Uniaxial Texture Research Articles

Exploring the influence of anisotropy and microstructure of the sintered Nd-Fe-B magnet using nanoindentation and scratching tests

This study evaluated the influence of magnetic anisotropy and microstructure on the mechanical properties and material removal mechanism of anisotropic sintered Nd-Fe-B magnet. Nanoindentation tests were performed to measure the hardness (H), elastic (Es) and shear (G) modulus on two faces and main phases of the Nd-Fe-B material. To understand the contribution of the Nd2Fe14B1 and Nd-rich phases on material removal mechanism, scratching tests were also employed in the present study. Results showed that the Nd-Fe-B exhibits magnetic anisotropy with a high degree of uniaxial texture. Fracture analysis on the parallel and perpendicular faces related to the c-axis revealed no difference in fracture mechanisms. The load-displacement curves indicated that there is similar elastoplastic deformations induced by the penetration of indenter on the analyzed faces. Although Nd-Fe-B exhibits high magnetic anisotropy, the mechanical properties obtained from the two faces studied had not statistic difference. Nd-Fe-B is composed of hard and soft phases, where the Nd2Fe14B1 grain exhibited H = 12.5 ± 0.5 GPa, Es = 191.6 ± 12.6 and G = 77.3 ± 5.1 GPa, whereas the Nd-rich phase had values of H = 6.5 ± 0.7 GPa, Es = 124.0 ± 12.3 GPa and G = 50.0 ± 4.8 GPa. The Nd2Fe14B1 and Nd-rich phases strongly influenced scratch groove formation, being observed intergranular microcrack, replacement of Nd2Fe14B1 grain and bulging of Nd-rich grain boundaries. The mechanical properties of the Nd-Fe-B magnet were not affected by magnetic anisotropy or the high degree of uniaxial texture. However, the Nd2Fe14B1 grain presents higher hardness, elastic and shear modulus than the Nd-rich phase. Such characteristics can affect the machined surface formation when employing abrasive machining processes.

Tailoring the electronic properties of the SnO2 nanoparticle layer for n-i-p perovskite solar cells by Ti3C2TX MXene

The effect of the Ti3C2Tx MXene modification of the SnO2 electron transport layer (ETL) was studied for the concentration range 0–7.4 wt% MXene. The electronic properties of the MXene-modified ETL were studied by the electrical conductivity measurements, density of states mapping by the energy-resolved electrochemical impedance spectroscopy, ultraviolet photoelectron spectroscopy, and photoluminescence. The structure and morphology of the MXene-modified ETL and the top perovskite layer were analyzed by the scanning electron microscopy (SEM), scanning transmission electron microscopy, grazing-incidence X-ray diffraction and in situ grazing-incidence wide-angle X-ray scattering (GIWAXS). The increased electrical conductivity and electron selectivity for the MXene-modified SnO2 ETL was confirmed up to 1 wt% MXene. For 7.4 wt% MXene, significant suppression of the hole blocking property of the ETL was found. The in situ GIWAXS was performed during the post-deposition annealing of the perovskite layer. The increased perovskite grain size on the SnO2 ETL modified by MXene compared to the pure SnO2 ETL visible by SEM was confirmed. The uniaxial texture of the perovskite crystals was revealed in both cases with an increased misorientation angle for the MXene-modified ETL. The grain size and misorientation angle do not exhibit any systematic temporal changes during the post-deposition annealing. The increasing number of the grains during the annealing was observed. These results are explained using the nucleation and growth model. The increased power conversion efficiency from 17.4% to 18.3% of the archetypal methylammonium-lead-iodide perovskite solar cell after the modification of the SnO2 ETL with 0.1 wt% MXene is the effect of two contributions - increased electrical conductivity of the ETL and improved crystallinity and larger grain size compared to the pure SnO2 ETL, which lowers the total boundary area and charge recombination at trap states typically formed at grain boundaries.

