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Underwater friction stir welding (UwFSW) of dissimilar brass (CuZn40) and aluminum (AA1100-O) joints have a more pronounced effect on the microstructure and crystallographic texture evolution than classical open-air friction stir welding (C-AFSW). In this research, the microstructure and texture evolution mechanism across the weld thickness and different FSW zones are studied. Cross-section of the weld joints developed by UwFSW and C-AFSW were investigated via transmission electron microscopy (TEM) and electron backscattered diffraction (EBSD). EBSD data of C-AFSW joints reveal that significant grain refinement occurs in the stirred zone (SZ) due to continuous dynamic recrystallization. As compared to C-AFSW, the microstructural evolution mechanism in UwFSW was found to be very complex in the different parts of the SZ. For UwFSW, discontinuous dynamic recrystallization and geometric dynamic recrystallization were found to be the main microstructural evolution mechanism in the SZ. In addition, the enhanced cooling rates of UwFSW produce a fine grain structure and a large number of high angle boundaries (HABs). Both C-AFSW and UwFSW showed mixed grain structure in the thermomechanically affected zone. TEM results showed dislocation accumulation and annihilation were predominant in UwFSW with fine and denser rod-shaped (θ́-Al2Cu) precipitates. The shear textures A / A ¯ , A1*/A2* and B / B ¯ are formed in the SZ of both C-AFSW and UwFSW. However, the shear components B / B ¯ dominates in the C-AFSW as compared to A / A ¯ . The result and findings of this research help to understand the microstructure evolution mechanism of CuZn40/AA1100-O FSW joints and further optimize the welding process for application. [ABSTRACT FROM AUTHOR]

The thermo-stability of microstructure during isothermal annealing at 900 °C and 1000 °C in a cold-worked Cu-Al2O3 composite with 0.1 wt.% Al content and its effect on resistance to softening were investigated in this paper. The results reveal that the microstructure following cold deformation consists of a Cu matrix with a refined grain size and high-density dislocations, accompanied by dispersed Al2O3 nanoparticles exhibiting an extremely low volume fraction. During isothermal annealing at 900 °C, the Al2O3 nanoparticles can strongly restrict the migration of the dislocations and suppress the recrystallization of the fine-grained Cu matrix by the Zener pinning effect. Furthermore, the presence of pinned dislocations facilitates the formation of sub-grain boundaries comprising high-density dislocations. Consequently, the Cu-Al2O3 composite with 0.1 wt.% Al content exhibits remarkable thermo-stability in its microstructure due to the incorporation of Al2O3 nanoparticles, resulting in a significantly elevated softening temperature of up to 1000 °C and thereby demonstrating excellent resistance against softening. However, the observed phenomenon of softening after isothermal annealing at 1000 °C for 5 hours can be attributed to extensive recrystallization growth that promotes twin boundary formation, primarily caused by the weakening Zener pinning effect resulting from Oswald ripening of Al2O3 and rod-like Al2O3 formation.

In this research paper, the factors impacting electrical conductivity of the flexible graphite foils (GFs) produced by different forming processes, namely, either by rolling or pressing, were studied. The relationship between electrical conductivity and texture and structure that formed when producing the material was examined. Correlation was determined between the texture sharpness and anisotropy of electrical conductivity, as well as the extent of impact from the substructural characteristics on the properties' values. Besides, it was demonstrated that the higher values of micro-strains, as well as the secondary phase substructure, reduced conductivity in foils. Electrical conductivity calculation was optimized for different directions in foils using the Kearns texture parameters and taking into consideration the foil structural characteristics. [ABSTRACT FROM AUTHOR]

Recently, metal additive manufacturing (AM) has enabled a wide range of control over metallurgical structures. Originally, the unique manufacturing method of stacking tiny melted sections to fabricate products with complex shapes with high precision provided geometrically defined solidification units with specific solidification directions and steep cooling, which in turn enabled the control of the metallurgical microstructure. This article describes the work of the author’s research group on crystallographic texture control via laser powder bed fusion (LPBF), including (1) the influence of powder properties on the formation of dense products, which is essential for crystallographic texture formation; (2) the influence of melt pool shape and crystallographic characteristics of the materials on single crystal formation and determination of crystal orientation; and (3) the success of “Alloy Design” for a highly functional single crystalline bio-high-entropy alloy (BioHEA) considering specific solidification fields under LPBF. [ABSTRACT FROM AUTHOR]

