Phase diagrams for iron

Fig. 11. Solid solution phase diagram for iron/carbon.

Zhu] Zhukov, A.A., Phase Diagram for Iron-Carbon and Iron-Carbon-Silicon Alloys , Russ. J. 

Heat Treatment of Steel. Steels are alloys having up to about 2% carbon in iron plus other alloying elements. The vast application of steels is mainly owing to their ability to be heat treated to produce a wide spectmm of properties. This occurs because of a crystallographic or aHotropic transformation which takes place upon quenching. This transformation and its role in heat treatment can be explained by the crystal stmcture of iron and by the appropriate phase diagram for steels (see Steel). 

Abstract In the beginning, the mixed potential model, which is generally used to explain the adsorption of collectors on the sulphide minerals, is illustrated. And the collector flotation of several kinds of minerals such as copper sulphide minerals, lead sulphide minerals, zinc sulphide minerals and iron sulphide minerals is discussed in the aspect of pulp potential and the nature of hydrophobic entity is concluded from the dependence of flotation on pulp potential. In the following section, the electrochemical phase diagrams for butyl xanthate/water system and chalcocite/oxygen/xanthate system are all demonstrated from which some useful information about the hydrophobic species are obtained. And some instrumental methods including UV analysis, FTIR analysis and XPS analysis can also be used to investigated sulphide mineral-thio-collector sytem. And some examples about that are listed in the last part of this chapter. 

We can start, as did the ancient craftsmen, with the fusion of the iron oxide, FeO, with silica, SiO . The phase diagram for those binary mixtures show that whereas Si02 fuses at about 1713 C and FeO at 13 9 C, mixtures containing between 20 and 40 weight percent FeO fuse below 1250 C. Complexing with additions of another iron oxide, Fe203, in amounts of up to 10%, can lower the fusion temperature to about 1150 C. 

Table 2.1 lists equilibrium ratios for the reduction of selected metal oxides [4], while Figure 2.2 provides a complete phase diagram for the reduction of iron oxide at different temperatures [3, 5], In order to reduce bulk iron oxide to metallic iron at 600 K, the water content of the hydrogen gas above the sample must be below a few percent, which is easily achieved. However, in order to reduce Cr2C>3, the water content should be as low as a few parts per billion, which is much more difficult to realize. The data in Table 2.1 also illustrate that, in many cases, only partial reduction to a lower oxide may be expected. Reduction of Mn2C>3 to MnO is thermodynamically allowed at relatively high water contents, but further reduction to manganese is unlikely. 

Alloys are prepared commercially and in the laboratory by melting the active metal and aluminum in a crucible and quenching the resultant melt which is then crushed and screened to the particle size range required for a particular application. The alloy composition is very important as different phases leach quite differently leading to markedly different porosities and crystallite sizes of the active metal. Mondolfo [14] provides an excellent compilation of the binary and ternary phase diagrams for aluminum alloys including those used for the preparation of skeletal metal catalysts. Alloys of a number of compositions are available commercially for activation in the laboratory or plant. They include alloys of aluminum with nickel, copper, cobalt, chromium-nickel, molybdenum-nickel, cobalt-nickel, and iron-nickel. 

Figure 2 Phase diagram for the iron/oxygen system...

Figure 3.10. The equilibrium phase diagram for the iron-carbon system.

The complex binary phase diagram for the Fe-C system is shown in Figure 3.10, and illustrates a number of important transitions. In particular, as the temperature is increased from ambient to its melting point, pure iron exhibits a variety of allotropic changes. At room temperature, the ferrite form is most stable conversion to austenite... 

Figure 6 Phase diagram of iron-light-element alloys or compounds at high pressure and temperature (data for FeO are from Fei and Mao (1994) for Fe-Si alloy containing 7.9 wt.% silicon with a comparison to pure iron are from Lin et al. (2002b) for FeS are from Fei et al. (1995)).

Figure 7.19 Phase III Features of Interest Spider Diagram for iron(III) chloride...

Figure 25.1 The iron-caibon phase diagram for low concentrations of carbon.

In a one-component, or unary, system, only one chemical component is required to describe the phase relationships, for example, iron (Fe), water (H2O) or methane (CH4). There are many one-component systems, including all of the pure elements and compounds. The phases that can exist in a one-component system are limited to vapour, liquid and solid. Phase diagrams for one-component systems are specified in terms of two variables, temperature, normally specified in degrees centigrade,... 

Fig. 5 Na-Fe-S-O-phase diagram for prediction of corrosion of iron in a Na2S04 melt at 1200 K.

In the Pourbaix diagram for iron, Fig. 4.2, the vertical line at pH 1.76 represents the equilibrium reaction, 2Fe + 3H2O Fe203 + 6H+. To the right of this line (i.e., at pH > 1.76), Fe203 is the stable phase and this oxide, as a protective film, would be expected to provide some protection against corrosion. To the left of this line (i.e., at pH < 1.76), ferric ions in solution are stable, and corrosion is expected to take place without any protection afforded by a surface oxide film. 

Kozl] Kozeschnik, E., Vitek, J.M., Ortho-Equilibrium and Para-Equilibrium Phase Diagrams for Interstitial/Substitutional Iron Alloys , Calphad, 24(4), 495-502 (2000) (Phase Diagram, Phase Relations, Thermodyn., Calculation, 10)... 

Par] Paiameswaian, K., Metz, K., Morris A., Phase Equilibria for Iron rich Fe-Cu-C Alloys 1500 to 950°C , Metall Trans, lOA, 1929-1939 (1979) (Experimental, Morphology, Phase Diagram, Phase Relations, 41)... 

Bla] Blanchard, J.R., Parke, R.M., Herzig, A.J., Constitution Diagrams for Iron-Carbon-Molybdenum Alloys , Trans. ASM, 27, 697-718 (1939) (Experimental, Phase Diagram, Meehan. Prop., 13)... 

Paris), 6(12), 104-161 (1951) (Crys. Sfructure, ExperimentaL Magn. Prop., Review, 66) [1955Sam] Samuel, R, Finch, L.G., Rait, J.R., A Phase Diagram for I per Cent Carbon-Iron Alloys Containing up to 16 % Nickel , Nature, 175, 37-38 (1955) (ExperimentaL Phase Diagram, Phase Relations, 4)... 

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