The Comparison of the Effect of Flour Particle Size and Content of Damaged Starch on Rice and Buckwheat Slurry, Dough, and Bread Characteristics

The effect of botanical origin, the flour particle size, and the content of damaged starch on flour pasting properties, dough behavior during a uniaxial deformation test, and bread characteristics were evaluated on rice and buckwheat flours. The rice flour with a median particle size D(0.5) of 60.2, 70.6, 106.8, and 189.4 μm, and buckwheat flour with a D(0.5) of 56.4, 68.4, and 95.8 μm were prepared using the same milling technology. The botanical origin of the flours was the strongest factor influencing the flour pasting properties, stress accumulated in dough during the uniaxial deformation test, loaf characteristics, texture, and sensory characteristics of breads. The flour particle size significantly influenced mainly the flour pasting properties. The effect of the content of damaged starch was the weakest among the studied factors. The flour particle size and the content of damaged starch were closely related. The flour botanical origin was the strongest factor; therefore, it seems not to be possible to predict the bread-baking potential of gluten-free flours based on the results obtained for flour of a different botanical origin. More research on flours from different plants prepared by the same milling process is required to support this hypothesis.

Room temperature positive exchange bias in CoFeB/D019-Mn3Ge noncollinear antiferromagnetic thin films

Polycrystalline and single crystal antiferromagnetic D019-Mn3Ge thin films were grown by magnetron sputtering on GaN (0001) and Pt (111) templates at different substrate temperatures. Later, a CoFeB layer was grown on top of the D019-Mn3Ge films at room temperature. Single crystal D019-Mn3Ge thin films, with high surface roughness, induced an increase of the coercivity of the CoFeB ultrathin films, meanwhile polycrystalline D019-Mn3Ge thin films, with uniaxial texture and low surface roughness, induced positive exchange bias at room temperature by cooling the sample under a magnetic field of 2 T. No exchange bias was observed with lower cooling magnetic fields. The non-zero magnetic moment of uncompensated D019-Mn3Ge grains of the textured films couple antiferromagnetically leading to positive exchange bias.

Estimation of texture and anisotropy field in a NdDyFeCoB magnet by magnetic measurements at the perpendicular direction

A reliable method for estimating the anisotropy field in samples with uniaxial texture distribution is presented and discussed. From experimental measurements of the hysteresis in VSM (Vibrating Sample Magnetometer) at the parallel and perpendicular direction (using as reference the direction of alignment of the sintered magnet), and with the simultaneous fitting of the 1st quadrant in the region of reversible rotation of the measured hysteresis, the anisotropy field, magnetization of saturation and the crystallographic texture were determined. The examined magnet was a NdDyFeCoB magnet, with the proportion between the 5 main alloying elements represented by the atom% formula: (Nd8.6Dy4.9)(Fe81,1Co4,1Cu1,3). The crystallographic texture of the magnet can be described by a Gaussian distribution. It was found Mr/Ms = 0.969 representing the crystallographic texture of the magnet. The anisotropy field of the examined (NdDy)(FeCoCu)B sample was estimated as 111 kOe. The coercivity of the sample is very high, 43.8 kOe. The coercivity is 63.6% of the theoretical maximum predicted by the anisotropic Stoner-Wohlfarth Model.

Oblique angle co-deposition of nanocolumnar tungsten thin films with two W sources: Effect of pressure and target current

Two series of tungsten thin films are sputtered on silicon and glass substrates by oblique angle co-deposition technique with an original configuration. Two opposite distinct tungsten targets are simultaneously used, both tilted with an oblique angle of 80°. The growth is performed at low (0.33 Pa) and high (1.5 Pa) argon sputtering pressure and the current intensity applied to the targets varies between 50 and 250 mA. The effect of these deposition parameters on the films microstructure and electrical properties is investigated by scanning and transmission electron microscopy, X-ray diffraction and pole figures, and van der Pauw method. Due to self-shadowing effect, all tungsten sputtered thin films are porous and columnar. At low pressure, the columnar tilt angle β can be tuned with the target current intensity until obtaining vertical columns. X-ray diffraction and pole figure analyses point out a A15 crystal structure (β-W) and a uniaxial fiber texture with a <100> growth direction. In contrast, tungsten thin films deposited at high pressure present a cauliflower structure and are poorly crystallized. Both deposition parameters also affect the films electrical resistivity and anisotropy. These behaviors are discussed and linked to the microstructure and crystallography.