Compositional and anatomical studies of silicified wood have been carried out extensively all around the world. The classification of silicified wood as such deals with all the forms and phases of silica that come under its umbrella. One such class of silicified wood is fossil wood with a high content of quartz, and there are very limited mentions of this category of fossilized wood. The examined wood belongs to gymnosperm and comes from the Upper Triassic deposits of Madagascar. A fresh approach to such samples is adopted by studying the crystallographic texture of the fossil wood to understand the orientation of the crystals replacing the organic matter within the sample. This work focuses on crystallographic texture analysis based on pole figures measured by X-ray diffraction. The intensity of the pole density maxima on the pole figures measured on the heartwood surface part of the analyzed samples is higher than that on the sapwood. This affirms that the crystallographic texture is sharper at the heartwood part compared to the sapwood. The X-ray tomography study, conducted to understand the difference in mineral distribution within the sample, reveals a greater X-ray absorbing phase on the sapwood of both samples. This is due to the concentration of iron compounds, which both replace the remaining conductive structures of the wood and fill the cavities inside them. We believe that this research on silicified wood is the first research work that encompasses crystallographic texture analysis with pole figures, an approach not previously undertaken in similar studies. We hope that our research can be useful in understanding the processes of replacement of organic matter by minerals. [ABSTRACT FROM AUTHOR]

This study demonstrated the unique crystallographic features in Al 2 O 3 /YAG eutectic by seed-crystal inducing in laser floating zone melting (LFZM) process for crystallographic orientation control. The as-fabricated eutectic ceramics induced by different single crystalline seeds were mainly composed of randomly oriented Al 2 O 3 faceted particles and irregular eutectic, as a result of the initial uncoupled growth at the junction of seed and eutectic. Specifically, along the direction of directional solidification, the eutectic ceramics grew stably with a single crystallographic orientation relationship with low planar disregistry (2 %∼6 %). The stability of phase interface with minimum interfacial strain and better ionic charge balance in Al 2 O 3 /YAG eutectic has a greater effect on the regulation of the eutectic growth orientation than the constraint of the single crystalline seed. [ABSTRACT FROM AUTHOR]

Energy‐dispersive Laue diffraction (EDLD) is a powerful method to obtain position‐resolved texture information in inhomogeneous biological samples without the need for sample rotation. This study employs EDLD texture scanning to investigate the impact of two salivary peptides, statherin (STN) and histatin‐1 (HTN) 21 N‐terminal peptides (STN21 and HTN21), on the crystallographic structure of dental enamel. These proteins are known to play crucial roles in dental caries progression. Three healthy incisors were randomly assigned to three groups: artificially demineralized, demineralized after HTN21 peptide pre‐treatment and demineralized after STN21 peptide pre‐treatment. To understand the micro‐scale structure of the enamel, each specimen was scanned from the enamel surface to a depth of 250 µm using microbeam EDLD. Via the use of a white beam and a pixelated detector, where each pixel functions as a spectrometer, pole figures were obtained in a single exposure at each measurement point. The results revealed distinct orientations of hydroxyapatite crystallites and notable texture variation in the peptide‐treated demineralized samples compared with the demineralized control. Specifically, the peptide‐treated demineralized samples exhibited up to three orientation populations, in contrast to the demineralized control which displayed only a single orientation population. The texture index of the demineralized control (2.00 ± 0.21) was found to be lower than that of either the STN21 (2.32 ± 0.20) or the HTN21 (2.90 ± 0.46) treated samples. Hence, texture scanning with EDLD gives new insights into dental enamel crystallite orientation and links the present understanding of enamel demineralization to the underlying crystalline texture. For the first time, the feasibility of EDLD texture measurements for quantitative texture evaluation in demineralized dental enamel samples is demonstrated. [ABSTRACT FROM AUTHOR]

Mechanical properties of weldments, as required to be explored for optimizing strength and toughness of weldments, the role of crystallographic texture to contribute in special characteristics, defining structure-properties of weldments, especially hardness and toughness, require the specific knowledge in concerned crystallographic textures. Aerospace technology and associated cleaner fabrication techniques, generally have increased the loyalty to FSW techniques in engineering sectors, to characterize the strength and toughness of weldments, with privileged validity. Wide compositional partitioning and less feeding range, are generally alleviated in Electron Beam Welding, EBW, the best to replace FSW for fabricating precision components, while for large structural components, the speed of job accomplishments in time, is by FSW, as the alternative. [ABSTRACT FROM AUTHOR]

