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Structural Features of Al–Hf–Sc Master Alloys

  • Physical Metallurgy and Heat Treatment
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Russian Journal of Non-Ferrous Metals Aims and scope Submit manuscript

Abstract

Microstructural features of new master alloys of the Al–Hf–Sc system with metastable aluminides with a cubic lattice identical to the lattice of a matrix of aluminum alloys are investigated using optical microscopy, scanning electron microscopy, and electron probe microanalysis. Binary and ternary alloys are smelted in a coal resistance furnace in graphite crucibles in argon. Alloys Al–0.96 at % Hf (5.98 wt % Hf) and Al–0.59 at % Hf (3.77 wt % Hf) are prepared with overheating above the liquidus temperature of about 200 and 400 K, respectively. Alloys are poured into a bronze mold, the crystallization rate in which is ~103 K/s. Metastable Al3Hf aluminides with a cubic lattice are formed only in the alloy overheated above the liquidus temperature by 400 K. Overheating of ternary alloys, in which metastable aluminides Al n (Hf1–xSc x ) formed, is 240, 270, and 370 K. Depending on the Hf-to-Sc ratio in the alloy, the fraction of hafnium in aluminides Al n (Hf1–xSc x ) varies from 0.46 to 0.71. Master alloys (at %) Al–0.26Hf–0.29Sc and Al–0.11Hf–0.25Sc (wt %: Al–1.70Hf–0.47Sc and Al–0.75Hf–0.42Sc) have a fine grain structure and metastable aluminides of compositions Al n (Hf0.58Sc0.42) and Al n (Hf0.46Sc0.54), respectively. Sizes of aluminides do not exceed 12 and 7 μm. Their lattice mismatch with a matrix of aluminum alloys is smaller than that for Al3Sc. This makes it possible to assume that experimental Al–Hf–Sc master alloys manifest a high modifying effect with their further use. In addition, the substitution of high-cost scandium with hafnium in master alloys can considerably reduce the consumption of the latter.

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Authors and Affiliations

  1. Institute of Metallurgy, Ural Branch, Russian Academy of Sciences, Yekaterinburg, 620016, Russia

    E. A. Popova, P. V. Kotenkov, A. B. Shubin & E. A. Pastukhov

  2. Ural Federal University, Yekaterinburg, Russia

    P. V. Kotenkov

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  1. E. A. Popova
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  2. P. V. Kotenkov
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  3. A. B. Shubin
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  4. E. A. Pastukhov
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Correspondence to E. A. Popova.

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Original Russian Text © E.A. Popova, P.V. Kotenkov, A.B. Shubin, E.A. Pastukhov, 2017, published in Izvestiya Vysshikh Uchebnykh Zavedenii, Tsvetnaya Metallurgiya, 2017, No. 5, pp. 69–74.

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Popova, E.A., Kotenkov, P.V., Shubin, A.B. et al. Structural Features of Al–Hf–Sc Master Alloys. Russ. J. Non-ferrous Metals 58, 639–643 (2017). https://doi.org/10.3103/S1067821217060086

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  • DOI: https://doi.org/10.3103/S1067821217060086

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