The Effect of Steaming Time on the Textural Characteristics of Two Sweet Potatoes with Different Flesh Colors

&lt;p&gt;Sweet potatoes have varied physical characteristics based on their flesh colors. Two selected sweet potato (SP) with white (WF) and yellow-fleshed (YF) colors were collected from local market and analyzed their textural characteristics using a Uniaxial compression and Texture Profile Analysis (TPA) test. The study was conducted in the Food Processing Technology Laboratory, Faculty of Food Science Technology, University of Putra Malaysia. All textural attributes were collected from the samples treated with steaming for 5, 10, 15 and 20 min. The moisture content of the samples were determined before and after steaming. The results showed that the moisture content of WF was lower than YF both before and after steaming, which could be declared as a typical moisture content for each flesh color. This resulted in a greater peak deformation or firmness of the fresh tuber found in WF relative to YF. Steaming SP for 5 min exhibited the “raw” properties tissue, whereas steaming for more than 10 min would generate the “cooked” tissue that significantly affected the textural characteristics. The hardness level decreased considerably along with the time of steaming and was similar for both flesh colors after 15-min steaming. The WF was less adhesive and less elastic; however, it had less chewiness than that of YF. This suggests that the use of WF as a raw material for mashed products would have advantages, such as easiness to mash, less tendency to stick with the cooking tools, and less elastic. &lt;br /&gt;&lt;br /&gt;&lt;/p&gt;

Synthesis of textured films of hexagonal barium ferrite on Al2O3/Si3N4 amorphous structure

In this work structural studies of BaFe12O19/Al2O3/Si3N4 thin films with different thicknesses of aluminum oxide and silicon nitride are represented. It is shown that barium hexaferrite crystallizes on the amorphous surface of aluminum oxide with spontaneously formed (00l) uniaxial texture. Microstructural differences in BaFe12O19 films were observed with varying of the thickness of amorphous sublayers, which is explained by the effect of mechanical stress.

Conundrum of strongly coupled supercurrent flow in both under- and overdoped Bi-2212 round wires

Understanding what makes Bi$_2$Sr$_2$Ca$_1$Cu$_2$O$_x$ (Bi-2212) the only high critical current density ($J_c$), high temperature superconductor (HTS) capable of being made as a round wire (RW) is important intellectually because high $J_c$ RW Bi-2212 breaks the paradigm that forces biaxially textured REBCO and uniaxially textured (Bi,Pb)$_2$Sr$_2$Ca$_2$Cu$_3$O$_x$ (Bi-2223) into tape geometries that reproduce the strong anisotropy of the native crystal structure and force expensive fabrication routes to ensure the best possible texture with minimum density of high angle grain boundaries. The biaxial growth texture of Bi-2212 developed during a partial melt heat treatment should favor high $J_c$, even though its $\sim$15$^{\circ}$ full width at half maximum (FWHM) grain-to-grain misorientation is well beyond the commonly accepted strong-coupling range. Its ability to be strongly overdoped should be valuable too, since underdoped cuprate grain boundaries are widely believed to be weakly linked. Accordingly, we here study property changes after oxygen underdoping the optimized, overdoped wire. While $J_c$ and vortex pinning diminish significantly in underdoped wires, we were not able to develop the prominent weak-link signature (a hysteretic $J_c$(H) characteristic) evident in even the very best Bi-2223 tapes with a $\sim$ 15$^{\circ}$ FWHM uniaxial texture. We attribute the high $J_c$ and lack of weak link signature in our Bi-2212 round wires to the high-aspect ratio, large-grain, basal-plane-faced grain morphology produced by partial-melt processing of Bi-2212 which enables $c$-axis Brick-Wall current flow when $ab$-plane transport is blocked. We conclude that the presently optimized biaxial texture of Bi-2212 intrinsically constitutes a strongly coupled current path, regardless of its oxygen doping state.

Texture Formation in Polycrystalline Thin Films of All-Inorganic Lead Halide Perovskite.