Depending on the 3D-printing orientation, the anisotropy of the elastic characteristics of the Inconel 625 alloy generated with selective laser sintering from powders is investigated. The impact of the original powder combination and the following heat treatment (post-printing treatment) on the anisotropy of the alloy elastic characteristics is assessed. As demonstrated, the suggested treatments can lessen the anisotropy of the alloy elastic characteristics. Based on knowledge of the elastic constants of the single crystal and x-ray texture features, the results of a theoretical estimation of the elastic and shear moduli, Poisson’s ratio, and their anisotropy in the horizontal and vertical directions of 3D printing are provided. As demonstrated, the obtained theoretical values differ by 6–10% from the corresponding experimental values. The calculated stress–strain state can be more accurately calculated with the use of the estimated elastic characteristics and their anisotropy. The strategy for 3D-printing complicated components from Inconel 625 alloy may be made more effective.

The paper covers the production, analysis of the microstructure, crystallographic texture and deformation mechanisms of the ultrafine-grained (UFG) Zn–1%Mg–1%Fe zinc alloy demonstrating unique physical and mechanical properties compared to its coarse-grained analogues. The zinc alloy with improved mechanical properties was developed in two stages. At the first stage, based on the analysis of literature data, an alloy with the following chemical composition was cast: Zn–1%Mg–1%Fe. Then, the alloy was subjected to high-pressure torsion (HPT) to improve mechanical properties, due to grain structure refinement, and implementation of dynamic strain aging. The conducted mechanical tensile tests of the samples and assessment of the alloy hardness, showed that HPT treatment leads to an increase in its tensile strength to 415 MPa, an increase in hardness to 144 HV, and an increase in ductility to 82 %. The obtained mechanical characteristics demonstrate the suitability of using the developed alloy in medicine, as some implants (stents) requiring high applied loads. To explain the reasons for the improvement of the mechanical properties of this alloy, the authors carried out comprehensive tests using microscopy and X-ray diffraction analysis. The microstructure analysis showed that during the formation of the ultrafine-grained structure, a phase transition is implemented according to the following scheme: Zneutectic + Mg2Zn11eutectic + FeZn13 → Znphase + Mg2Zn11phase + MgZn2particles + Znparticles. It was found that as a result of high pressure torsion in the main phases (Zn, Mg2Zn11), the grain structure is refined, the density of introduced defects increases, and a developed crystallographic texture consisting of basic, pyramidal, prismatic, and twin texture components is formed. The study showed that the stability of pyramidal, prismatic and twin texture components at the initial stages of high-pressure torsion, determines the level and anisotropy of the strength properties of this alloy. The relationship between the discovered structural features of the produced alloy and its unique mechanical properties is discussed.

In this study, we investigated the microstructural evolution of a Cu-0.13Sn-0.04Mg alloy that underwent heat treatment followed by room temperature rolling (RTR). Initially heat-treated specimens were rolled at room temperature (RT) with reduction ratios (RR) of 40% and 75% to perform microstructural and crystallographic textural analyses. Electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM) were utilise to examine both initial and deformed microstructures. Both exhibited heterogeneous microstructural distributions. Shear bands (SBs) existed in the initial specimen and became main sites for the nucleation of new grains during heat treatment. A denser presence of SBs was noted in the RTR specimens. Remarkably, an unusual self-annealing phenomenon was observed in these specimens, culminating in the emergence of recrystallized grains at RT. A plethora of such grains was observed in the severely deformed specimens, with numerous nucleating grains appearing proximal to the SBs or deformed grain boundaries (GBs). Time dependent microstructure evolution was observed via ex-situ EBSD technique in the compressed specimens. Formation of new grains, increase in high angle grain boundaries (HAGBs), and dislocation annihilations were observed with the progress of time. The crystallographic texture evolution in the initial specimen was predominantly influenced by the S component. At lower strains, the fractions of Copper component increased, whereas at higher strains, a greater fraction of Brass and S components were induced. Following a 40% RR, a saturation in hardness value was observed, which could be potentially attributable to an accelerated rate of RT recrystallization in the case of 75% RR. [ABSTRACT FROM AUTHOR]

