The shear textures that develop in friction stir welds are reviewed and discussed. In all the materials examined, including face centred cubic (fcc), body centred cubic (bcc) and hexagonal close-packed (hcp) materials, friction stir welding produces a predominant shear texture with the close-packed directions aligned with the shear direction (SD) and the close-packed plane normal perpendicular ...

We study the stability of orientationally disordered crystal phases in a suspension of colloidal hard dumbbells using Monte Carlo simulations. For dumbbell bond length L/σ < 0.4 with L the separation of the two spheres of the dumbbell and σ the diameter of the spheres, we determine the difference in Helmholtz free energy of a plastic crystal with a hexagonal-close-packed (hcp) and a face-center...

We study the stability of orientationally disordered crystal phases in a suspension of colloidal hard dumbbells using Monte Carlo simulations. For dumbbell bond length L/sigma<0.4 with L the separation of the two spheres of the dumbbell and sigma the diameter of the spheres, we determine the difference in Helmholtz free energy of a plastic crystal with a hexagonal-close-packed (hcp) and a face-...

We measured the synchrotron-radiation (SR)-based Mössbauer spectra of Ni-based nanoparticles with a hexagonal structure that were synthesised by chemical reduction. To obtain Mössbauer spectra of the nanoparticles without (61)Ni enrichment, we developed a measurement system for (61)Ni SR-based Mössbauer absorption spectroscopy without X-ray windows between the (61)Ni84V16 standard energy alloy ...

A lateral dislocation in a double-layer microsphere film is very difficult to identify because the constituent domains have the same two-dimensional crystalline orientation. Orientation-sensitive optical techniques cannot resolve this issue. Here, we demonstrate that partial dark-field (pDF) optical microscopy can be very effective in identifying this type of domain boundary and dislocation of ...

Large defect-free domains of a hexagonal packed monolayer silica spheres with the size 4000 µm2 were successfully prepared by dual-speed spin coating. Experimental design and statistical analysis instead traditional ‘changing one separate factor at time’ (COST) approach employed to guide implementation experiments. With its assistance, hexagonal-close-packed (HCP) percentage was elevated 84% in...

To modify the relatively low fracture toughness of monolithic ceramics, the incorporation of long ceramic fibre within a matrix material has been extensively performed. In this case, as cracks form in the matrix material and approach the fibres, they will be deflected at the interface between the fibre and the matrix. We developed another approach toward improving the toughness of ceramics invo...

The L(h, k)-labeling is an assignment of non negative integer labels to the nodes of a graph such that ’close’ nodes have labels which differ by at least k, and ’very close’ nodes have labels which differ by at least h. The span of an L(h, k)-labeling is the difference between the largest and the smallest assigned label. We study L(h, k)-labelings of cellular, squared and hexagonal grids, seeki...

the padmakar-ivan (pi) index is a wiener-szeged-like topological index which reflectscertain structural features of organic molecules. the pi index of a graph g is the sum of alledges uv of g of the number of edges which are not equidistant from the vertices u and v. inthis paper we obtain the second and third extremals of catacondensed hexagonal systems withrespect to the pi index.

Skyrmions are topologically protected nanoscale magnetic spin entities in helical magnets. They behave like particles and tend to form hexagonal close-packed lattices, like atoms, as their stable structure. Domain boundaries in skyrmion lattices are considered to be important as they affect the dynamic properties of magnetic skyrmions. However, little is known about the fine structure of such s...