Search Results (215)

This study proposes a coupled constitutive model that captures the anisotropic failure characteristics and damage evolution of nickel-based single-crystal (SX) superalloys under various temperature conditions. The model accounts for both creep rate and material damage evolution, enabling accurate prediction of the typical three-stage creep curves, macroscopic fracture morphologies, and microstructural features under uniaxial tensile creep for specimens with different crystallographic orientations. Creep behavior of SX superalloys was simulated under multiple orientations and various temperature-stress conditions using the proposed model. The resulting creep curves aligned well with experimental observations, thereby validating the model’s feasibility and accuracy. Furthermore, a finite element model of cylindrical specimens was established, and simulations of the macroscopic fracture morphology were performed using a user-defined material subroutine. By integrating the rafting theory governed by interfacial energy density, the model successfully predicts the rafting morphology of the microstructure at the fracture surface for different crystallographic orientations. The proposed model maintains low programming complexity and computational cost while effectively predicting the creep life and deformation behavior of anisotropic materials. The model accurately captures the three-stage creep deformation behavior of SX specimens and provides reliable predictions of stress fields and microstructural changes at critical cross-sections. The model demonstrates high accuracy in life prediction, with all predicted results falling within a ±1.5× error band and an average error of 14.6%. Full article

A new polymorph of N-(1,3-thiazol-2-yl)benzamide crystallises in the monoclinic space group Pc with four crystallographically independent molecules (Z′ = 4) in the asymmetric unit. Where the previously reported polymorphs exhibit two distinct hydrogen-bonded dimer geometries exclusively, the asymmetric unit of the new polymorph comprises both. Approximate symmetry was observed to relate the molecules of these dimers. These approximate symmetry elements combine to form a structure with distorted P2₁/c space group symmetry, rationalising the unexpectedly high number of crystallographically independent molecules. Full article

In this study, 3-chlorothiophene-2-carboxylic acid (HL) was used as a main ligand to successfully synthesize four novel complexes: [Cu(L)₂(Py)₂(OH₂)₂] (1), [Co(L)₂(Py)₂(OH₂)₂] (2) (Py = pyridine), [{Ni(L)₂(OH₂)₄}₂{Ni(L)(OH₂)₅}]L•5H₂O (3), and [{Co(L)₂(OH₂)₄}₂{Co(L)(OH₂)₅}]L•5H₂O (4). All four compounds were identified by elemental analysis and ESI mass spectrometry, and subsequently characterized by IR spectroscopy, UV-visible diffuse reflectance spectroscopy, electron paramagnetic resonance spectroscopy, thermogravimetric analysis, single-crystal X-ray crystallography, and cyclic voltammetry. X-ray analyses revealed that complexes 1 and 2 exhibit a centrosymmetric pseudo-octahedral coordination geometry; the copper (II) and cobalt (II) metal ions, respectively, are located at the crystallographic center of inversion. The coordination sphere of the copper (II) complex is axially elongated in accordance with the Jahn–Teller effect. Intriguingly, for charge neutrality, compounds 3 and 4 crystallized as three independent mononuclear octahedrally coordinated metal centers, which are two $\left[\mathrm{M}{\mathrm{L}}_2{\left({\mathrm{O}\mathrm{H}}_2\right)}_4\right]$ complex molecules and one ${\left[\mathrm{M}\mathrm{L}{\left({\mathrm{O}\mathrm{H}}_2\right)}_5\right]}^{+}$ complex cation (M = ${\mathrm{N}\mathrm{i}}^{\mathrm{I}\mathrm{I}}$ and ${\mathrm{C}\mathrm{o}}^{\mathrm{I}\mathrm{I}}$, respectively), with the ligand anion ${\mathrm{L}}^{-}$ serving as the counter ion. The anticancer activities of these complexes were systematically assessed on human leukemia K562 cells, lung cancer A549 cells, liver cancer HepG2 cells, breast cancer MDA-MB-231 cells, and colon cancer SW480 cells. Among them, complex 4 shows significant inhibitory effects on leukemia K562 cells and colon cancer SW480 cells. Full article

