Journal ArticleDOI
On the microstructure of rapidly solidified Al-15 wt pct mn ribbons: effect of annealing in the temperature range 300° to 600 °C
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In this paper, a study of the relationship between the microstructures formed in rapidly solidified Al-15 wt pct Mn ribbons and the precipitation processes following annealing in the regime 300° to 600 °C from 15 minutes to 100 hours was made.Abstract:
A study has been made of the relationship between the microstructures formed in rapidly solidified Al-15 wt pct Mn ribbons and the precipitation processes following annealing in the regime 300° to 600 °C from 15 minutes to 100 hours. The as-melt spun ribbons exhibit the icosahedral structure (in an Al-matrix), which is found to be stable up to ∼320 °C as deduced from electrical resistivity measurements. X-ray and TEM analyses reveal that decomposition of this phase is detectable after annealing at 400 °C/1 h, giving rise to Al6Mn. At 450 °C, four phases, viz., the G, Al6Mn, G’, and G″ intermetallic phases, are observed (in addition to Al), which result from the direct decomposition of the icosahedral phase. At higher temperatures, only the Al6Mn phase + Al is observed. The effect of increase in annealing time is simply to coarsen the Al6Mn particles. Our X-ray and electron diffraction data favor the model proposed by Shechtman and Blech for the icosahedral structure. The investigations were carried out using density and electrical resistivity measurements, differential thermal analysis, as well as X-ray diffraction and optical and transmission electron microscopy.read more
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Quasicrystals, crystals and multiple twins in rapidly solidified Al-Cr-Si, Al-Mn-Si and Al-Mn-Cr-Si alloys
A. K. Srivastava,S. Ranganathan +1 more
TL;DR: In this paper, the icosahedral point group symmetry is linked to the point-group symmetry in cubic crystalline aggregates and the occurrence of multiple twinning around an irrational axis of the RAS is reported in an aggregate of fine size cubic crystallites in all three alloys.
Journal ArticleDOI
Dodecahedral-shaped quasicrystalline precipitates in dilute Al-Mn solid solutions
TL;DR: In this article, the Al-Mn icosahedral phase was found to precipitate and grow at room temperature from rapidly quenched Al-4 at % Mn f.c.c., with the composition 13•5 ± 1•5 at.%Mn, the surrounding matrix having a composition 3•1 ± 0•3 at.
Journal ArticleDOI
Structure and decomposition behaviour of rapidly solidified AI-Cu-Li-Mg-Zr alloys
D. H. Kim,R. Cantor,H. I. Lee +2 more
TL;DR: The microstructural characteristics of AI-Cu-Li-Mg-Zr alloys have been studied after rapid solidification by melt spinning and after subsequent annealing at temperatures in the range 160 to 500°C, by using a combination of optical microscopy, scanning and transmission electron microscopy and X-ray diffraction, differential scanning calorimetry and microhardness measurements.
Journal ArticleDOI
Self-annealing of rapidly solidified deposit layers of FeCSi alloys by flame spraying
TL;DR: In this article, the cooling rate of the flattened metal droplets during solidification is almost independent of the substrate temperature and the decomposition of metastable austenite and a metastable h.p. ϵ phase formed on rapid solidification start to decompose during spraying.
References
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Journal ArticleDOI
Metallic Phase with Long-Range Orientational Order and No Translational Symmetry
TL;DR: In this article, a metallic solid with long-range orientational order, but with icosahedral point group symmetry, which is inconsistent with lattice translations, was observed and its diffraction spots are as sharp as those of crystals but cannot be indexed to any Bravais lattice.
Journal ArticleDOI
Phenomenological theory of icosahedral incommensurate ("quasiperiodic") order in Mn-Al alloys
TL;DR: The crystal structure with icosahedral point-group symmetry and long-range orientational order observed by Shechtman et al. in Mn-Al alloys can be explained as a multiple-q density-wave structure with only one length scale.
Journal ArticleDOI
The microstructure of rapidly solidified Al 6 Mn
Dan Shechtman,I. A. Blech +1 more
TL;DR: In this article, the microstructure of rapidly solidified Al−Mn alloys containing 18 to 25.3 wt pct Mn was studied by transmission electron microscopy.
Journal ArticleDOI
Aluminum—1. A review of resistive mechanisms in aluminum
TL;DR: In this article, the effect of phonons, electron-electron interactions, boundaries, vacancies and interstitials, chemical impurities, dislocations, and stacking faults on the electrical resistivity of aluminum at room temperature and below are reviewed.