In this paper, the effect of sputtering on the surface composition of an Al-Pd-Mn QUASICRYSTAL has been studied using 2KeV He+. It was found that the surface concentration of Al decreases smoothly to a steady state under bombardment and the Mn and Pd concentrations increase. The surface enriched in Mn was annealed and it was found that there was no detectable surface Mn at temperatures higher than 575K. Finally, the variation of the ratio of the AlPdsurface concentration with changes in temperature was measured.

Introduction: In the present study, the Al72Cr17Fe11 QUASICRYSTAL nano-powder was synthesized through mechanical alloying. Phase investigation revealed the formation of decagonal QUASICRYSTAL structure on a nanometer scale. Methods: After that, the aluminum matrix composites reinforced by 3 wt. % of produced QUASICRYSTAL powder were fabricated by using the accumulative roll bonding process. Microstructural and mechanical properties were evaluated using scanning electron microscopy and microhardness and tensile tests, respectively. Findings: Microstructural studies showed that there was an improvement in the distribution of the QUASICRYSTALline reinforcement phase in the aluminum metal matrix composite as well as an improvement in the bonding between the layers by increasing the cycles of the accumulative roll bonding process. Investigation of microhardness changes showed an increase in hardness value by adding a reinforcing phase in comparison to pure aluminum in the range of 74. 5 to 105. 8 Vickers after 8 cycles. Stress-strain curves of composite specimens showed that the tensile strength of composite specimens and their elongation increase continuously with increasing cycles of the accumulative roll bonding process. Tensile strength increased between 165 to 250 MPa with increasing rolling cycles from 2 to 8. The maximum toughness (30. 2 (energy/volume (MPa)) was obtained after 8 cycles.

Design of some crystal and QUASICRYSTAL networks, based on rhombellane tiling, is presented. [1, 1, 1]Propellane, is a synthesized organic molecule; its hydrogenated form, the bicyclo[1. 1. 1]pentane, may be represented by the complete bipartite graph K2, 3 which is the smallest rhombellane. Topology of translational and radial structures involving rhombellanes is described in terms of vertex symbol, connectivity sequence, ring sequence and map operations relating structures to their seeds. It is shown, by alternating sum of ranked substructures, that radial structures represent complex constructions of higher rank. Basic properties of rhombellanes, coloring included, are outlined.

QUASICRYSTALs compounds have ordered structure, which is comparable with crystalline materials, but and are aperiodic. The formation of QUASICRYSTALline structures was reported in Al-base, Ti-base, Zr-base and Mg-base alloys. One of the classes of these advanced materials is Al-Cu-Ni systems which have vacancy ordered phases (VOP) knowing as one-dimensional QUASICRYSTALs. Since there have been limited reports on the synthesis of the Al-Cu-Ni intermetallic by mechanical alloying (MA), the production of Al70Cu20Ni10 compound by MA and subsequent heat treatment was canied out in this work. Afterward, the stmctural properties of the prepared samples were conducted by x-ray diffraction (XRD) and the corrosion behavior of the compounds was studied by linear polarization test. It was found that by increasing the annealing temperatures, the amount of one-dimensional QUASICRYSTALs (t3) increases and in contrast, the Al2Cu (q) crystalline intermetallic compound quantity decreases, respectively. Moreover, the corrosion test results were revealed that the corrosion resistance behavior is improved by increasing the fraction of t3 phases.

Using a tight-binding model and transfer-matrix technique, as well as Lanczos algorithm, we numerically investigate the nature of the electronic states and electron transmission in site, bond and mixing Fibonacci model chains. We rely on the Landauer formalism as the basis for studying the conduction properties of these systems. Calculating the Lyapunov exponent, we also study the localization properties of electronic eigenstates in the Fibonacci chains.. The focus is on the significance of the relationship between the transmission spectra and the nature of the electronic states. Our results show that, in contrast to Anderson's localization theorem, in the Fibonacci chains the electronic states are non-localized and the transparent states occurr near the Fermi level.

Rhombellanes are mathematical structures existing in various environments, in crystal or QUASICRYSTAL networks, or even in their homeomorphs, further possible becoming real molecules. Rhombellanes originate in the K2. 3 complete bipartite graph, a tile found in the linear polymeric staffanes. In close analogy, a rod-like polymer derived from hexahydroxy-cyclohexane was imagined. Further, the idea of linear polymer synthesized from dehydroadamantane was extended in the design of a threedimensional crystal network, named dia(s), of which tile is a hyper-adamantane (an adamantane of which vertices are just adamantanes). It was suggested that this network could be synthesized starting from the real molecule tetrabromo-adamantane, by dehydrogenation and polymerization. The crystal structures herein proposed were characterized by connectivity and ring surrounding sequences and also by the omega polynomial.

Rhombellanes are mathematical structures existing in various environments, in crystal or QUASICRYSTAL networks, or even in their homeomorphs, further possible becoming real molecules. Rhombellanes originate in the K2. 3 complete bipartite graph, a tile found in the linear polymeric staffanes. In close analogy, a rod-like polymer derived from hexahydroxy-cyclohexane, HHCH, was imagined. Further, the idea of linear polymer synthesized from dehydro-adamantane, DHAda, was extended in the design of a threedimensional crystal network, called here Ada-Ada, of which tile is a hyper-adamantane (an adamantane of which vertices are just adamantanes). It was suggested that Ada-Ada would be synthesized starting from the real molecule tetrabromo-adamantane, by dehydrogenation and polymerization. The crystal structures herein proposed were characterized by connectivity and ring sequences and also by the Omega polynomial.

In this study, Al-based composites reinforced with Al59Cu25.5Fe12.5B3 QUASICRYSTAL (QC) were prepared by spark plasma sintering (SPS) method. Microstructural and mechanical properties were examined. It is observed that with addition of quasi-crystalline reinforcement the intensity of the quasi-crystalline peak has increased. Also, it is observed that by performing spark plasma sintering, the quasi-crystalline particles maintain their stability. Due to low temperature of the process and the short time of spark plasma sintering, the occurrence of destructive phases within the quasi-crystal has been prevented. based on field emission scanning electron microscopy (FESEM) images, the distribution of quasi-crystalline particles at the sample level has increased. In addition, the mechanical properties are improved by increasing the quasi-crystalline particles. Therefore, the sample with 15 vol.% of quasi-crystal has better results than other samples in improving microstructural and mechanical properties and it can be considered as an optimal sample with suitable practical properties.

In this article, the transient dynamic analysis of decagonal QUASICRYSTAL (QC) is carried out using the meshless generalized finite difference (GFD) method. The transient behaviors of phonon and phason displacements in these types of QCs, when they are subjected to mechanical shock loading are studied. Also, the meshless GFD method is developed to solve the dynamic problems of QCs, considering coupling between phonon and phason displacements. The governing equations of the problem are obtained in the coupled system of PDEs by applying the coupling coefficient in the governing equations to simulate the interaction between phonon and phason displacements. A 2D rectangular domain made from decagonal (Al-Ni-Co) QCs is assumed for the problem to show the transient behaviors of phonon and phason displacements, when one side of 2D domain is excited by phonon displacement shock loading. Based on the coupling between phonon and phason displacements, any disturbance in phonon field causes some variations in phason field. To study the dynamic behaviors of phonon and phason fields, the coupled governing equations are transferred to Laplace domain. After analysis the problem by GFD method, the obtained results in Laplace domain are transferred to time domain using the Laplace inversion technique. The interactions between phonon and phason fields are studied in details. Also, the effects of coupling parameter and the phason friction coefficient on the dynamic and transient behaviors of phonon and phason displacement fields are obtained and discussed in details.