Aluminum and its alloy magnetron sputtering targets, owing to their superior electrical/thermal conductivity and robust substrate adhesion, serve as critical materials in advanced electronics and information technologies. It is known that the microstructure of the target, including grain uniformity and crystallographic texture, directly affects the sputtering performance and the quality of the deposited thin film. Despite extensive research efforts, the review paper focused on the microstructure of aluminum target materials is still absent. In that context, the recent progress on the Al alloy target is reviewed, focusing on grain refinement and texture control strategies. The roles of alloying elements, such as Si, Cu, and rare-earth Sc and Nd, are described first. The two conventional manufacturing techniques of fabricating Al targets, including melting and powder metallurgy, are introduced. Then, studies on grain refinement by thermomechanical processing routes (hot/cold rolling, annealing and forging) are summarized. Lastly, texture engineering through deformation and heat treatment protocols (unidirectional/multidirectional rolling, deformation thickness, and composite deformation modes) is reviewed. By establishing the relationship between thermomechanical processing and microstructure, this review provides insights for designing high-performance aluminum targets tailored to next-generation advanced thin-film applications. Full article

The treatment of trans-dihydroxo[5,10,15,20-tetrakis(3-pyridyl)porphyrinato]Sn(IV) or [Sn(OH)₂(TPyP)] with 1% nitric acid in a mixture of water and acetone resulted in the formation of an ionic complex 1 [Sn(OH)₂(TPy^HP)](NO₃)₄. Complex 1 was fully characterized by ¹H NMR spectroscopy, elemental analysis, UV-vis spectroscopy, powder X-ray diffraction, fluorescence spectroscopy, FT-IR spectroscopy, and single-crystal X-ray crystallography. X-ray crystallographic analysis confirmed that each peripheral pyridyl N atom is protonated to form tetra-cationic species {Sn(OH)₂(TPy^HP)}⁴⁺ stabilized by four NO₃⁻ counter anions. Intermolecular hydrogen bonding interaction between axial hydroxo ligands leads to the formation of a 1D porphyrin array. Nitrate anions also involve hydrogen bonding interactions with axial hydroxo ligands and the peripheral pyridinium groups. Full article

The main constituent of the planetary lithosphere is the dominant silicate mineral, olivine α-(Mg,Fe)₂SiO₄, which, along with associated minerals and the olivine-hosted inclusions, records the physical–chemical conditions during the crystal growth and transport to the planetary surface. However, there is a lack of physical–chemical information regarding the kinetic factors that regulate crystal growth during melt–rock, fluid–rock, and magma–rock interactions. Here, we conducted an experimental reaction between hydrated peridotite rock and basaltic melt and coupled this with a structural and elemental analysis of the quenched products by high-resolution transmission electron microscopy. The quenched products revealed crystallographically oriented oxide nanocrystals of ilmenite (Fe,Mg)(Ti,Si)O₃ that grew over the newly formed olivine in the boundary layer melt of the reaction zone. We established that the growth mechanism is epitaxial and is common to both experimental and natural systems. The kinetic model developed for shallow (<1 GPa) crystal growth requires open system conditions and the presence of melt or fluid. It implies that the current geodynamic models that consider natural ilmenite–olivine assemblage as a proxy for deep to ultra-deep (>>1 GPa) conditions should be revised. The resulting kinetic model has a wide range of geological implications—from disequilibrium mineral growth and olivine-hosted inclusion production to mantle metasomatism—and helps to clarify how geological reactions proceed at depth. Full article

