Quasicrystal Composites Research Articles

Effective elastic properties of one-dimensional hexagonal quasicrystal composites with spring-type imperfect interfaces

Considering the spring-type imperfect interfaces, the effective elastic properties of one-dimensional (1D) hexagonal quasicrystal (QC) are investigated systematically. The spring-type imperfect interface between QC matrix and inclusion is an ultra-thin, soft and weakly conductive interface. The Mori–Tanaka method is presented to determine the effective elastic constants of phonon, phason and phonon–phason coupling field. The numerical results are provided to show that the existence of imperfect interfaces reduces the effective elastic constants to some extent. It indicates that the interface plays an important role in the elastic properties of QC composites. Besides, the effective elastic constants are also subject to the aspect ratio and the volume fraction of inclusions.

Stress singularity of one-dimensional hexagonal piezoelectric quasicrystal composites due to thermal effect

In the framework of thermo-electro-elasticity, the present paper investigates the singular behaviors of interface corners, interface cracks, composite wedges and spaces for one-dimensional hexagonal quasicrystal. The stress function and temperature variation can be described as the exponential form with a view to stress and heat flux singularities. Based on the Stroh formalism, the analytical expressions of singular orders of stress and heat flux are easily established by simple multiplication of the crucial matrix. Numerical examples of the singular orders are given for some general cases including single, bi-material, and tri-material wedges and spaces under different boundary conditions. Numerical results show that the geometry structures, material properties, boundary conditions, and heat conduction coefficients have great influences on singularities, but thermal moduli have no effect on singularities.

Study on effective electroelastic properties of one-dimensional hexagonal piezoelectric quasicrystal containing randomly oriented inclusions

In this paper, the effective electroelastic properties of one-dimensional (1D) hexagonal piezoelectric quasicrystal containing randomly oriented inclusions are considered. The explicit expressions are obtained for the Eshelby tensors for 1D hexagonal piezoelectric quasicrystals containing rod-shaped and penny-shaped inclusions. The closed forms of the electroelastic constants are acquired for four special cases of random orientations of inclusions. Numerical results are given for the 1D hexagonal piezoelectric quasicrystal containing randomly oriented ellipsoidal inclusions. The results indicate that the effective electroelastic properties of 1D hexagonal piezoelectric quasicrystal composites are strongly affected by both the aspect ratio and the orientation of inclusions.

Eshelby Tensors for Two-Dimensional Decagonal Piezoelectric Quasicrystal Composites

The Eshelby tensor for two-dimensional (2D) piezoelectric quasicrystal composites (QCs) is considered. The explicit expressions of Eshelby tensors for 2D piezoelectric QCs are given using the Green’s function method and the interior polarization tensor method, respectively. On this basis, numerical examples of the Eshelby tensor for 2D piezoelectric QCs with ellipsoidal inclusions are discussed in detail.

Three-dimensional analysis of elliptical inclusions in two-dimensional decagonal quasicrystal

An infinite quasicrystal composites with elliptical inclusions is considered by the Green's function method. The general analytical expressions for the phonon and the phason field strain inside the inclusions are derived, respectively. Then the effective constants of the quasicrystal composites are calculated by utilizing these results. In particular, the elliptical cylindrical inclusions is analyzed in detail, the analytical expressions for the elastic constants of quasicrystal composites are given. Finally, the effects of inclusions volume fraction and shape on the effective elastic constants of quasicrystal composites are discussed.

Effective elastic properties of one-dimensional hexagonal quasicrystal composites

The explicit expression of Eshelby tensors for one-dimensional (1D) hexagonal quasicrystal composites is presented by using Green’s function method. The closed forms of Eshelby tensors in the special cases of spheroid, elliptic cylinder, ribbon-like, penny-shaped, and rod-shaped inclusions embedded in 1D hexagonal quasicrystal matrices are given. As an application of Eshelby tensors, the analytical expressions for the effective properties of the 1D hexagonal quasicrystal composites are derived based on the Mori-Tanaka method. The effects of the volume fraction of the inclusion on the elastic properties of the composite materials are discussed.

