In the Al-Fe binary system, the Al₁₃Fe₃ phase as well as the Al₁₃Fe₄ phase has similar icosahedral building blocks like those appearing in quasicrystals. Therefore, it is of vital importance to clarify the formation process of these two phases. Coexistence of the Al₁₃Fe₃ and Al₁₃Fe₄ phases was discovered from the educts obtained with a nominal atomic ratio of Al/Fe of 9:2 by high-pressure sintering for the first time. Firstly, single crystal X-ray diffraction (SXRD) combined with a scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDX) measurement capabilities were adopted to determine the detailed crystal structures of both phases, which were sharply refined with regard to Al₁₃Fe₃ and Al₁₃Fe₄. Secondly, the orientation relationship between Al₁₃Fe₃ and Al₁₃Fe₄ was directly deduced from the SXRD datasets and the coexistence structure model was consequently constructed. Finally, seven pairs of parallel atomic planes and their unique orientation relations were determined from the reconstructed reciprocal space precession images. In addition, the real space structure model of the intergrowth crystal along with one kind of interfacial atomic structure were constructed from the determined orientation relations between two phases.

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 Al_12.48Fe_6.52 and Al_5.72Fe₂, 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.

SCIEPublish is an international open-access journal publishing service provider run by SCIE Publishing Limited, dedicated to supporting and inspiring scientists or institutions/societies who aspire to publish high-quality journals.

Single crystals of the intermetallic phase with composition Ti₄Ni₂C were serendipitously obtained by high-pressure sintering of a mixture with initial chemical composition Ti₂Ni. The Ti₄Ni₂C phase crystallizes in the Fd\overline{3}m space group and can be considered as a partially filled Ti₂Ni structure with the C atom occupying an octahedral void. Ti₄Ni₂C is isotypic with Ti₄Ni₂O, Nb₄Ni₂C and Ta₄Ni₂C, all of which were studied previously by means of powder diffraction.

Three B2-type intermetallic AlFe_{1 – δ} phases (0.18 < δ < 0.05) in the Al–Fe binary system were synthesized by smelting and high temperature sintering methods. The exact crystal structure for δ = 0.05 was refined by single-crystal X-ray diffraction. The amount of vacancy defects at the Fe atom sites was obtained by refining the corresponding site occupancy factor, converging to the chemical formula AlFe_0.95, with a structure identical to that of ideal AlFe models inferred from powder X-ray or neutron diffraction patterns.

A CaCu_1.424Fe_0.576Si₂ phase was obtained during high-pressure sintering of an Si-rich quasicrystal composition prealloy with the nominal chemical composition Si₆₁Cu₃₀Ca₇Fe₂. The obtained phase crystallizes in the space group I4/mmm (No. 139), with a = b = 4.041 Å and c = 10.010 Å. It is isotypic with CaCu₂Si₂ (a = b = 4.06 Å and c = 9.91 Å) [Palenzona et al. (1986). J. Less-Common Met. 119, 199–209] and CaFe₂Si₂ (a = b = 3.94 Å and c = 10.19 Å) [Hlukhyy et al. (2012). Z. Anorg. Allg. Chem. 638, 1619–1619]. It features a co-occupancy of Cu and Fe atoms with a ratio of the refined site-occupancy factors of 0.71 (15):0.29 (15).