The interface morphology plays an important role in the mechanical properties of laminated metal composites (LMCs). In this study, binary LMCs with different crystallographic characteristics, namely Fe/Al (BCC/FCC), Ni/Al (FCC/FCC), and Mg/Al (HCP/FCC), were fabricated through the hierarchical roll-bonding process. The influence of interface morphology on the mechanical properties of the binary LMCs was investigated systematically. The results show that the strength–hardness coefficient (R) decreases with increasing interface morphology factor (α) for the LMCs, indicating that the strengthening effect of LMCs decreases with increased curvature of the interface. The experimental results reveal that α increases with the increase in rolling deformation (thickness reduction) for the LMCs, which is consistent with the finite element simulation results. The dependence of mechanical properties on interface morphology is mainly related to the microstructural inhomogeneity caused by localized deformation in the harder layer, including the formation of shear bands and variations in grain morphology, size, and orientation, which can lead to stress concentration in the necking zone. Full article

The purpose of this study is to investigate the effects of process parameters on the microstructure and mechanical properties of the Hastelloy X (HX) alloy using a laser powder bed fusion (L-PBF) process. A combined experimental and numerical approach was used to evaluate the influence of the energy density distribution and temperature evolution on the microstructure, defects, and mechanical properties. After the specimens were built on SUS304 substrate by the L-PBF, the microstructure and defects in the specimens were analyzed by SEM and EBSD analysis methods, and then the hardness and the tensile tests were performed. The cooling rate under different laser conditions was obtained by the finite element method (FEM). The results show that a low volume energy density (VED) was applied to the unmelted powder particles, and a high energy density resulted in spherical defects. In addition, the microstructures were found to coarsen with increasing the energy density along with a tendency to strengthen the (001) texture orientation in both x–y and x–z planes. Compared to the parts with the thermal history from numerical results, the low cooling rate with high energy density had larger crystal grains elongated along the building direction, coarser sub-grains, resulting in a reduction in microhardness and yield strength together with an increase in elongation for the L-PBF HX alloy. The presented results provide new insights into the effects of parameters and the cooling rates. It can play an important role in optimizing the L-PBF processing parameters, identifying the cause of defects, and controlling the cooling rates for the crystallographic texture in such a way as to guide the development of better metrics for designing processing parameters with the desired mechanical properties. Full article

The influence of intrinsic impurities on the formation of band-like inhomogeneities in ZGP single crystals containing two highly volatile elements has been analyzed. It has been shown that the formation of growth bands occurs due to the accumulation of binary phosphides at the crystallization front and is accompanied by the formation of pores in the near-wall region of the ingot. A connection between near-wall pore formation and the presence of growth bands in ZGP has been established. X-ray spectrometry revealed differences in the chemical compositions of “light” and “dark” growth striations, with significant deviations from stoichiometry in these regions. The dark bands exhibited a higher phosphorus content compared to the light bands and showed an increased germanium content in the light bands. Differences in the orientation of crystallographic axes were observed between the light and dark regions. It has been shown that samples containing inclusions of band-like inhomogeneity significantly distort the profile of the radiation passing through and generated in the crystal and lead to pronounced astigmatism. However, in contrast to the extremely negative influence of banded inhomogeneity on the optical properties of single crystals, the influence of growth striations on the radiation resistance of crystals is minimal. Full article

This article evaluates the possibility of replacing creep-resistant magnesium Mg-Zn-RE-Zr alloys (EZ33) with Mg-Al-Ca-Sr alloys. (1) Background: Mg alloys with RE metals show excellent properties. Due to their high cost, new, more economical Mg alloys are being developed. Replacing RE metals with cheaper elements such as Al and Ca allows us to obtain high mechanical properties at elevated temperatures due to the tendency to form stable intermetallic phases. (2) Methods: Microstructure analysis (LM, SEM, TEM, and XRD) was performed and mechanical properties were tested at ambient and elevated temperatures. (3) Results: Increasing the Ca content and decreasing the Al content leads to the formation of a continuous skeleton of high-melting and brittle Ca-rich Laves phases and Sr-rich intermetallic phases and the formation of plate-like precipitates of the C15 phase inside the α-Mg solid solution. The crystallographic orientation of plate-like precipitates contributes to the blocking of dislocations in slip systems activated at elevated temperatures. Increasing the Ca and Sr content allows for the regulation of the Al concentration in the α-Mg, providing solution strengthening and stability of the α-Mg solid solution. These factors contribute to a significant improvement in creep resistance of Mg-Al-Ca-Sr alloys. (4) Conclusions: The strength properties and elongation at ambient temperature of the Mg alloys with Ca and Sr addition are comparable to those of the EZ33 alloy, and due to the presence of lighter alloying elements, a better specific strength is achieved. Ca-rich Mg-Al-Ca-Sr alloys exhibit better creep resistance at temperatures of up to 200 °C compared to the EZ33 alloy. Full article