Controlling grain orientations within polycrystalline all-inorganic halide perovskite solar cells can help increase conversion efficiencies toward their thermodynamic limits; however, the forces governing texture formation are ambiguous. Using synchrotron X-ray diffraction, mesostructure formation within polycrystalline CsPbI2.85 Br0.15 powders as they cool from a high-temperature cubic perovskite (α-phase) is reported. Tetragonal distortions (β-phase) trigger preferential crystallographic alignment within polycrystalline ensembles, a feature that is suggested here to be coordinated across multiple neighboring grains via interfacial forces that select for certain lattice distortions over others. External anisotropy is then imposed on polycrystalline thin films of orthorhombic (γ-phase) CsPbI3- x Brx perovskite via substrate clamping, revealing two fundamental uniaxial texture formations; i)I-rich films possess orthorhombic-like texture (<100> out-of-plane; <010> and <001> in-plane), while ii) Br-rich films form tetragonal-like texture (<110> out-of-plane; <110> and <001> in-plane). In contrast to relatively uninfluential factors like the choice of substrate, film thickness, and annealing temperature, Br incorporation modifies the γ-CsPbI3- x Brx crystal structure by reducing the orthorhombic lattice distortion (making it more tetragonal-like) and governs the formation of the different, energetically favored textures within polycrystalline thin films.

Texture and magnetic anisotropy of YBa2Cu3O7-x film on MgO substrate

The texture and magnetic anisotropy of a YBa2Cu3O7-x (YBCO) film growth onto a MgO substrate are analyzed in order to understand the relation between them. X-ray diffraction shows the presence of the (00l) reflections from the YBCO layer with a grain’s fraction value 98%. Rocking Curves (RC) measurements reveal an out-of-plane texture with a full width at the half maximum of 0.81°, revealing a high uniaxial texture in the YBCO film. The temperature dependence of the susceptibility measurements obtained under many applied fields along Hext ||c-axis and Hext||ab-plane reveals strong relationship between the uniaxial texture and the magnetic anisotropy, confirming the high ordering of the CuO2 superconducting planes. In addition, the critical current density values are obtained from the hysteresis loops and compared to similar YBCO films with uniaxial and biaxial texture reported elsewhere.

Analytical expressions to estimate the effective piezoelectric tensor of a textured polycrystal for any crystal symmetry

This work introduces a set of analytical expressions that simplifies the procedure of obtaining closed-form formulas to estimate the effective piezoelectric properties of polycrystalline aggregates formed by crystals of all the 21 non-centrosymmetrical classes and with arbitrary textures. The expressions are derived from orientational averages of third-order piezoelectric tensors of the individual crystals that are weighted by orientational distribution functions. The averaging is done by using generalized spherical harmonic series expansions. Improvements with respect to previous works in the literature are twofold: all crystal symmetries are considered and no symmetry restrictions are imposed to texture. The versatility of the introduced expressions is demonstrated on an example of BaTiO3 polycrystals with uniaxial and biaxial textures characterized by single and double Gaussian distributions, respectively. The results for uniaxial texture are in perfect agreement with the results published in the literature. The biaxial texture is discussed in detail and analyzed for a set of limiting cases.

Strain-rate-sensitive mechanical response, twinning, and texture features of NiCoCrFe high-entropy alloy: Experiments, multi-level crystal plasticity and artificial neural networks modeling

The present work adopts an extended multi-level crystal plasticity finite element method (CPFEM) framework coupled with an improved artificial neural network (ANN) algorithm to predict the quasi-static and dynamic uniaxial tensile mechanical response, twinning and texture characteristic in NiCoCrFe high-entropy alloy. Firstly, a Split-Hopkinson tensile bar setup is utilized to achieve high strain rates, and the initial microstructure and texture data used in CPFEM is characterized by electron backscattered diffraction. The experimental results show the effect of twins on strain hardening is more obvious with the increase of strain rates. Next, a developed dislocation-density based hardening law taking into account rate and temperature sensitive property is firstly extended by calculating the slip/twin activation stresses through thermal activation mechanism, Hall-Petch resistance, forest dislocation drag and slip-twin interactions. The simulations reveal some underlying defect mechanisms using the temporal evolution of microstructure and macro response over a wide range of strain rates. Then, an advantageous ANN model combined with the Genetic algorithm (GA) optimized is applied to exploit potential law of massive experimental and CPFEM data and serve engineering applications efficiently. The verification results capture well the features of strain rate sensitivity with CPFEM and experimental data sources. Finally, the predictive ability of two models is further demonstrated by validating the uniaxial tension of NiCoCrFe HEA. It is clear that the improved idea (an ANN model through GA optimization) is more efficient than the physical mechanism based CPFEM model.

