Crystallography of aligned Fe-Al eutectoid

Abstract

By applying the Weissenberg technique to small pieces of duplex crystals of FeA1 and FeA12, produced by directional eutectoid decomposition, it has been found possible not only to establish the previously unknown unit cell parameters of FeA12, but also the orientation relationship between FeA1 and FeA12. The unit cell of FeAI 2 can be described as an A-centred pseudo-monoclinic cell with a = 7.594, b = 16.886, c = 4.863 A, a = 89.55 ° ,/3 = 122.62 ° and 7 = 90-43°. The orientation relationship between both phases was found to be: [100]FeA12 II [i ll]FeA1 and (002)FeA12 II (01])FeA1. This relationship was confirmed by texture goniometry of larger directionally decomposed eutectoid samples in which the cubic FeA1 phase was frequently found to be twinned.

Orientation relationship of eutectoid FeAl and FeAl2

“…In the present study, the orientation relationship, as determined previously by Bastin et al (1978) and Hirata et al (2008), will be confirmed and the supposed differences will be examined. In addition, the interface of the FeAl and FeAl 2 lamellae is investigated by means of local orientation determination and cross sectioning.…”

“…In addition, the interface of the FeAl and FeAl 2 lamellae is investigated by means of local orientation determination and cross sectioning. In contrast to the investigation of Bastin et al (1978), a distinct preferential interface can be identified. By applying the experimental data, the atomistic details of the relationship of the involved crystal structures are discussed.…”

Formation enthalpy of intermetallic phases from Al–Fe system measured with solution calorimetric method

“…In the second sample, apart from the Al 2 Fe, also Table 4 together with these obtained in Ref. [36,37] and the observed differences are lower than 1%. In the following step, the obtained phases were cut into small pieces suitable for using in the calorimeter.…”

Determination of the crystal structure of the ɛ phase in the Fe–Al system by high-temperature neutron diffraction

“…This is not surprising as the eutectoid formation/decomposition occurs as a spontaneous process not allowing long-range diffusion processes but only short-range rearrangements of the atoms. In addition it is well-known from the literature that there exist simple orientation relationships in the aligned lamellar microstructures between the phases FeAl and FeAl 2 [28].…”