Solid solution of iron

TABLE 18.11. Enthalpies of Solutions of Pure Solids and Solid Solutions of Iron and Magnesium Silicates... 

At 1600° C. platinum effects the reduction of both ferric oxide and ferrosoferric oxide in air, oxygen being evolved and a solid solution of iron in platinum remaining as residue. The same reaction obtains at lower temperatures, namely, at 1200° C., if the oxygen pressure is very small. This explains why platinum crucibles sometimes increase in weight when used to heat oxides of iron at high temperatures.2... 

White and Enrschbraun (loc. c%t.) suggest that this nitride may be a solid solution of iron nitride in iron, namely,... 

Q Steel is one of the most important everyday materials which depend on the interstitial solid solution of iron with carbon. Although iron exists in three polymorphs, two body-centred cubic and one face-centred cubic, only one of these forms readily absorbs... 

The process of ethane oxidative chlorination imposes heavy demands on the catalysts. The conventional salt supported catalysts are composed of Cu, K, Ca, Mn, Co, Fe, Mg, and other metal chlorides containing various additives these salts are precipitated on alumina, zeolites, silica gel, and other supports. Catalytic systems that represent solid solutions of iron cations in the lattice of the a-A Oa and a-Ct203 phases doped with cations, such as K, Ba, Ce, and Ag are also known [7]. 

Solid solutions of iron in /5-Mn are paramagnetic at room temperature. Iron substitutes at both types of site in the structure, and shows no more than a slight quadrupole broadening [40]. Additional broadening at 4-2 K for... 

Complex oxides and their solid solution of irons... 

Figure 11.9 shows that the hardness of martensite increases rapidly with carbon content. This, again, is what we would expect. We saw in Chapter 8 that martensite is a supersaturated solid solution of C in Fe. Pure iron at room temperature would be b.c.c., but the supersaturated carbon distorts the lattice. 

Finally, at even lower transformation temperatures, a completely new reaction occurs. Austenite transforms to a new metastable phase called martensite, which is a supersaturated solid solution of carbon in iron and which has a body-centred tetragonal crystal structure. Furthermore, the mechanism of the transformation of austenite to martensite is fundamentally different from that of the formation of pearlite or bainite in particular martensitic transformations do not involve diffusion and are accordingly said to be diffusionless. Martensite is formed from austenite by the slight rearrangement of iron atoms required to transform the f.c.c. crystal structure into the body-centred tetragonal structure the distances involved are considerably less than the interatomic distances. A further characteristic of the martensitic transformation is that it is predominantly athermal, as opposed to the isothermal transformation of austenite to pearlite or bainite. In other words, at a temperature midway between (the temperature at which martensite starts to form) and m, (the temperature at which martensite... 

Austenite the y-modification of iron, having an f.c.c. lattice, which is stable above about 700°C the term is also applicable to solid solutions of carbon, chromium, nickel, etc. in y-iron. 

Ferrite the body-centred cubic form of iron (a-iron) and the solid solutions of one or more elements in b.c.c. iron. 

NOTE Steel consists of ferrite and pearlite phases. Ferrite is a solid solution of carbon in iron, whereas pearlite is a mixture of ferrite and laminar cementite. Cementite is a carbide, such as ferric carbide (Fe3C), although part of the iron content may be replaced by other metals including molybdenum. 

A type of iron or steel exhibiting a needle-like microstructure of solid solution of supersaturated carbon. 

A second way for a solid to accommodate a solute is interstitially, with solute atoms fitting in between solute atoms in the crystal stmcture. An important alloy of this type is carbon steel, a solid solution of carbon in iron, also shown in Figure 12-4. Steels actually are both substitutional and interstitial alloys. Iron is the solvent and carbon is present as an interstitial solute, but varying amounts of manganese, chromium, and nickel are also present and can be in substitutional positions. 

So, in the latter case the apparent activation energy is increased by the heat of adsorption of CO, amounting to about 40-60 kJ/mol as calculated from the IR experiments. Hence, for both the Co and the Cu samples E is slightly larger than 2 (table 2) while for iron ai is considerably lower. All these values are compatible with values reported in the literature for Fe-zeolites [6,7,10,11] or dilute solid solutions of Co in MgO [31]. The kinetic and IR results with NO indicate that, like CO, it can remove the oxygen from the... 

Zinc, Cu and Ni have similar ionic radii and electron configurations (Table 5.6). Due to the similarity of the ionic radii of these three metals with Fe and Mg, Zn, Cu and Ni are capable of isomorphous substitution of Fe2+ and Mg2+ in the layer silicates. Due to differences in the electronegativity, however, isomorphous substitution of Cu2+ in silicates may be limited by the greater Pauling electronegativity of Cu2+ (2.0), whereas Zn2+ (1.6) and Ni2+ (1.8) are relatively more readily substituted for Fe2+ (1.8) or Mg2+ (1.3) (McBride, 1981). The three metals also readily coprecipitate with and form solid solutions in iron oxides (Lindsay, 1979 Table 5.7). 

Austenite Solid solution of carbon in gamma iron (fee), with up to about 8% of the available sites occupied by C atoms... 

Ferrite Solid solution of carbon in alpha iron (bcc). 

Figure 6 illustrates a more complicated situation. The sample was a plain iron-carbon steel—an iron foil carburized to about 5 atomic % carbon and then quenched. One sees a rather complex pattern. There is a large central peak from some untransformed high temperature face-centered phase of iron containing carbon in solid solution, retained austenite. There is a strong six-line pattern coming from martensite, a distorted body-centered solid solution of carbon in iron. We also see a... 

A similar departure from the diffusion law to the logarithmic is likewise to be noted when the oxide formed is not of uniform composition but consists of a solid solution of two oxides such as obtains in the case of iron. 

Carbon is soluble to varying degrees in each of these allotropic forms of iron. The solid solutions of carbon in a-Fe, y-Fe, and <5-Fe are called, respectively, ferrite, austenite, and 8-ferrite. So, for example, the single-phase region labeled as y in... 

A 600-ml Parr reactor was charged with 5 ml toluene and 4.2 ml of 13.5 wt% toluene solution of methylaluminoxane. This was sequentially treated with a zirconium complex (2.0 mg) dissolved in 2 ml toluene, 0.1 wt% toluene solution of iron biphenyl derivative (433 mg), 30 ml 5-ethylidene-2-norbomene, and 120 ml 2,2,4-trimethyl-pentane. The autoclave was sealed and heated to 65°C and then pressurized with ethylene to 1.24 MPa. The reaction mixture was heated to 90°C for 2 hours, cooled to ambient temperature, and vented. The mixture was slowly poured into 400 ml of methanol and then treated with 6 ml of 12 M hydrochloric. It was stirred for 25 minutes at ambient temperature, filtered, washed with methanol six times, and 3.06 g of product isolated as a white powdery solid. 

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