Optimization of co-sputtered CrxAl1−xN thin films for piezoelectric MEMS devices

CrAlN alloys can play an important role in the improvement of next generation piezoelectric MEMS devices. However, enhanced piezoelectric constants require high degree of uniaxial orientation in the polycrystalline thin film. In this work, CrxAl1−xN thin films with varying compositions were deposited at different substrate temperatures by reactive DC co-sputtering technique and compared with respect to their microstructure and optical properties. The relationship between the atomic composition of the layers and the plasma powers over the Al and Cr targets during co-sputtering was revealed accurately by Rutherford backscattering spectrometry. As it was found by X-ray and selective area electron diffraction methods, thin films in the range of x = 0–0.23 show hexagonal wurtzite-type phase, which changes to cubic rock-salt-type structure between 0.23 < x < 0.31. At lower Cr cation concentration, like x = 0.12 the wurtzite-type polycrystalline film indicates uniaxial texture, whereas it is almost randomly oriented at x = 0.23. Among the compared compositions, Cr0.12Al0.88N showed the strongest c-axis orientation, whereas the optimal substrate temperature was found to be T = 350 °C. While the refractive index measured by ellipsometry increases monotonously from 2.07 to 2.64 with increasing Cr cation concentration in the range of x = 0–0.31, the optical bandgap shrinks from 2.65 to 2.23 eV. These optical data can provide references for future contactless wafer-scale optical monitoring process.

Development of Corn Fiber Gum–Soybean Protein Isolate Double Network Hydrogels Through Synergistic Gelation

Corn fiber gum (CFG)–soybean protein isolate (SPI) double network (DN) hydrogel was fabricated under the action of laccase and D-(+)-gluconic acid δ-lactone (GDL) at room temperature. Time sweep dynamic rheological analysis indicated that laccase and GDL work synergistically to enhance the gel strength of CFG-SPI DN hydrogels. The gel strength of CFG-SPI DN hydrogel was higher than those of hydrogels prepared by either constituent. Uniaxial compression test and texture profile analysis showed that CFG-SPI DN hydrogel integrated the mechanical properties of CFG and SPI networks, whose fracture strain was 20 times higher than that of CFG hydrogel, while the hardness was about twice the value that of SPI hydrogel. Scanning electron microscopy observation confirmed that both CFG and SPI participated in the formation of CFG-SPI DN hydrogel. CFG-SPI DN hydrogel showed a more regular and denser microstructure as compared with hydrogels prepared by single constituent. CFG-SPI DN hydrogels with various mechanical properties, water-holding capacities and microstructures were prepared by controlling the concentrations of CFG and SPI. Among which, CFG-SPI double network hydrogel with 7.0% SPI and 1.0% CFG exhibited the highest hardness and water-holding capacity.

Structure and Orientation Variations during Growth of Films of Pd–5 at % Pb Solid Solution

This article is devoted to studying morphological, structural, and orientation transformations and variations of elemental composition during growth of films of Pd–Pb solid solution upon magnetron sputtering of Pd–5 at % Pb target in an Ar environment (10–1 Pa); the initial vacuum is 10–3 Pa; growth rate is 4 nm/s; magnetron power during growth of thin films is 630–650 W and of thick films is 750–790 W. It is established that nucleation and growth of films of Pd–Pb solid solution take place according to the Volmer–Weber growth mode and are accompanied by collective recrystallization. The stage of labyrinth morphology is achieved at an average thickness of 10 nm. This stage is characterized by nanocrystalline structure and uniaxial texture 〈 111〉 . Existence of the second component (Pb) suppresses multiple twinning peculiar to Pd island films. The elemental composition in the film bulk is characterized by a decrease in Pb concentration.

