Fe-Al alloys

Addition of Cr to Fe-Al alloys aids the formation of Cr sulphides and AI2S3 which together markedly reduce the sulphidation rate". Between 2% and 5% Cr then, more than 3% Al is required to obtain protection. At 9% Cr, however, only 1 % Al is needed to give protection since the Cr is sufficiently active to lower the S potential seen by Al (secondary gettering). Thus... 

Fig. 12.29 Aluminised steel. A AI2O3 + aluminium, B Fe-Al alloys and C steel X 75...

Allen reported TEM observations of a nonaligned decomposition products in long-range ordered Fe-Al alloy [22]. Such morphologies are called isotropic spinodal microstructures. Similar structures are observed in Al-Zn and Fe-Cr alloys. Such structures can be produced in systems that are elastically isotropic or in which the lattice constant does not change appreciably with composition. 

S.M. Allen. Phase separation of Fe-Al alloys with Fe3A1 order. Phil. Mag., 36(1) 181-192, 1977. 

Fig. 32a. Potentiodynamic polarization curve of rotating disc electrodes of Fe/Al alloys in phthalate buffer pH 5.0 with dE/dt = 20 mV s-1 [76],...

Fig. 32b. Composition of passive layers on Fe/Al alloys from ISS sputter depth profiles formed in phthalate buffer pH 5.0 at E = 1.0 V for 300 s [76],...

According to ARXPS, Fe(II) is located in the outer parts of the anodic oxide and remains trapped up to very positive potentials, especially in alkaline, but also weakly acidic electrolytes. Similar to the situation of Fe/Al alloys, its oxidation is prevented due to the poor conductivity of a large Si02 content at the metal surface, i.e. in the inner parts of the film [79]. Fe(II) oxidation requires electronic conductivity from the outer parts of the passive layer to the metal surface. 

Raney Pe.126,127 In this procedure 150 g of 20% Fe-Al alloy powder is added in small portions to a solution of sodium hydroxide (250 g per 1000 ml). The reaction is very vigorous, and 3 h is necessary for the addition. At the end, the temperature is held at 80-90°C until evolution of hydrogen ceases. The treatment with alkali is then repeated, after which the iron is washed repeatedly with boiling water by decantation. It is fully washed free of alkali with absolute alcohol and stored under alcohol. 

Enhancement (multiple excitation). If the primary radiation causes element B in the specimen to emit its characteristic radiation, of wavelength Ag, and if Ag is less than A. then fluorescent K radiation from A will be excited not only by the incident beam but also by fluorescent radiation from B. (This effect is evident in the Fe-Ni curve of Fig. 15-8. Ni Ka radiation can excite Fe Ka radiation, and the result is that the observed intensity of the Fe Ka radiation from an Fe-Ni alloy is closer to that for an Fe-Al alloy of the same iron content than one would expect from a simple comparison of the absorption coefficients of the two alloys. In the case of an Fe-Ag alloy, the observed Fe Ka intensity is much lower, even though Ag Ka can excite Fe Ka, because of the very large absorption in the specimen.)... 

Fig. 1. Calculated and experimental activity of aluminium in solid Ni-Al and Fe-Al alloys at 1000°C (after Steiner and Komarek [9]) dashed lines indicate measured values...

Figure 4.11. Cross section through an alumina crucible with Fe,Al alloy and AI.Oj whiskers. n typical orientation (magnification of whiskers 10x ) (71).

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... 

Fe-Al alloys are similar to Fe-Si alloys in some respects (high resistivity, hardness, permeability, loss). As with Si, addition of A1 prevents the transformation from occurring, and Fe-Al alloys can be... 

Mas] Masahashi, N., Semboshi, S., Konn, T.-J., Hanada, S., Effect of Pressiue Application on Microstructure Evolution in a Composite of Fe-Al Alloy and CrMo Steel , J. Alloy Compd., 413, 281-288 (2006) (Morphology, Phase Relations, Experimental, Mecham. Prop., Transport Phenomena, 16)... 

It is important to recognize that the ion current technique requires that measurements are taken at a series of compositions starting from a pure component at one side of the system. Some representative measurements from our laboratory on Fe-Al alloys are given in Figure 48.10 [90]. This is a very valuable technique and has been used extensively with binary alloys and even some ternary alloys [3,4,91,92]. 

NANOSIZED Fe-Al ALLOYS SYNTHESIZED BY HIGH-ENERGY BALL MILLING... 

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