One-dimensional quasi-crystals in the ternary system AlCuNi?

Tendeloo, Gustaaf Van; Heurck, C. Van; Amelinckx, S.

doi:10.1016/0038-1098(89)90070-7

Cited by 21 publications

(10 citation statements)

References 6 publications

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“…The vacancy ordered phases (VOPs) being an interesting class of intermetallic phases comes under the broad category of structures with ordered defects [2]. It has been shown that the vacancy ordered phase can be considered as an approximant phase to one-dimensional as well as two-dimensional decagonal quasicrystals [3][4][5]. VOPs represent a class of structure where compositions and diffraction effects display a close relationship with the golden mean,  (where, τ=1/2(5 +1).…”

Section: Introductionmentioning

confidence: 99%

Stability of mechanically alloyed vacancy ordered phase in Al₇₀Cu₁₅Ni₁₅alloy during annealing

Yadav¹,

Mukhopadhyay²,

Tiwari³

et al. 2010

J. Phys.: Conf. Ser.

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Abstract.A nano  3 vacancy-ordered phase in the Al-Cu-Ni alloy system has been synthesized with a composition close to Al 70 Cu 15 Ni 15 by mechanical alloying a mixture of elemental powder in a high-energy ball mill by varying milling time from 10 to 100 hours. The stability of nano-crystalline  3 vacancy-ordered phase has been studied under thermal annealing in vacuum as well as in air. The x-ray diffraction and transmission electron microscopy techniques were employed for characterization of the milled and annealed samples. The powder after 100 h of milling was found to contain mostly nano  3 phase with the partial ordering, and with crystallite sizes in the range of 10-20 nm along with a lattice strain of ~0.67 %. The milled powder, after annealing in vacuum at 700 ºC for 60 h, revealed the formation of a strain-free and ordered  3 phase with a crystallite size of 80 nm, indicating grain coarsening. It is interesting to note that the milled powder annealed in air at 700 ºC for 60 h showed the formation of (Cu,Ni)Al 2 O 4 type spinel phase with the lattice parameter of 8.1 Å and the lattice strain as 0.52 %. The average grain size of spinel phase was found to be ~ 40 nm.

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Section: Introductionmentioning

confidence: 99%

Stability of mechanically alloyed vacancy ordered phase in Al₇₀Cu₁₅Ni₁₅alloy during annealing

Yadav¹,

Mukhopadhyay²,

Tiwari³

et al. 2010

J. Phys.: Conf. Ser.

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“…However the structure of the latter phase, designated in the literature as a t-phase, is a not as simple as that of the b-AlCuFe studied in the present work. It presents a quasiperiodic vacancy order [10] and hence could bear a certain local resemblance with quasiperiodic or approximant phases.…”

Section: Discussionmentioning

confidence: 99%

Iron atomic jumps in Al–Cu–Fe quasicrystals and approximants

Brand

Hippert²

2008

Zeitschrift Für Kristallographie

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Abstract. The iron dynamics in the icosahedral quasicrystal i-AlCuFe and two cubic 1/1 approximants as well as the non-approximant cubic B2 phase has been studied by Mössbauer spectroscopy. In the i-phase the iron LambMössbauer recoilless fraction decreases below that predicted for lattice vibrations alone above about 550 K. This decrease is correlated with the onset of a quasielastic signal at high Doppler velocities, demonstrating local iron jump processes at temperatures above this point. In the two cubic approximants, a loss in the recoilless fraction also occurs above 550 K, revealing the same kind of Fe dynamics as in the i-phase but the effect is smaller. On the other hand, no anomalous Fe dynamics (other than lattice vibrations) is detected in the B2-AlCuFe phase. A comparison is made to literature Mössbauer and neutron scattering results in i-AlCuFe.