A set of samples from the Monte Castelo kaolin deposits (Burela, NW Spain), corresponding to igneous acidic rocks affected by chemical weathering with variable intensity have been investigated in order to establish the mineralogical and chemical changes with weathering, and the micro- and nano-scale textures developed. For the study, XRD, FESEM, HRTEM and chemical analyses have been used. The more intense the weathering, the more the dissolution of aluminosilicates (albite, K feldspars and K micas) and the crystallization of kaolinite is favored. Kaolinite grows, forming booklets and generating a fine-grained matrix and, along the cleavages of muscovite, forming mica–kaolinite intergrowths. Bidimensional crystallographic continuity between mica and kaolinite has been observed and no intermediate phases have been identified as a consequence of the high W/R ratio. Kaolin mainly contains kaolinite with high crystallinity; however, when there are quartz impurities, they interfere with the ‘optimal’ reflections for the calculation of the Hinckley index. In this case, the use of the AGFI index almost eliminates the effect that the relative intensities of the quartz and feldspar impurities may have on those of kaolinite. With weathering, there is a progressive decrease in the contents of most chemical elements, except Al, TiO₂, HREEs, Ta, Hf, Th, U, V, Cr, S, Zr, Mo and Sn. Full article

Hydrogen can be easily captured by the rare-earth (RE) elements in hydrogen-rich environments, which significantly affect the phase compositions and mechanical performance of Mg-RE based alloys. However, the morphology of RE hydrides and their orientation relationships (ORs) with the Mg matrix have not been well explained. Here, a stable face-centered cubic (FCC) ${\left(\mathrm{G}\mathrm{d},\mathrm{Y}\right)\mathrm{H}}_2$ hydride was introduced and uniformly distributed in a Mg-15Gd-2.5Y-1Al alloy after hydrogenation treatment at 500 °C and 2 MPa for 40 h. The plate-like ${\left(\mathrm{G}\mathrm{d},\mathrm{Y}\right)\mathrm{H}}_2$ hydride with six variants was identified to exhibit an OR with the magnesium (Mg) matrix, which is ${\left[0001\right]}_{\mathrm{M}\mathrm{g}}$//${\left[001\right]}_{{\left(\mathrm{G}\mathrm{d},\mathrm{Y}\right)\mathrm{H}}_2}$, ${\left(10\overline{1}0\right)}_{\mathrm{M}\mathrm{g}}{10.5}^{\circ }$ from ${\left(002\right)}_{{\left(\mathrm{G}\mathrm{d},\mathrm{Y}\right)\mathrm{H}}_2}$, ${\left(1\overline{2}10\right)}_{\mathrm{M}\mathrm{g}}{10.5}^{\circ }$ from ${\left(020\right)}_{{\left(\mathrm{G}\mathrm{d},\mathrm{Y}\right)\mathrm{H}}_2}$. Further crystallographic matching calculations based on the edge-to-edge matching model suggest that such an OR is energetically favorable and provides the actual interface between the RE hydrides and the Mg matrix during precipitation. Our findings offer new insights into the microstructural regulation of Mg alloys in hydrogenation environments. Full article

