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 |
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Hauptverfasser: | , , , , , , |
Format: | Artikel |
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. |
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ISSN: | 0925-8388 1873-4669 |
DOI: | 10.1016/j.jallcom.2021.160109 |