Orientation Relationship of Intergrowth Al2Fe and Al5Fe2 Intermetallics Determined by Single-Crystal X-ray Diffraction

Abstract

Although the Al2Fe phase has similar decagonal-like atomic arrangements as that of the orthorhombic Al5Fe2 phase, no evidence for intergrowth samples of Al2Fe and Al5Fe2 has been reported. In the present work, the co-existence of Al2Fe and Al5Fe2 phases has been discovered from the educts obtained with a nominal atomic ratio of Al:Fe of 2:1 by arc melting. First, single-crystal X-ray diffraction (SXRD) as well as scanning electron microscope (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX) measurements have been utilized to determine the exact crystal structures of both phases, which are refined to be Al12.48Fe6.52 and Al5.72Fe2, respectively. Second, the orientation relationship between Al2Fe and Al5Fe2 has been directly deduced from the SXRD data sets, and the co-existence structure model has been constructed. Finally, four pairs of parallel atomic planes and their unique orientation relations have been determined from the reconstructed reciprocal-space precession images of (0kl), (h0l), and (hk0) layers. In addition, one kind of interface atomic structure model is constructed by the orientation relations between two phases, correspondingly.

Orientation Relationship of the Intergrowth Al13Fe3 and Al13Fe4 Intermetallics Determined by Single-Crystal X-ray Diffraction

“…However, the orientation relationship between Al 13 Fe 4 and Al 5 Fe 2 has only very recently been reported by Chatelier et al as far as we know using surface X-ray diffraction [51]. The orientation relationship between Al 2 Fe and Al 5 Fe 2 has been studied very recently by our group [52]. However, there are no related works on the orientation relationship between Al 13 Fe 3 and Al 13 Fe 4 , to the best of our knowledge, possibly due to the Al 13 Fe 3 phase not having been discovered until 2018 by our group [29].…”

“…The matrix method involves determining the conversion correlation between the crystal plane index and the crystal direction index of two phases through mathematical analysis. A detailed description of the matrix method can be found in our group's prior research [52]. The conversion matrix between the seven orientation relationships can be obtained using this method, as demonstrated in Table 5 below, where matrix A represents the conversion matrix between crystal planes, and matrix B represents the conversion matrix between crystal directions.…”