Phase Transitions of Al&amp;ndash;Cu&amp;ndash;Fe Face-Centered Icosahedral Quasicrystals

Waseda, Atsushi; Kimura, Kaoru; Ino, Hiromitsu

doi:10.2320/matertrans1989.34.169

Cited by 5 publications

(1 citation statement)

References 28 publications

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“…a modulated transient phase). In their previous experimental work, Waseda et al (1993) found that at the composition Al 63 Cu 24 Fe 13 the i phase has its largest stability range as a function of temperature (730 < T < T m ). They calculated a hypothetical order/disorder transition temperature of 1590 K (melting temperature T m % 1100 K) based on the intensity evolution with temperature of the superstructure re¯ections (related to F-centring of the 6D Bravais lattice).…”

Section: Quasicrystalline To Crystallinementioning

confidence: 95%

Structural phase transitions from and to the quasicrystalline state

Steurer

2004

Acta Cryst Sect A

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Phase transitions from and to the quasicrystalline state show a typical signature due to some structural peculiarities. Both quasicrystals and most of their translationally periodic transformation products, the approximants, consist of the same basic structural units ('clusters'). This is the cause of low-energy interfaces between the newly forming phase and the parent phase. It is also the origin of the rather high stability of the frequently resulting orientationally twinned nanodomain structures. Owing to topological incompatibilities between quasiperiodic and periodic structures, purely displacive phase transitions are impossible. Diffusion of a significant fraction of atoms, at least on the scale of the cluster diameters, always has to take place. Locally similar icosahedral structural ordering between parent phase and nucleating phase is also responsible for the frequently occurring formation of icosahedral quasicrystals from undercooled liquid alloys or during devitrification of metallic glasses. The different types of experimentally observed phase transitions are discussed, from amorphous to quasicrystalline, quasicrystalline to ordered/disordered quasicrystalline and quasicrystalline to crystalline as a function of temperature, pressure, irradiation and high-energy ball milling, respectively.

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Section: Quasicrystalline To Crystallinementioning

confidence: 95%

Structural phase transitions from and to the quasicrystalline state

Steurer

2004

Acta Cryst Sect A

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Phase Formation and Stability

Steurer

Deloudi

2009

Crystallography of Quasicrystals

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Semiconductorlike transport in highly ordered Al-Cu-Ru quasicrystals

et al. 1994

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The electrical conductivity and Hall effect of Al-Cu-Ru and Al-Cu-Fe quasicrystals have been studied in the temperature range 4.2 -300 K. Through measurements on samples annealed at various temperatures we found that ordering of the quasicrystalline phase has a strong influence on electrical properties. The largest temperature variations of the Hall coefficient were observed in highly ordered Al-Cu-Ru samples, which also show the highest resistivities. The temperature dependence of the Hall coefficient implies that there exists a change in the carrier density. The electrical transport below 30 K is consistent with weak-localization and electronelectron-interaction theories. Conversely, at temperatures above 30 K, the observations can be consistently understood by recognizing that the increase of carrier density with increasing temperature overcomes the decrease of mobility. The characteristics of transport above 30 K are qualitatively similar to those of normal semiconductors.The discovery' of stable quasicrystals (QC's) such as Al-Cu-Fe, Al-Cu-Ru, etc. , without phason strain after annealing at high temperatures, has made it possible to investigate the properties of QC's, unobscured by defects. Now it is well known that the stable QC's have extremely high resistivities ' at low temperatures, compared with those of crystalline and amorphous solids. The better the quality of the quasicrystal, the higher the resistivity at low temperatures and the larger the negative temperature coefficient. It has been suggested that the temperature dependences of resistivity and magnetoresistivity in the low-temperature region are well described ' by weak-localization (WL) and electron-electron-interaction (EEI) theories, which were originally developed for highly disordered conductors. The origin of the high resistivity of the stable QC's has been considered to be a combination of two effects: the existence of a pseudogap in the electron density of states at the Fermi level and the localization tendency of electrons near the Fermi level. ' The former has also been considered to be the origin of the stability of QC's. Recently several authors have claimed that the electronic properties of QC's can be fully explained by the former band-structure effect alone. " ' Anomalous temperature dependences of the Hall coefficient and the thermoelectric power have also been reported. However, they are not fully explained.In this paper, we first describe the effect of ordering of QC phases on electrical properties. Then, we discuss our data on the temperature dependence of the carrier density in terms of WL and EEI theories. We have investigated the formation of the icosahedral phase with various compositions in the Al-Cu-Ru and Al-Cu-Fe systems in previous papers. ' ' Alloy ingots of more than 20 different compositions in each system were prepared by arc melting. To ensure complete mixing, each button was turned upside down and remelted four to six times. Thin ribbon samples with a thickness of -20 p, m, width of -1 mm, and length of~10 mm w...

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Phase Transitions of Al–Cu–Fe Face-Centered Icosahedral Quasicrystals

Cited by 5 publications

References 28 publications

Structural phase transitions from and to the quasicrystalline state

Structural phase transitions from and to the quasicrystalline state

Phase Formation and Stability

Semiconductorlike transport in highly ordered Al-Cu-Ru quasicrystals

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