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Journal of Physical Studies 23(4), Article 4602 [8 pages] (2019)
DOI: https://doi.org/10.30970/jps.23.4602 STRUCTURAL STUDY OF LIQUID AND AS-QUENCHED AlFeSi ALLOYSO. S. Muratov{1}, V. P. Kazimirov{1}, O. S. Roik{1}, O. M. Yakovenko{1}, V. E. Sokolskii{1}, Т. М. Міkа {2}, Ya. О. Kashirina{1}, S. M. Galushko{3}
{1} Taras Shevchenko National University of Kyiv, |
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The short-range order in the liquid Al$_{70}$Fe$_{10}$Si$_{20}$, Al$_{70}$Fe$_{14}$Si$_{16}$, Al$_{76}$Fe$_{14}$Si$_{10}$ and Al$_{82}$Fe$_{14}$Si$_{4}$ alloys at 50-250$^\circ$C above the liquidus temperature has been studied by X-ray diffraction using MoK$\alpha$ radiation. The structure factors ($S(Q)$) and pair correlation functions ($g(r)$) were calculated from the scattering intensity according to the Faber-Ziman definition. The structure models of the investigated ternary alloys were reconstructed from experimental $S(Q)$ by means of the reverse Monte Carlo simulations. The analysis of the local atomic structure in RMC-models has been carried out using Voronoi-Delaunay diagrams. It has been shown that the structure of ternary Al-Fe-Si melts is determined mainly by the Al-Fe interactions. The Fe-Si interactions manifest themselves when the Si content increases. The replacement of Al by Si at transition from Al$_{82}$Fe$_{14}$Si$_{4}$ to Al$_{70}$Fe$_{14}$Si$_{16}$ liquid alloys leads to a reduction of the nearest-neighbour distance ($R_1$). On the experimental ($S(Q)$) and partial ($S_{\rm FeFe}(Q)$) structure factor curves of the liquid alloys a prepeak has been observed. The prepeak is the evidence of the medium-range order caused by the specific arrangement of Fe-centered atomic clusters. The real-space structural correlations ($R_p$) between these clusters are estimated to be in the range of 5.2 to 5.5 \AA\ and the correlation length ($L$) is from 10 to 16 \AA. The $S(Q)$ curves of the investigated ternary melts are characterized by the asymmetric shape of the second peak that is associated with an icosahedral short-range order in polytetrahedral clusters. It was discovered that an amorphous phase and a nanocrystalline Al phase have been formed in the melt-spun Al$_{70}$Fe$_{10}$Si$_{20}$ alloy. The annealing of the melt-spun Al$_{70}$Fe$_{10}$Si$_{20}$ ribbons causes the formation of $\beta$-Al$_{4,5}$FeSi and Si crystal phases.
PACS number(s): 61.05.cp, 61.20.-p, 61.20.Ja, 61.25.Mv, 61.43.Dq