Lithium Storage Property of Graphite/AlCuFe Quasicrystal Composites

Quasicrystals have long-range quasi-periodic translational ordering and non-crystallographic rotational symmetry. Al–Cu–Fe quasicrystals have great potential for lithium storage because of their high Al content and a large number of defects in the structure. In our previous study (J. Alloys Compd. 805 (2019) 942) we showed that Al–Cu–Fe quasicrystals have good initial capacity whereas its cycle stability is poor. In the present study, graphite/AlCuFe is prepared by the mechanical alloying method. The results show that graphite/AlCuFe quasicrystal composites are successfully synthesized by planetary ball milling at 550 rpm for 80 h. The quasicrystal particle size decreases and the amorphous graphite forms onion-like carbon (OLC) when the two phases mix evenly. OLC forms on the surface of the Al–Cu–Fe quasicrystalline powder. Charge and discharge tests show that graphite/AlCuFe quasicrystal composites have high-stability capacity of 480 mAh/g after 20 cycles, which is larger than the sum of capacities of graphite and Al–Cu–Fe quasicrystals.

EVOLUTION OF THE PHASES OF QUASICRYSTALLINE ALLOYS ICOSAHEDRAL/ DECAGONAL Al62.2Cu25.3 Fe12.5/Al65Ni15Co20 AND OXIDATIVE BEHAVIOR

In this paper, we present an approach and investigation on the evolution of the icosahedral and decagonal phases of quasicrystalline alloys Al62.2Cu25.3Fe12.5 E Al65Ni15Co20, the oxidation behavior in them. The quantification of the quasicrystalline and crystalline phases present in the quasicrystals provides important information in the mass transport by diffusion, as well as the phase transformations that occurred. For this purpose, X-ray diffraction (XRD) and Rietveld Method Quantification, Scanning Electron Microscopy (SEM) / Dispersive Energy Spectroscopy (EDS), Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis). The results showed structural aspects of the two compositions of quasicrystals, these were elaborated and obtained in an arc induction furnace. The oxidation of the alloy Al62.2Cu25.3Fe12.5 showed intermetallic phases with associations of the elements of the alloy and above 735 °C was observed that the crystalline phase is stable in the icosahedral phase. The quasicrystals Al65Ni15Co20, with the interaction of oxygen, happens in the surface of symmetry 10 times plane perpendicular vector. The formation of a thin film of the aluminum oxide with a well ordered hexagonal shape structure, with a domain opposite the decagonal phase with lateral size at about 35 A.

Effective electroelastic constants for three-phase confocal elliptical cylinder model in piezoelectric quasicrystal composites

A three-phase confocal elliptical cylinder model is proposed to analyze micromechanics of one-dimensional hexagonal piezoelectric quasicrystal (PQC) composites. Exact solutions of the phonon, phason, and electric fields are obtained by using the conformal mapping combined with the Laurent expansion technique when the model is subject to far-field anti-plane mechanical and in-plane electric loadings. The effective electroelastic constants of several different composites made up of PQC, quasicrystal (QC), and piezoelectric (PE) materials are predicted by the generalized self-consistent method. Numerical examples are conducted to show the effects of the volume fraction and the cross-sectional shape of inclusion (or fiber) on the effective electroelastic constants of these composites. Compared with other micromechanical methods, the generalized selfconsistent and Mori-Tanaka methods can predict the effective electroelastic constants of the composites consistently.

OXIDATION INFLUENCE ON THE QUASICRYSTALLINE PHASES OF ALLOYS Al62.5Cu25Fe12.5 AND Al65Ni15Co20

In this article we will cover a study of the formation of icosahedral and decagonal phases two quasicrystals Al 62.5 Cu 25 Fe 12.5 and Al 65 Ni 15 Co 20 oxidation of influence in this alloy. For this purpose research used the diffraction of X-ray, scanning electron microscopy/energy dispersive spectroscopy, differential scanning calorimetry and thermogravimetric analysis. The results displayed found aspects of morphological structural as well as the surface of the two compositions of quasicrystals, these were prepared and obtained in electric arc furnaces and induction and arc. Oxidation of Al 62.5 Cu 25 Fe 12.5 alloy, intermetallic phases presented with combinations of alloying elements and above 675°C it was observed that the crystalline phase is stable. In icosahedral phase oxidation of aluminum forms a dense layer on the passivating outer most surface of the quasicrystal which causes depletion in both copper and iron. In Al 65 Ni 15 Co 20 nominal composition of oxygen interaction occurs on the surface of symmetry 10 times plane perpendicular vector .The formation of a thin film of aluminum oxide having well-ordered hexagonal structure and with the opposition area decagonal phase with the lateral size of approximately 35A .

