Metallic Phase with Long-Range Orientational Order and No Translational Symmetry

TL;DR: 3D periodic approximants of 3D icosahedral quasicrystalline mechanical metamaterials consisting of uniaxial chiral metarods are studied to approach nearly isotropic effective speeds of sound and isotropical acoustical activity.

TL;DR: The first observation of an approximant structure to the recently discovered two-dimensional oxide quasicrystal is reported, using scanning tunneling microscopy, low-energy electron diffraction, and surface x-ray diffraction in combination with ab initio calculations.

Abstract: An icosahedral (I) phase in coexistence with Al-phase was formed in the size fraction range up to 125 μm of atomized Al93Fe3Cr2Ti2 powder. The decomposition temperature of the I-phase is about 790 K. As per energy dispersive X-ray spectroscopy analysis, the constituent composition of the I-phase is Al84.2Fe7.0Cr6.3Ti2.5. It is found that the Al84.2Fe7.0Cr6.3Ti2.5 alloy forms a mostly single I-phase in the melt-spun state. Bulk I-alloys in a rod form were produced by extrusion of the atomized powders at 673 K and an extrusion ratio of 10. The extruded Al93Fe3Cr2Ti2 alloys have good mechanical properties, i.e., σ0.2 of 550 MPa, σUTS of 660 MPa and ep of 4.5% at room temperature and σ0.2 of 330 MPa, σUTS of 350 MPa and ep of 1.5% at 573 K. The I-based Al93Fe3Cr2Ti2 alloy is expected to be useful as a new type of high-elevated temperature strength material.

TL;DR: In this article, the authors present the resitivity and structural studies of the melt-spun Al-Mn alloys (with 10-18 at% Mn) that contain more than 50 vol% of the quasicrystalline (qX) Al//4Mn phase.

TL;DR: In this article, the stability of a moving planar liquid-solid interface during unidirectional freezing of a dilute binary alloy is theoretically investigated by calculating the time dependence of the amplitude of a sinusoidal perturbation of infinitesimal amplitude introduced into the planar shape.

TL;DR: In this article, two-and three-dimensional quasicrystals were classified by their symmetry under rotation and showed that many disallowed crystal symmetries are allowed quasici-rystal symmets.

TL;DR: In this paper, the topological and geometrical properties of coordination polyhedra are examined and rules and theorems regarding them are deduced, and general principles regarding the combination of these polyhedral groups into full structures are given for terms that facilitate the detailed discussion of this class of structures.

TL;DR: In this paper, the general principles and properties which have been deduced previously (Frank & Kasper, 1958) for the class of alloy structures are applied in an analysis and classification of representative structures.