In the multilayer thin-walled Inconel 625 alloy structures fabricated by the laser additive manufacturing (LAM) process, the poor plasticity of the interlaminar region often leads to structural fractures. In this paper, an oscillating LAM (O-LAM) technology using a transverse linear beam oscillation (LBO) process was proposed, and the effect of laser scanning speed on the forming accuracy, microstructure, crystallographic texture, and mechanical properties of interlaminar region was studied. The results show that the LBO process refined the grains and increased the number and length of high-angle grain boundaries in the interlaminar region. In addition, the LBO process with high laser scanning speed weakened the preferential orientation along the directions of laser scanning and deposition build-up. In particular, the dominant crystallographic textures of { 1 ¯ 10 } < 1 ¯ 1 ¯ 1 > and { 2 ¯ 21 } < 1 ¯ 1 ¯ 0 > in the interlaminar region were significantly reduced. The analysis of the Schmidt factor and the results of nano-indentation test show that the LBO process with high laser scanning speed reduced the stress concentration, and the elastic modulus and dislocation density in the interlaminar region. Therefore, the LBO process with high laser scanning speed can improve the plasticity and relieve the stress concentration of the interlaminar region, which is conducive to improving the overall mechanical properties of the Inconel 625 alloy multilayer thin-walled structure. [ABSTRACT FROM AUTHOR]

In this study, we present a systematic analysis of the relation between the structural properties and magnetic anisotropies of as-grown and heat-treated polycrystalline Fe 1 − x Ga x (0.11 < x < 0.19) thin films deposited on glass and Si(100) substrates. The results show that the crystallographic texture of the films has a significant impact on the evolution of the magnetic anisotropies. The samples grown on glass do not exhibit a preferred texture while, for samples grown on Si(100), the appearance of a weak in-plane fourfold magnetic anisotropy is reported. Such anisotropy is enhanced and better defined in the heat treated samples. Via a phenomenological model we show that this anisotropy has a microstructural origin. These findings demonstrate the possibility of tuning magnetic anisotropies by growing on different substrates and/or performing thermal treatments, which in turn reinforces the possibility of developing smart magnetic switching materials for electronic applications. [ABSTRACT FROM AUTHOR]

Rotation axes (together with rotation angles) are often used to describe crystal orientations and misorientations, and they are also needed to characterize some properties of crystalline materials. Since experimental orientation data are subject to errors, the directions of the axes obtained from such data are also inaccurate. A natural question arises: given the resolution of input rotations, what is the average error of the rotation axes? Assuming that rotation data characterized by a rotation angle ω deviate from the actual data by error rotations with fixed angle δ but which are otherwise random, the average error of the rotation axes of the data is expressed analytically as a function of ω and δ. A scheme for using this formula in practical cases when rotation errors δ follow the von Mises–Fisher distribution is also described. Finally, the impact of crystal symmetry on the determination of the average errors of the axis directions is discussed. The presented results are important for assessing the reliability of rotation axes in studies where the directions of crystal rotations play a role, e.g. in identifying deformation slip mechanisms. [ABSTRACT FROM AUTHOR]

The purpose of the study was experimental verification of the proposed concept of phase formation in electrocrystallised metals/alloys via the stage of supercooled liquid state. In accordance with the purpose, the task was to reveal the features of formation of the crystallographic texture in metals/alloys during their electrocrystallisation under the action of small force. The effect of the emergence of a new crystallographic texture with lower surface energy in metals/alloys during electrocrystallisation under the action of small external force exerted in the direction opposite to the initial axis of the texture was experimentally established. The obtained result is one more proof of the validity of the concept of phase formation in electrocrystallised metals/alloys via the stage of supercooled liquid state. [ABSTRACT FROM AUTHOR]

In the present study, Stainless steel 316L (SS316L) cylindrical specimens were fabricated at two different build orientations and two different laser powers using Laser powder bed fusion process (LPBF). Microstructural characterization such as XRD, SEM, EBSD analysis and tensile testing were carried out on fabricated specimens in stress relieved condition to understand the anisotropic behavior of LPBF printed specimens. Horizontally oriented specimens showed higher tensile strength when compared to vertically oriented specimens for both laser powers. XRD and EBSD phase maps did not reveal the presence of any secondary phases. However, build orientation and laser power affected the crystallite size of the samples. Bimodal grain structure comprising coarse columnar grains and fine equiaxed grains were observed from the micrographs. With variation in build orientation, there was a significant change in the average grain size of the specimens. High dislocation density was observed in horizontally oriented samples built at low laser power because of dislocation annihilation that can occur at high temperatures. However, EBSD analysis revealed random weak crystallographic texture which does not vary significantly with laser power or build orientation. Variation in grain size, grain morphology, sub-grain features and dislocation density are the reasons for the anisotropic tensile behavior observed in LPBF printed SS316L coupons in stress relieved condition. [ABSTRACT FROM AUTHOR]

