The recognition of metal-organic frameworks (MOFs) with the 2025 Nobel Prize in Chemistry underscores the critical importance of their porous and tunable architectures for applications like atmospheric water harvesting, carbon dioxide capture, and toxic gas storage. Understanding the mechanical properties of zeolites, open-framework aluminophosphates (AlPOs), and MOFs porous materials is essential for predicting their practical applications and synthesizability. By applying Alan L. Mackay's concept of "generalized crystallography," we extend principles from these microporous crystals to the design of 3D-printed macroporous metamaterials and the derivation of universal, multiscale patterns. We validate the relevance of this method by detecting correlations between structural motifs and mechanical data for metamaterials consistent with results from density functional theory (DFT) calculations for crystals. The crystal chemical analysis involved simplifying crystal structures into nets by constructing Voronoi-Dirichlet polyhedra (VDP) using TOPOS or TopCryst in a fully automated mode. A strong correlation between mechanical properties and the deviation of average, maximum, and minimum bond angles from the regular angles of nets based polyhedral was found. Pearson correlation analysis also showed that greater distances between nodes in zeolites maximize their mechanical properties. This means that SiO4 tetrahedra should join as "straightforwardly" as possible, without any bends that would reduce mechanical strength. For 3D-printed AlPOs, we observed a strong negative Pearson correlation between mechanical properties and the number of nodes and bonds, whereas for MOFs, the correlation is positive. This suggests the existence of an optimal value for these parameters to maximize mechanical properties at a given porosity. The discovered regularities provide the fast screening of both the most durable porous materials and 3D printed metamaterials.
Owing to inter-phase orientation relationship, EBSD analysis of martensitic or bainitic steel enables reconstruction of prior grains. Thus, assessment of the treatment conditions remains possible even if the chemical etching cannot properly reveal the parent structure. However, such an approach is hardly applicable to the industrial modes of multi-pass rolling. Unlike a single thickness reduction, small strains per pass followed by a kind of annealing in inter-pass pauses cause specific mechanisms of austenite recrystallization so that the latter becomes difficult to be assessed in morphological terms. At the same time, the textural analysis enables estimation of the parent state using whether the texture of reconstructed austenite or the measured transformation texture. When tested on low carbon bainitic steel, both methods lead to close estimates of the parent texture and thus support each other.
With increasing operating speeds and contact loads of structural elements, it is necessary to increase the operational life of friction units, which can be ensured by improving the physical and mechanical properties of the contact surfaces. The paper presents the results of investigations of the properties of coatings formed from nanostructured composite powders of the Ti/TiO 2 system by microplasma spraying. Experimental data on the synthesis of nanostructured powders based on a titanium matrix reinforced with titanium dioxide nanopowders are presented. PTOM-1 titanium powder with a fraction of less than 90 μm and nanoscale titanium dioxide powder with a fraction of 80 – 200 nm were used as starting materials. Mixtures of starting materials with variable TiO 2 content were subjected to preliminary homogenization and subsequent mechanosynthesis. When studying the morphology of the synthesized powders, it was revealed that the shape of the particles is inherited from the matrix powder, and with an increase in the content of the reinforcing component, the surface of the composite powder is more densely reinforced with particles of TiO 2 nanopowder. The determination of the fractional composition showed that the maximum volume fraction of particles (62. 5 % wt.) it corresponds to a size of 10 – 40 μm. Scanning electron microscopy of transverse microspheres revealed that there are no through pores in all coatings. With an increase in the titanium dioxide content to 24 %, porosity increases significantly, and there is also a detachment of the coating material from the substrate. A study of the microhardness of the sprayed coatings showed that the hardest coating (on average 985 HV ) was obtained by spraying a synthesized powder with a titanium dioxide content of 16 % by weight. The results obtained can be used to extend the life of, for example, titanium alloy ball valves used in autoclaves for the mining industry.
The mapping of crystal curvature by the electron backscatter diffraction (EBSD) is conventionally used to image agglomerations of the Burgers vector (e. g., low-angle boundaries) in terms of geometrically necessary dislocations (GND). However, the concurrent curvature constituent due to statistically stored dislocations (SSD) still is not separated that remains a challenging problem because the material properties strongly depend on the proportion between GND and SSD densities. To get over this trouble, the present work analyzes the dependence of measured disorientations on the scanning step and thus determines its upper bound that mostly excludes the contribution of GND as manifested by strongly increased variations of measurement results. This way, a slope of the analyzed dependence within an admitted range of appropriately small steps enables determination of SSD density in terms of regular EBSD data. The latter avoids limitations of transmission electron microscopy (TEM) and X-ray diffraction (XRD) which usually apply to dissimilar scales and provide rather different estimates. For a case study, this approach is tested on lath-like and granular types of bainite in low carbon steel. Varying in the density proportion between coexisting bulk SSD and interfacial GND, such structures prove to be very suitable to verify performance of the proposed method.
The paper presents the results of the microstructure study of spherulitic islands in thin films of lead zirconate titanate, characterized by either a non-uniform radial rotation of the crystal lattice (radiant microstructure) or a uniform rotation, which allows one to detect Kikuchi lines of electron channeling. Thin lead zirconate titanate films were obtained by a two-stage method of radio-frequency magnetron sputtering of a ceramic target: deposition onto a << cold >> platinized silicon and glassceram substrates, followed by high-temperature annealing to obtain islands of the perovskite phase surrounded by a matrix of the low-temperature pyrochlore phase. To study the cross section, a lamella was prepared, the study of the microstructure of which showed that the rotation of the crystal lattice in the perovskite spherulite occurs uniformly throughout the entire thickness, and it is not a manifestation of some near-surface effects. It was found that the rate of rotation of the crystal lattice in spherulites with a radial-radiant structure is approximately two times less than in spherulites with a radially uniform rotation; a model of translational rotation of the crystal lattice with the formation of dislocations and partial relaxation of mechanical stresses is proposed; it is assumed that the lattice rotation velocity is limited by the elasticity limit of the thin film. It is assumed that the Kikuchi image in spherulitic islands consisting of crystalline grains is determined by both the identical growth texture and the orientational correlation of the grains in the plane of the film; an analysis and interpretation of Kikuchi electron channeling lines has been carried out, which makes it possible to determine the orientation of the crystal lattice planes and growth axes in thin films. Keywords: thin films of lead zirconate titanate, spherulites, radially-radiant microstructure, electron Kikuchi channeling.