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“…Shastry et al (1980) reported the existence of a t 12 phase. van Tendeloo et al (1989) found t 18 , t 31 and t 38 and noted that 18 and 31 belong to non-standar d sequence 8, 5, 13, 18, 31, 49, . .…”

Section: …11 †mentioning

confidence: 99%

“…However, it is interesting to note that approximations to pentagonal and icosahedral structures in the B2 structure have been pointed out by Dong (1995Dong ( , 1996 and Dong et al (1999) who have explored reasons for regarding B2 structures as`approximants' to quasicrystals. Zhang and Kuo (1989) have observed that the ½ phases can occur in conjunction with decagonal quasicrystalline phases, with a surprising (and mysterious) orientation relation between the two phases: the tenfold axis and two perpendicular diads of the decagonal phase are aligned with [110], [001] and [11 10Š of the underlying B2 structure of the t phase.…”

Section: …31 †mentioning

confidence: 99%

Stacking sequences and symmetry properties of trigonal vacancy-ordered phases (τ phases)

Lord¹,

Ranganathan²,

Subramaniam³

2002

Philosophical Magazine A

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The vacancy-ordered phases known as t phases are described and the literature dealing with the observed stacking sequences is reviewed. It is shown that the stacking sequences along the threefold axis can be derived from a projection method involving projection on to an axis of type ‰rrq qŠ. The structure has alternating ®lled and empty lamellae parallel to planes of type …rrq q). The particular cases in which r and q are consecutive numbers of the Fibonacci sequence can be regarded as rational approximants to a onedimensional quasiperiodic structure. Some mathematical properties of the sequences, and their relationship with the three-dimensional structures, are presented. } 1. IntroductionThe vacancy-ordere d phases known as t-phases are B2 structures in which the vertices of one of the two constituent primitive cubic lattices are occupied by aluminium atoms and those of the other are occupied by transition-meta l atoms or are vacant sites. The (111) planes are either completely ®lled or completely empty, with characteristic periodic stacking sequences along the [111] direction.The stacking sequences for a large number of t phases are now known. A t 5 phase Al 5 Cu 2 Ni was reported by Bingham and Haughton (1923) and the structure of the t 3 phase Al 3 Ni 2 was elucidated by Bradley and Taylor (1937). The most extensive investigation is the work of Lu and Chang (1957) in which the Al±Cu±Ni system was explored and stacking sequences determined, for t p phases with pˆ5; 6; 7; 8; 11; 13; 15 and 17. The X-ray diOE raction analyses of van Sande et al. (1978) con®rmed the evidence for t 2 ; t 3 ; t 5 ; t 8 and t 13 …1 † but did not encounter the other members on list given by Lu and Chang.A very striking feature of the list (1) is as follows: the lengths of the repeat units of the stacking sequences are terms in the Fibonacci sequence. Motivated by this observation, Chattopadhyay et al. (1987) were led to the discovery that the actual stacking sequences of these phases are in fact rational approximants to the wellknown quasiperiodic sequence generated by the iteration rule 0 ! 1, 1 ! 10 (Elser

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One-dimensional quasi-crystals in the ternary system AlCuNi?

Cited by 21 publications

References 6 publications

Stability of mechanically alloyed vacancy ordered phase in Al₇₀Cu₁₅Ni₁₅alloy during annealing

Stability of mechanically alloyed vacancy ordered phase in Al₇₀Cu₁₅Ni₁₅alloy during annealing

Iron atomic jumps in Al–Cu–Fe quasicrystals and approximants

Stacking sequences and symmetry properties of trigonal vacancy-ordered phases (τ phases)

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One-dimensional quasi-crystals in the ternary system AlCuNi?

Cited by 21 publications

References 6 publications

Stability of mechanically alloyed vacancy ordered phase in Al70Cu15Ni15alloy during annealing

Stability of mechanically alloyed vacancy ordered phase in Al70Cu15Ni15alloy during annealing

Iron atomic jumps in Al–Cu–Fe quasicrystals and approximants

Stacking sequences and symmetry properties of trigonal vacancy-ordered phases (τ phases)

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Product

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Stability of mechanically alloyed vacancy ordered phase in Al₇₀Cu₁₅Ni₁₅alloy during annealing

Stability of mechanically alloyed vacancy ordered phase in Al₇₀Cu₁₅Ni₁₅alloy during annealing