The influence of the friction stir process (FSP) on the hole expansion formability of dual-phase 600 steel was examined by experimental and finite element analyses. Due to the microstructure of refining ferrite, martensite, and bainite, the yield strength and tensile strength increased after FSP by 95% and 63%, respectively. FSP led to the formation of (101) || ND and (111) || RD texture components in the processed zone. The observation of (111) || RD texture components in the FSPed steel resulted in an increment in the plastic strain ratio from 0.86 to 0.98. FSP provided a 20% improvement in the hole expansion ratio. The microstructural refinement and crystallographic texture played an important role in this increase. The FSP contributed to the increase in the hole expansion formability capability by delaying the crack formation during hole expansion and by causing the hole to fail at a higher load. It has been observed by experimental and finite element (FE) simulation results that the highest circumferential stress occurs at the hole edge where the main crack is formed. The FE simulation predictions agree with less than 2% error with the experimental observations. [ABSTRACT FROM AUTHOR]

Sm2Co14.75Fe1.5Ti0.75 nano-flakes have been prepared by surfactant-assisted ball milling (SABM) in the organic solvent of heptane with the surfactants of oleic acid. The effects of ball milling time on phase composition and magnetic properties were systematically studied. The experimental results show that the synthesized nano-flakes have an amorphous phase and a hexagonal 2:17-type crystalline phase with [00l] in-plane crystallographic texture induced by SABM without any external magnetic field. The coercivity value of the as-prepared nano-flakes was 5.0 kOe and then was enhanced to 6.0 kOe by the magnetic alignment for the sample ball-milled for 4 h. The remanence value of the un-aligned nano-flakes is lower than that of the magnetically aligned ones. In addition, the magnetically aligned nano-flakes exhibit a maximum energy product (BH)max of 56 kJ/m3 and a small misalignment angle θ of 11°, which is the best value ever reported. The magnetic anisotropy behavior was also observed in both aligned and un-aligned nano-flakes. [ABSTRACT FROM AUTHOR]

In classical texture analysis the orientation distribution function (ODF) is expanded as an infinite series of Wigner D -functions D m n l (⋅) , with the classical texture coefficients c m n l serving as undetermined expansion parameters. Herein we present a systematic procedure by which the classical expansion of an ODF (with arbitrary crystallite and texture symmetry) truncated at the order l = L can be directly rewritten as a tensorial Fourier expansion truncated at the same order, where the same set of classical texture coefficients c m n l appear as undetermined parameters. The crucial step of this procedure is as follows: Let H l be the complexified space of l -th order harmonic tensors and 〈 ⋅ , ⋅ 〉 the Hermitian inner product on H l . Let R be a rotation and R ⊗ l : H l → H l be the l -th order tensor product of R with itself. For each 1 ≤ l ≤ L , determine an orthonormal irreducible tensor basis B m l (− l ≤ m ≤ l) in H l so that D m n l (R) = 〈 B m l , R ⊗ l B n l 〉 for each rotation R . We have determined explicit sets of irreducible basis tensors B m l in H l for 1 ≤ l ≤ 8 , which are displayed in tables in this paper. In addition to examples which illustrate the general procedure, we provide, for orthorhombic aggregates of cubic and hexagonal crystallites, explicit expressions of tensorial Fourier expansions of the ODF up to terms with l = 8 , in which the tensorial texture coefficients are given in terms of the classical texture coefficients and the basis tensors B m l . [ABSTRACT FROM AUTHOR]

Depending on the 3D-printing orientation, the anisotropy of the elastic characteristics of the Inconel 625 alloy generated with selective laser sintering from powders is investigated. The impact of the original powder combination and the following heat treatment (post-printing treatment) on the anisotropy of the alloy elastic characteristics is assessed. As demonstrated, the suggested treatments can lessen the anisotropy of the alloy elastic characteristics. Based on knowledge of the elastic constants of the single crystal and x-ray texture features, the results of a theoretical estimation of the elastic and shear moduli, Poisson's ratio, and their anisotropy in the horizontal and vertical directions of 3D printing are provided. As demonstrated, the obtained theoretical values differ by 6-10% from the corresponding experimental values. The calculated stress-strain state can be more accurately calculated with the use of the estimated elastic characteristics and their anisotropy. The strategy for 3D-printing complicated components from Inconel 625 alloy may be made more effective. [ABSTRACT FROM AUTHOR]