Crystallization behavior of two Al-Ni-Co-Gd amorphous alloys with selected Ni/Co ratios

•Phase transformations in Al-based RE (rare-earth) containing alloys.•Short range reordering from amorphous matrix.•Scanning electron nano-beam diffraction revealing stacking disorder.•Al4Gd, Al4RE, I4/mmm to Imma transformation, Al19Gd3Ni5. [Display omitted] Metallic ribbons of Al86NixCoyGd6 compos...

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Veröffentlicht in:Journal of alloys and compounds 2021-09, Vol.876, p.160109, Article 160109
Hauptverfasser: Svec, Peter, Rusanov, Boris, Moroz, Anastasia, Petrova, Sofia, Janickovic, Dusan, Sidorov, Valeriy, Sr, Peter Svec
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Sprache:eng
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Zusammenfassung:•Phase transformations in Al-based RE (rare-earth) containing alloys.•Short range reordering from amorphous matrix.•Scanning electron nano-beam diffraction revealing stacking disorder.•Al4Gd, Al4RE, I4/mmm to Imma transformation, Al19Gd3Ni5. [Display omitted] Metallic ribbons of Al86NixCoyGd6 composition with different ratio of nickel and cobalt, (x/y = 1 and 3), were produced by standard planar flow casting method in amorphous state. Phase transformation follows upon heat treatment in 5 crystallization stages. Detailed microstructural characterizations (e. g. scanning electron diffraction experiments) were carried out to explain unusual phenomenon shown in x-ray diffraction data, calorimetric and complementary resistometry measurements bound to the second transformation stage. The observed phenomenon was proven to be connected to a observed reordering on the sub-nanometer scale without previous chemical rearrangement forming from amorphous matrix surrounding fcc-Al(Ni) nanocrystals, appearing as a second and single transformation step. Kinetics of crystallization was studied by differential scanning calorimetry and further monitored by electrical resistivity measurements. The transformation sequence up to 850 K is explained by X-ray diffraction and supported with detailed scanning transmission electron microscopy and energy dispersive spectroscopy observations.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2021.160109