Trace-element alloying additions

Trace elements which adversely affect intercrystalline attack are normally controlled at a safe level. Copper is particularly pertinent in this respect since relatively small additions can cause a marked increase in intercrystalline attack in some alloy systems (Sections 1.3 and 1.7). 

For the most part, the zinc materials recovered from secondary materials such as slab zinc, alloys, dusts, and compounds are comparable in quality to primary products. Zinc in brass is the principal form of secondary recovery, although secondary slab zinc has risen substantially over the last few years because it has been the principal zinc product of electric arc furnace (EAF) dust recycling. Impure zinc oxide products and zinc-bearing slags are sometimes used as trace element additives in fertilizers and animal feeds. About 10% of the domestic requirement for zinc is satisfied by old scrap. 

The reddish metal was already known in prehistoric times. It occasionally occurs as a native metal, but mostly in conspicuous green ores, from which it is extracted relatively easily. It is convenient to work, but not very hard. Not very optimal as a tool ("Otzi the Iceman" had a copper axe with him). Only through the addition of tin is the more useful bronze obtained. Its zinc alloy is the versatile and widely used brass. Copper is one of the coinage metals. Water pipes are commonly made of copper. Its very good thermal and electrical conductivity is commonly exploited (cable ), as well as its durability (roofs, gutters), as the verdigris (basic copper carbonate) protects the metal. Cu phthalocyanines are the most beautiful blue pigments. Seems to be essential to all life as a trace element. In some molluscs, Cu replaces Fe in the heme complex. A 70-kg human contains 72 mg. 

The main alloying elements of Al materials are Cu, Si, Mg, and Zn while Mn, Fe, Cr, and Ti are frequently present in small quantities, either as impurities or additives. Ni, Co, Ag, Li, Sn, Pb, and Bi are added to produce special alloys. Be, B, Na, Sr, and Sb may be added as important trace elements. AU of these elements affect the stracture and thus the properties of an alloy. The compositions of the more important aluminium materials are discussed below, using the relevant phase diagram. AU aUoying components are completely soluble in liquid aluminium if the temperature is sufficiently high. However, these elements have only limited solubility in soUd solution. Continuous soUd solubU-... 

Steels can be classified as either low alloy steels, which contain carbon as the principal alloying element or high alloy steels, which contain significant amounts of other elements to produce the desired properties. The low alloy steels can be subdivided into low carbon, medium carbon, and high carbon steels and each of these can be either plain carbon or can contain small quantities of Ni, Mn, Cr, and other elements. One of the effects of these additives is to modify the temperature and composition of the eutectoid in the Fe-FeaC system. Ti, Mo, Si, and W will raise the euctectoid temperature while Ni and Mn will lower it. All of the above will shift the eutectoid composition toward the Fe-rich side. Plain carbon steels may contain some Mn along with other trace elements. 

In materials analysis, laser ablation has been applied to almost all fields of modem materials. For glasses, high-purity optical materials (e.g. CaF2), ceramics, semi- and superconductors, polymers, high-purity metals and alloys, the heterogeneity of the material, trace element concentrations and elemental distributions have been measured. In addition, this method has been used for the investigation of trace element composition of concrete, radioactive waste and radioactive materials, the characterization of steel inclusions and the determination of the composition and thickness of layered systems. 

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