Texture Gradient in a Rectangular Extruded Al60Mg40 Metal Matrix Composite

By applying cold extrusion, an elemental metal powder composite Al60Mg40 was prepared. The texture gradient was measured over the cross-section of the extrusion profile using synchrotron radiation while the bulk texture was obtained by neutron diffraction. The aluminum phase shows a typical texture component of plane-strain deformation in the middle part of the sample and a uniaxial deformation texture at the surface. In the central region of the extruded bar, the (0002) Mg pole figure shows a split along the extrusion direction (±ED), which also has been observed in rare-earth containing magnesium alloys. These two poles twist towards the transverse direction on moving towards the surface of the extruded bar; one pole moves to +TD and the other one to −TD. The angle of twist increases towards the TD surface.

Investigations into the phase composition of zirconia-based sinters with an axial texture

Owing to the phase transition of the tetragonal form of ZrO2 into the monoclinic one, caused by mechanical stresses, preparation of powder samples for quantitative phase analysis by the X-ray diffraction method should be avoided. The process of grinding of zirconia sinters leads to considerable changes in their phase composition. For this reason, a quantitative phase analysis should be conducted on solid samples not subjected to mechanical stresses, irrespective of problems appearing during experiments and analysis. One such problem is preferred crystallographic orientation (texture). This paper describes the influence of a preferred crystallographic orientation on the quantitative phase analysis conducted on solid samples and presents the results of an analysis in which corrections for uniaxial and multiaxial textures were applied. It was found that the examined samples had a very weak but nonzero multiaxial texture. The share of the randomly oriented fraction in the examined sinters was determined to be ca 94 vol.% and the share of the textured fraction ca 6 vol.%. From the statistical point of view, in the case of small amounts of the textured fraction, a correction on one distinguished crystallographic plane can overcome this problem. In the case of the slightly textured sinters of metering nozzles subjected to investigation here, the correction related to all the unique directions was statistically insignificant because the textured part corresponds to only a small volume fraction. However, corrections related to all texture axes considerably improve the fit of the calculated X-ray pattern with the experimental one and help to better characterize the examined materials.

Consumer perceptions, descriptive profile, and mechanical properties of a novel product with chickpea flour: Effect of ingredients.

Increasingly popular in the West is hummus, a spread that is made with pureed chickpeas and other healthful ingredients. The changes in texture measurements and sensory properties in a novel chickpea flour-based product occurring when water is partially replaced by common ingredients of hummus were investigated. Eleven chickpea gels containing different amounts of minced garlic, lemon juice, curry powder, and inulin were prepared and compared with two control gels. These ingredients were chosen to make the product tastier, appealing, and similar to hummus. Instrumental texture tests were carried out: uniaxial compression, stress relaxation, and texture profile analysis. Quantitative descriptive analysis was used to describe differences in sensory properties perceived by a trained panel, whereas repertory grid method combined with free choice profile was used to determine differences perceived by untrained consumers. Gels with higher curry powder content presented lower force to breakdown, whereas increasing inulin content led to gels with higher hardness. Principal component analysis was applied to instrumental parameters and quantitative descriptive analysis data, whereas generalized Procrustes analysis was applied to free choice profile data. This newly developed chickpea gel may make a nutrition claim with respect to protein ("high in protein," or at least a "source of protein").

Preparation of double‐network tofu with mechanical and sensory toughness

SummaryIn this study, sugar beet pectin and soy protein were used to prepare the double‐network (DN) modified‐tofu by sequential laccase and microbial transglutaminase treatments. The mechanical properties of modified‐tofu were analysed by uniaxial compression test and texture profile analysis. The DN modified‐tofu exhibited greater mechanical toughness than the corresponding single‐network modified‐tofu, while the ratio of soy glycinin to soy protein isolate reached and exceeded 50%. The enhancement of mechanical toughness may be mainly ascribed to the hierarchical microstructure which is observed in DN modified‐tofu by scanning electron microscopy. DN modified‐tofu provided a distinctive mechanical and sensory tough texture as compared to other tofu samples. In addition, the oral processing measurements indicated that DN modified‐tofu required higher jaw‐closing muscle activities, a greater number of chews and longer chewing duration to be processed. Furthermore, the chewing pattern of DN modified‐tofu was different from other tofu samples.