We present structural, morphological, optical and photocatalytic properties of multiferroic Bi_0.98Ba_0.02FeO₃ (BBFO2) perovskite thin films prepared by a combined sol–gel and spin-coating method. X-ray diffraction (XRD) analysis revealed that all the perovskite films consisted of the stable polycrystalline rhombohedral phase structure (space group R3c) with a tolerance factor of 0.892. By using Rietveld refinement of diffractogram XRD data, crystallographic parameters, such as bond angle, bond length, atom position, unit cell parameters, and electron density measurements were computed. Scanning electron microscopy (SEM) allowed us to assess the homogeneous and smooth surface morphology of the films with a small degree of porosity, while chemical surface composition characterization by X-ray photoelectron spectroscopy (XPS) showed the presence of Bi, Fe, O and the doping element Ba. Absorption measurements allowed us to determine the energy band gap of the films, while photoluminescence measurements have shown the presence of oxygen vacancies, which are responsible for the enhanced photocatalytic activity of the material. Photocatalytic degradation experiments of Methylene Blue (MB), Methyl orange (MO), orange G (OG), Violet and Rhodamine B (RhB) performed on top of BBFO2 thin films under solar light showed the degradation of all pollutants in varying discoloration efficiencies, ranging from 81% (RhB) to 54% (OG), 53% (Violet), 47% (MO) and 43% (MB). Full article

Cement is one of the most widely used structural materials and serves as the primary component of concrete. Among the various types, Portland cement is the most commonly utilized due to its excellent strength and corrosion resistance. Recently, efforts have been made to incorporate various functional additives into Portland cement to impart new properties; however, studies on the resulting changes in corrosion resistance remain insufficient. While the existing research has largely focused on impurities in cement, systematic studies on the effects of interstitial elements on the crystallization and electrochemical behavior of cement are scarce. This study investigates the influence of carbon (C) addition on the crystallographic structure and electrochemical properties of Portland cement. C concentrations from 0 to 10 wt.% were added. The microstructure and crystallographic structure with different C concentrations were analyzed using FE-SEM and XRD. The bonding characteristics of cement components according to the C composition were measured using XPS, hardness was measured using Vickers hardness, and electroconductivity was calculated using a 4-point probe. The electrochemical behavior was evaluated according to the ASTM G 61 standards through OCP, EIS, and potentiodynamic polarization tests. As the composition of C increased, the number of voids and cracks decreased, while the electrical conductivity increased from 1.7 × 10⁻⁴ to 4.3 × 10⁻². Additionally, the resistance tended to decrease with the increase in C composition. Therefore, the concentration of C needs to be controlled depending on the required function of the cement. Full article

Discovering stable polymeric nitrogen phases and exploring their properties are crucial for energy storage and conversion, garnering significant attention. In this study, we investigate the formation possibility of a stable compound between Ar and N₂ through ab initio calculations under low-pressure conditions (0–100 GPa). The novel super nitride, Imm2 ArN_10, is designed to demonstrate robust thermodynamic stability under high pressures (91 GPa) and showcase the unique host–guest structure, in which guest atoms (Ar) are trapped inside the host polymeric N₁₀. Significantly, given the weak interaction between Ar and N atoms and a channel parallel to the c-crystallographic axis in ArN₁₀, we propose a novel method to stabilize the previously unknown polymeric nitrogen structure, Imm2-N₁₀, by removing the guest argon atoms from the natural channels of ArN₁₀. Imm2 ArN₁₀ and N₁₀ are thermodynamically and dynamically stable, with energy densities of 9.1 kJ g⁻¹ and 12.3 kJ g⁻¹, respectively—more than twice that of TNT. Additionally, ArN₁₀ and N₁₀ stand out as leading green energetic materials, boasting a superior explosion velocity of 17.56 km s⁻¹ and a detonation pressure of 1712 kbar, surpassing that of TNT. These findings significantly impact on the creation of pure nitrogen frameworks through chemical reactions involving inert elements under high pressure. Full article