Iron alloy

The Fe-Al alloys are a good example of magnetically ordered alloys in [Refs, on p. 325] 

The internal magnetic field at a given iron atom in the disordered Fe-Al alloys is strongly dependent on the number of aluminium nearest neighbours 

The chemical isomer shift in Fe-Al alloys increases regularly with increase in Al nearest neighbours probably indicating transfer of electrons to the Fe 3d-band which would also cause the reduction in core polarisation observed 

The change in magnetic field relative to pure a-Fe for any given site, A//, 

Above 30 at. % the alloys are paramagnetic at room temperature, but the 50 at. % alloy gives a very narrow line because each Fe atom has 8 A1 

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Alloy cast irons. Alloy additions are made to cast irons to improve the properties for particular purposes. Alloy cast irons can be used in engineering applications where plain cast iron is unsuitable and may even replace steel for some components such as crankshafts. 

Marcus P, Teissier A and Oudar J 1984 The influence of sulfur on the dissolution and the passivation of a nickel-iron alloy. 1. Electrochemical and radiotracer measurements Corrosion Sc . 24 259... 

Recently, a method has been proposed to overcome the problems associated with calculating forces in both VMC and DMC [122], It has been suggested that the use of QMC in the near future to tackle the energetics of systems as challengmg as liquid binary iron alloys is not unthinkable [123],... 

Nickel is found as a constitutent in most meteorites and often serves as one of the criteria for distinguishing a meteorite from other minerals. Iron meteorites, or siderites, may contain iron alloyed with from 5 percent to nearly 20 percent nickel. Nickel is obtained commercially from pentlandite and pyrrhotite of the Sudbury region of Ontario, a district that produces about 30 percent of the world s supply of nicke. 

A series of nickel—chromium—iron alloys based on the soHd solution Inconel 600 alloy (see Table 4) was developed, initially depending on aluminum ... 

Soft magnetic materials are characterized by high permeabiUty and low coercivity. There are sis principal groups of commercially important soft magnetic materials iron and low carbon steels, iron—siUcon alloys, iron—aluminum and iron—aluminum—silicon alloys, nickel—iron alloys, iron-cobalt alloys, and ferrites. In addition, iron-boron-based amorphous soft magnetic alloys are commercially available. Some have properties similar to the best grades of the permalloys whereas others exhibit core losses substantially below those of the oriented siUcon steels. Table 1 summarizes the properties of some of these materials. 

Table 1. Magnetic Properties of Fully Annealed Iron and Iron Alloys ...

Iron—Aluminum and Iron—Aluminum—Silicon Alloys. The influence of aluminum on the physical and magnetic properties of iron is similar to that of silicon, ie, stabilization of the bcc phase, increased resistivity, decreased ductility, and decreased saturation magnetization, magnetocrystalline anisotropy, and magnetostriction. Whereas Si—Ee alloys are well estabHshed for electrical appHcations, the aluminum—iron alloys have not been studied commercially. However, small (up to ca 0.3%) amounts of A1 have been added to the nonoriented grades of siHcon steel, because the decrease in ductiHty is less with A1 than with Si. 

Chromium—Cobalt—Iron Alloys. In 1971, a family of ductile Cr—Co—Fe permanent-magnet alloys was developed (79). The Cr—Co—Fe alloys are analogous to the Alnicos in metallurgical stmcture and in permanent magnetic properties, but are cold formable at room temperature. Equivalent magnetic properties also can be attained with substantially less Co, thereby offering savings in materials cost. 

Vanadium—Cobalt-Iron Alloys. V—Co—Fe permanent-magnet alloys also are ductile. A common commercial ahoy, Vicahoy I, has a nominal composition 10 wt % V, 52 wt % Co, and 38 wt % Fe (Table 10). Hard magnetic properties are developed by quenching from 1200°C for conversion to bcc a-phase foUowed by aging at 600°C (precipitation of fee y-phase). The resulting properties are isotropic, with ca kJ/m ... 

The displacement mechanism involves placing the iron alloy packed in chiomium powder, NH Cl, and in a sealed retort, which is heated to... 

Nickel—Iron and Cobalt—Iron Alloys. Selenium improves the machinabifity of Ni—Ee and Co—Ee alloys which are used for electrical appfications. Neither sulfur nor tellurium are usefiil additives because these elements cause hot britdeness. The addition of 0.4—0.5% selenium promotes a columnar crystal stmcture on solidification, doubling the coercive force of cobalt—iron-titanium alloy permanent magnets produced with an equiaxial grain stmcture. 

The higher chromium—iron alloys were developed in the United States from the early twentieth century on, when the effect of chromium on oxidation resistance at 1090°C was first noticed. Oxidation resistance increased markedly as the chromium content was raised above 20%. For steels containing appreciable quantities of nickel, 20% chromium seems to be the minimum amount necessary for oxidation resistance at 1090°C. 

Silicon Reduction. The preparation of ferrovanadium by the reduction of vanadium concentrates with ferrosiUcon has been used but not extensively. It involves a two-stage process in which technical-grade vanadium pentoxide, ferrosiUcon, lime, and fluorspar are heated in an electric furnace to reduce the oxide an iron alloy containing ca 30 wt % vanadium but undesirable amounts of siUcon is produced. The siUcon content of the alloy is then decreased by the addition of more V2O5 and lime to effect the extraction of most of the siUcon into the slag phase. An alternative process involves the... 

Cobalt—molybdenum alloys are used for the desulfurization of high sulfur bituminous coal, and cobalt—iron alloys in the hydrocracking of cmde oil shale (qv) and in coalhquefaction (6). 

Uses. Copper—nickel—iron alloys, UNS C 96200 (90 10 copper nickel) and UNS C 96400 (70 30 copper nickel), are used in corrosion-resistant marine (seawater) appHcations. UNS C 96400 is used for corrosion-resistant marine elbows, flanges, valves, and pumps. Leaded nickel—brass, UNS C 97300 (12% nickel-silver), is used for hardware fittings, valves, and statuary and ornamental castings. 

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