C425. These lower level zinc—tin alloys offer good corrosion resistance along with the good formabiHty, conductivity, and strength levels of brass. 

Aluminum drillpipe is generally made of 2014 type aluminum-copper alloy. Composition of this alloy is 0.50 to 1.20% silicon, 1.00% iron maximum, 3.90 to 5.0% copper, 0.40 to 1.20% manganese, 0.25% zinc maximum and 0.05% titanium. The alloy is heat treated to T6 conditions that represent 64 ksi tensile strength, 58 Ksi yield strength, 7% elongation and a Hbn of 135- Aluminum drillpipe generally comes with steel tool joints that are threaded on to ensure maximum strength that cannot be attained with aluminum joints. 

The special high-purity zinc (99-99%) is used mainly for the production of diecasting alloys containing 4% aluminium and 0 -04% magnesium and some-times I % copper, as shown in Table 4.30, which gives the composition of the two alloys laid down by BS 1004 1972, and of some newer zinc alloys. 

Let us first consider, as an example, the copper-zinc system of alloys.1 The ordinary yellow brass of commerce is restricted in composition to the first (copper-rich) phase of the system. This phase, which has the face-centered cubic structure characteristic of copper, is followed successively, as the zinc content is increased, by the /3-phase (body-centered cubic),... 

Fig. 7. Alloy composition versus (a) the shift in the aluminum deposition potential, AEai and (b) the shift in the copper/zinc deposition potential Ai cu,Zn, for the deposition of fee Cu-Al and hep Zn-Al alloys, calculated by using Eq. (12) and Eq. (13) and the free energy curves from Figure 6. Reproduced from Stafford et al. [104] by permission of The Electrochemical Society.

The main goal of this study was to identify different copper alloy compositions and relate them to different foundries or casting techniques. When considering the tin and the zinc contents in the sculptures, three different groups... 

The dependence of the Ms temperature of copper-zinc-aluminum alloys on composition. The dots indicate alloys for which the Ms has been measured. Data from D. E. Hodgson, M. H. Wu, and R. J. Biermann, Shape Memory Alloys, Johnson Matthey, http //www.jmmedical.com/html/. shape.memory.alloysJitml (accessed May 6, 2006). 

Figure 20.3 shows that increased amounts of both aluminum and zinc lower the Ms temperatures of copper-zinc-aluminum alloys. For both aluminum and zinc, determine ATI Ac where T is the Ms temperature and c is the atomic % solute. Note that the compositions in Figure 20.3 are in wt. %. 

It should not be assumed that the composition of commercial alloys will necessarily correspond to the percentages indicated or that other metals may not be present in small amounts. For example, the properties of brass differ with variation in the copper-zinc ratio. Similarly, the properties of commercial brass are often profoundly changed by the presence of small quantities of other metals. Since alloys are usually fabricated from metals that have not been subjected to elaborate purification processes, the resulting alloys are frequently contaminated with metals present in the primary ores. 

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