The structure of decagonal Al70Ni15Co15

A stable decagonal quasicrystal with nominal composition Al 73 Ir 14.5 Os 12.5 has been grown from the aluminum-rich melt. It has an incongruent melting temperature of T m = 1283• C and does not transform into a periodic phase within the maximum applied annealing time of 8 weeks at 1000• C. The phase equlibria in the aluminum-rich part of the system Al-Ir-Os have been explored. The X-ray diffraction patterns can be indexed

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“…For an explanation of the terminology of the higher-dimensional approach used see Ref. [18] or, for a practical example, [26].…”

Section: D Structure Analysis By the Charge-flipping Methodsmentioning

confidence: 99%

New stable decagonal quasicrystal in the system Al–Ir–Os

Katrych

Weber

Kobas

et al. 2007

Journal of Alloys and Compounds

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“…A reduction of the particle size is expected for longer alloying time. However, an opposite effect is observed, this could be due to the high ductility, stability and structure of the decagonal phase of the system Ni-CoAl [18][19][20][21][22][23] , in addition to the forming a bimodal/multimodal grain size distribution, that improves the ductility of the nanostructured materials 24 .…”

Section: Resultsmentioning

confidence: 92%

Synthesis, Microstructural Characterization and Microhardness of AlCoNi-SiC Composite Prepared by Mechanical Alloying

et al. 2017

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Equiatomic AlCoNi alloy matrix were reinforced by the dispersion of SiC nanoparticles (SiCnp) using the mechanical alloying process. The metallic powders were milled for 10, 20 and 30 h and sintered at 1200 0C under vacuum. Through particle size distribution, X-ray diffraction and scanning electron microscopy investigations, the mechanically alloyed powders for 10 h were selected to be reinforced with SiCnp (2.5, 5 and 10 wt.%). The microstructural features, and improvement in microhardness and porosity of sintered AlCoNi-SiC composites were investigated as a function of SiCnp content. Microhardness Vickers test showed that the enhanced microhardness of the AlCoNi-SiCnp composite could be attributed to the decrease of porosity in comparison to the AlCoNi alloy.

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“…(viii) The final step in a structure refinement should be the calculation of par-space maximum-entropy maps (which are free from truncation effects) of the electron-density distribution function to identify shortcomings of the refined model structure (see, e.g., Steurer et al, 1993). Thereby the phases of the less well determined weak reflections should be allowed to vary.…”

Section: Open Questions and Challengesmentioning

confidence: 99%

“…Fig. 8 of Steurer et al (1993)]. Since the scaling symmetry only refers to the positions of atoms and not to their kind, the strongest peaks on a Patterson map will mark the intercluster vectors (Cervellino et al, 1998).…”

Section: The Penrose Tiling -A Proper Quasilattice Model For Real Qcs?mentioning

confidence: 99%

Quasicrystals: What do we know? What do we want to know? What can we know?

Steurer

2018

Acta Crystallogr A Found Adv

100

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More than 35 years and 11 000 publications after the discovery of quasicrystals by Dan Shechtman, quite a bit is known about their occurrence, formation, stability, structures and physical properties. It has also been discovered that quasiperiodic self-assembly is not restricted to intermetallics, but can take place in systems on the meso-and macroscales. However, there are some blank areas, even in the centre of the big picture. For instance, it has still not been fully clarified whether quasicrystals are just entropy-stabilized high-temperature phases or whether they can be thermodynamically stable at 0 K as well. More studies are needed for developing a generally accepted model of quasicrystal growth. The state of the art of quasicrystal research is briefly reviewed and the main as-yet unanswered questions are addressed, as well as the experimental limitations to finding answers to them. The focus of this discussion is on quasicrystal structure analysis as well as on quasicrystal stability and growth mechanisms.

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The structure of decagonal Al₇₀Ni₁₅Co₁₅

Cited by 216 publications

References 14 publications

New stable decagonal quasicrystal in the system Al–Ir–Os

New stable decagonal quasicrystal in the system Al–Ir–Os

Synthesis, Microstructural Characterization and Microhardness of AlCoNi-SiC Composite Prepared by Mechanical Alloying

Quasicrystals: What do we know? What do we want to know? What can we know?

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