Influence of the β-phase morphology on the corrosion of the Mg alloy AZ91

Copper oxide nanoparticles were synthesized and subsequently deposited on the surface of cotton fabrics using ultrasound irradiation. Optimization of the process resulted in a homogeneous distribution of CuO nanocrystals, 15 nm in size, on the fabric surface. The antibacterial activities of the CuO–fabric composite were tested against Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive) cultures. A significant bactericidal effect, even in a 1% coated fabric (%wt.), was demonstrated.

CuO–cotton nanocomposite: Formation, morphology, and antibacterial activity

Is quasicrystal structure analysis a never-end- ing story? Why is still not a single quasicrystal structure known with the same precision and reliability as structures of regular periodic crystals? What is the state-of-the-art of structure analysis of axial quasicrystals? The present com- prehensive review summarizes the results of almost twenty years of structure analysis of axial quasicrystals and tries to answer these questions as far as possible. More than 2000 references have been screened for the most reliable structural models of pentagonal, octagonal, decagonal and dodecagonal quasicrystals. These models, mainly based on diffraction data and/or on bulk and surface microscopic images are critically discussed together with the limits and potentialities of the respective methods employed.

https://www.degruyter.com/downloadpdf/j/zkri.2004.219.issue-7/zkri.219.7.391.35643/zkri.219.7.391.35643.xml

Twenty years of structure research on quasicrystals. Part I. Pentagonal, octagonal, decagonal and dodecagonal quasicrystals

Microstructure, fabrication and properties of quasicrystalline Al–Cu–Fe alloys: a review

Several alloy systems can be selected for high-temperature shape memory alloys (HTSMA) with stable transformation temperatures above 390 K. However, due to the lack of minimum quality standards for stability, ductility, functional behavior and reliability, no successful application have been realized so far. This paper will cover some recent developments in design of the novel Zr–Cu-based HTSMA system through the comparison with Ti–Ni–Zr and Ti–Ni–Hf alloys. Important peculiarities in shape memory behaviour of HTSMA systems mentioned above will be emphasized. Chemical homogeneity for HTSMA systems under study as well as their martensitic transformation temperatures stability and oxidation resistance will be compared also. Finally, a comparison of the weak and strong parts of Zr–Cu-based, Ti–Ni–Zr and Ti–Ni–Hf HTSMA systems will be pointed out.

High-temperature shape memory alloys: Some recent developments

The classical theory of elasticity describing three- and lower-dimensional systems is generalized to higher-dimensional spaces. The elastic properties of quasicrystals can be derived from this theory, appropriately. The practical application is given to pentagonal, octagonal, dodecagonal, and icosahedral quasicrystals. The explicit form is obtained for all elastic equations including Hooke's law, equilibrium equation, etc., in all the cases mentioned above.

Generalized elasticity theory of quasicrystals.

The first quasicrystal (QC) structure was observed in 1984. QCs possess long-range orientational and translational order while lacking the periodicity of crystals. An overview is given on some physical properties of QCs. It begins with group theory and symmetry. Then the thermodynamics of equilibrium properties and physical property tensors are discussed. Finally, the generalized elasticity theory of QCs and the elasticity theory of dislocations in QCs are presented.

https://iopscience.iop.org/article/10.1088/0034-4885/63/1/201/pdf

Symmetry groups, physical property tensors, elasticity and dislocations in quasicrystals

A one-dimensional (1D) quasicrystal (QC) is defined as a three-dimensional body which is periodic in the x - y plane and quasiperiodic in the third dimension. Knowing that the possible symmetry operations for a 1D QC are 1, 2, 3, 4, 6, m, (inversion), (horizontal twofold rotation) and (horizontal mirror reflection), 31 possible point groups of 1D QCs have been deduced. These 31 point groups are divided into ten Laue classes and six systems. Considering screw (only ) and glide (only a, b and ) operations, 80 possible space groups of 1D QCs have also been obtained. According to our generalized elasticity theory of QCs, the elastic behaviours, including independent elastic constants and invariants, for each Laue class of 1D QCs have been discussed.

Point and space groups and elastic behaviours of one-dimensional quasicrystals

Structure and substructure of martensite in a Ti36.5Ni48.5Hf15 high temperature shape memory alloy

The set of partial differential equations satisfied by the phonon and phason displacement fields u and w in quasicrystals has been solved by means of Fourier transform and eigenstrain methods, and general expressions of the elastic displacement fields induced by dislocations in quasicrystals have been given in terms of the Green function. The elastic Green tensor functions for every kind of quasicrystal are discussed in detail. Finally, as an example, the displacement fields induced by a straight dislocation line along the periodic tenfold axis of decagonal quasicrystals (three-dimensional) are calculated.

Renhui Wang

Papers

Generalized elasticity theory of quasicrystals.

Symmetry groups, physical property tensors, elasticity and dislocations in quasicrystals

Point and space groups and elastic behaviours of one-dimensional quasicrystals

Structure and substructure of martensite in a Ti36.5Ni48.5Hf15 high temperature shape memory alloy

General expressions for the elastic displacement fields induced by dislocations in quasicrystals