Al62Cu25Fe12 and Quasicrystalline Phases and Their Influence on Oxidation

In this article, we will cover a study of the formation of icosahedral and decagonal phases two quasicrystals Al 62 Cu 25 Fe 12 and Al 65 Ni 15 Co 20 oxidation of influence in this alloy. For this purpose, research used the diffraction of X-ray, scanning electron microscopy/energy dispersive spectroscopy, differential scanning calorimetry and thermogravimetric analysis. The results displayed found aspects of morphological structural as well as the surface of the two compositions of quasicrystals, these were prepared and obtained in electric arc furnaces and induction and arc. Oxidation of Al 62 Cu 25 Fe 12 alloy, intermetallic phases presented with combinations of alloying elements and above 675 °C it was observed that the crystalline phase is stable. In icosahedral phase oxidation of aluminum forms a dense layer on the passivating outer most surface of the quasicrystal which causes depletion in both copper and iron. In Al 65 Ni 15 Co 20 nominal composition of oxygen interaction occurs on the surface of symmetry 10 times plane perpendicular vector. The formation of a thin film of aluminum oxide having well-ordered hexagonal structure and with the opposition area decagonal phase with the lateral size of approximately 35A. DOI: http://dx.doi.org/10.17807/orbital.v9i1.872

Three-Phase Cylinder Model of One-Dimensional Hexagonal Piezoelectric Quasi-Crystal Composites

A three-phase cylinder model (inclusion/matrix/composite) is proposed and analyzed for one-dimensional (1D) piezoelectric quasi-crystal composites. The exact closed-form solutions of the stresses of the phonon and phason fields and the electric field are derived under far-field antiplane mechanical and in-plane electric loadings via the Laurent expansion technique. Numerical results show that the thickness and material properties of the interphase layer can significantly affect the induced fields in the inclusion and interphase layer. Furthermore, the generalized self-consistent method is applied to predict analytically the effective moduli of the piezoelectric quasi-crystal composites. It is observed from the numerical examples that the effective moduli of piezoelectric quasi-crystal composites are very sensitive to the fiber volume fraction as well as to the individual material properties of the fiber and matrix. By comparing QC/PE with QC1/QC2, PE/QC, and PZT-7/epoxy, we found that using QC as fiber could, in general, enhance the effective properties, a conclusion which is in agreement with the recent experimental results.

Effect of a quasicrystalline filler on the tribological properties of a composite based on ultrahigh-molecular-weight polyethylene

We prepare composites in which ultrahigh-molecular-weight polyethylene (UHMWPE) is used as a matrix and quasicrystalline Al–Cu–Fe powder is used as a filler with concentrations of 1, 10, 30, and 50 vol %. The mechanical and tribological properties of the samples are measured, and electron microscopic studies of fractured regions are performed. It is shown that with increasing concentrations of the filler, the nature of fracturing of the samples changes. The minimum value of the friction coefficient is 0.07. It is assumed that the limiting factor in improving the tribological properties of UHMWPE–quasicrystal composites is the chipping of filler particles from the polymer matrix.

Structure and properties of mechanically alloyed composite materials Al/Al-Cu-Fe quasicrystal

The structure and properties of metal-matrix Al/Al-Cu-Fe-quasicrystal composites produced by compacting mechanically alloyed powders have been studied. An increase in the time of mechanical alloying was found to lead to an increase in the microhardness. Compression tests showed that the failure of samples occurred via the intense formation of cracks along the direction parallel to the applied stresses; the ultimate strength increases with increasing time of mechanical alloying. As the compacting temperature increases, the ultimate strength remains unchanged to temperatures of 300–400°C; at higher temperatures, a marked increase in the ultimate compression strength is observed. An increase in the compacting temperature leads to an improvement of frictional characteristic of samples.