Alloys Alloying

Alnico alloys Alloys containing Al, Ni, Co and Fe. Used for permanent magnets. 

Alloy Alloy 20 Alloy 366 Alloy 48 Alloy 600 Alloy 690... 

Figure 10 presents the Curie temperature (T ) vs the TM-content (x) for Co- and Fe-based biaary alloys. Alloying rare-earth elements with small amounts of transition metals (x < 0.2) leads to a decrease ia Curie temperature. This is particularly obvious ia the Gd—Co system where it corresponds to a nonmagnetic dilution similar to that of Cu (41,42). This iadicates that TM atoms experience no exchange coupling unless they are surrounded by a minimum number j of other TM atoms. The critical number is j = 5 for Fe and j = 7 for Co. The steep iacrease of for Co-based alloys with x about 0.7 is based on this effect. 

Refiner Plates. The refiner plates have a constmction of the type shown in Figure 12. The plates are constmcted of hard steel alloys. Alloys of... 

Alloys. Alloys consist of two or mote elements of different vapor pressures and hence different evaporation rates. As a result, the vapor phase and therefore the deposit constantiy vary in compositions. This problem can be solved by multiple sources or a single rod- or wire-fed electron beam source fed with the alloy. These solutions apply equally to evaporation or ion-plating processes. 

As for storage tanks, stainless steel and lacquer-lined mild steel are suitable materials of constmction for pipe lines. For pumps, valves, etc, various alloys are suitable, including phosphor bronze, gun metal. Monel, stainless steel, and certain nickel steel alloys. Alloys with high proportions of ziac and tin together with copper and aluminum are not recommended. 

The gating and riseting system for cast aluminum bron2e is extremely important and must be arranged to iatroduce the metal quietly at the lowest portion of the mold. The alloys shrink well hence the gating and riseting must be well adapted to the particular casting. See Table 12 for properties of these alloys. Alloys C 95300, C 95400, and C 95500 are heat-treatable for iacreased mechanical properties and the last two should be temper-aimealed if used ia a corrosive environment. 

The stiffness of pure titanium can be increased slightly by alloying alloys such as Ti—6A1—4V may be specified for partial dentures requiring additional rigidity. Titanium appHances do not tarnish or corrode in the mouth, have no metallic taste, and are easy to clean because plaque and calculus do not adhere to them. The relatively low thermal conductivity of titanium (relatively close to that of tooth enamel) gives these appHances a seemingly natural feel in the mouth and minimises thermal sensitivity (175). 

Stainless Steel There are more than 70 standard types of stainless steel and many special alloys. These steels are produced in the wrought form (AISI types) and as cast alloys [Alloy Casting Institute (ACI) types]. Gener y, all are iron-based, with 12 to 30 percent chromium, 0 to 22 percent nickel, and minor amounts of carbon, niobium (columbium), copper, molybdenum, selenium, tantalum, and titanium. These alloys are veiy popular in the process industries. They are heat- and corrosion-resistant, noncontaminating, and easily fabricated into complex shapes. 

L erung./. alloy alloying. L erungs-bestandteil, m. alloy constituent. -Stahl, m. alloy steel, -zusatz, m. alloying addition. 

Copper/nickel alloys Alloys containing 5-30% Ni, used mostly in the wrought condition have a very good combination of properties. For optimum corrosion resistance, additions of 0-5-2 0% each of Fe and Mn are made. 

An interesting illustration of the effect that quite small alloying additions may sometimes have on anodic behaviour is seen in Fig. 4.27 from a comparison of the Ni-30Cu alloy Alloy 400 with its age-hardening variant Alloy K500, which contains 2-7% A1 and 0-6% Ti. The presence of these elements in the latter alloy is responsible for a well-defined passive region, whereas the former alloy shows only a slight tendency to passivate in acidic... 

Fig. 10.13 The effect of the Mn/Fe ratio on the performance of Al-Zn-In-Mn anode alloys. Alloy composition range Zn 4-0-4-6% In 0-020-0 029% Mn 0-004-0-35% Fe 0-06-0-30% (after Klinghoffer and Linder )...

Alloys—See also the specific alloys Alloys, aluminum-magnesium and zinc-magnesium, metallothermic... 

The holes in the close-packed structure of a metal can be filled with smaller atoms to form alloys (alloys are described in more detail in Section 5.15). If a dip between three atoms is directly covered by another atom, we obtain a tetrahedral hole, because it is formed by four atoms at the corners of a regular tetrahedron (Fig. 5.30a). There are two tetrahedral holes per atom in a close-packed lattice. When a dip in a layer coincides with a dip in the next layer, we obtain an octahedral hole, because it is formed by six atoms at the corners of a regular octahedron (Fig. 5.30b). There is one octahedral hole for each atom in the lattice. Note that, because holes are formed by two adjacent layers and because neighboring close-packed layers have identical arrangements in hep and ccp, the numbers of holes are the same for both close-packed structures. 

Replacing some of the nickel with iron produces a family of alltws with intermediate corrosion resistance between stainless steels and the Ni-Cr-Mo alloys. Alloys such as Incoloy 825 and Hastelloy G-3 and G-30 are in this family. Incoloy 825 has 40 percent Ni, 21 percent Cr, 3 percent Mo, and 2.25 percent Cu. Hastelloy G-3 contains 44 percent Ni, 22 percent Cr, 6.5 percent Mo, and 0.05 percent C maximum. These alloys have extensive applications in sulfuric acid systems. Because of their increased nickel and molybdenum contents they are more tolerant of chloride-ion contamination than are standard stainless steels. The nickel content decreases the risk of stress-corrosion cracking molybdenum improves resistance to crevice corrosion and pitting. Many of the nickel-based alloys are proprietary and are coverecf by the following specifications ... 

Nickel Alloys Alloy C-4 (16 Cr, 16 Mo, Balance Ni) and alloy C-276 (16 Cr, 16 Mo, 3.5 W, 5 Fe, balance Ni) have been used for closure seals on cryogenic gas cylinders because the alloys retain all their ductility down to -327°C (—557°F). The impact strength at liquid nitrogen temperatures is the same as that at room temperature. 

Fig. 9. Effect of CuSC>4 concentration on deposition rate and composition of Ni-Cu-P alloy. ( ), alloy (O), Ni ( ), Cu (A), P. Adapted from ref. 102.

Shi, J., T. Makoto, T. Hiroyuki, N. Kuriyama, and T. Sakai, Influence of carbon on electrode properties of V-Ti-Ni type hydrogen storage alloy, /. Alloys Compd., 293-295, 716-720,1999. 

Another main use is as an alloy with other metals when it will lower the melting point of the metals with which it is alloyed. Alloys of indium and silver and indium and lead have the ability to carry electricity better than pure silver and lead. 

Chapter 10 provides an exhaustive description of how these techniques can be applied to a large number of industrial alloys and other materials. This includes a discussion of solution and substance databases and step-by-step examples of multi-component calculations. Validation of calculated equilibria in multi-component alloys is given by a detailed comparison with experimental results for a variety of steels, titanium- and nickel-base alloys. Further selected examples include the formation of deleterious phases, complex precipitation sequences, sensitivity factor analysis, intermetallic alloys, alloy design, slag, slag-metal and other complex chemical equilibria and nuclear applications. 

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