Texture Transition Research Articles

Texture transition of shear bands in initially Goss–oriented grains in Fe–3 wt%Si alloy

Texture transition of shear bands in Goss–oriented grains of normalized Fe–3 %Si sheets with different diffused angles along φ2 axis during cold rolling was investigated by quasi in–situ electron back–scatter diffraction (EBSD) analysis. The diffused angle along φ2 axis of {111} 〈112〉 deformed matrix from initial Goss grains with φ2 axis diffusion below 10° decreases after cold rolling. Shear bands formed in {111} 〈112〉 deformed matrix have a similar diffusion along φ2 axis to the deformed matrix, and the diffused angle along φ1 axis is insignificant. The φ2–diffused angle evolution of shear band and deformed matrix in initially diffused Goss grains during cold rolling were analyzed using a crystal plasticity simulation.

Kinetics and energetics of room-temperature microstructure in nanocrystalline Cu films: The grain-size dependent intragrain strain energy

The fast kinetics of the low-temperature microstructure evolution in nanocrystalline metals requires an additional driving force from the excess intragrain energy in addition to the driving forces from the grain boundary energy, surface or interface energy, and thermal strain energy. If the excess volume of the grain boundary induces lattice distortions in grain interiors, the intragrain energy is the elastic-strain energy and can be determined from a grain-size-dependent strain model. Considering the available intragrain strain energy, we use transmission electron microscopy, x-ray diffraction line-broadening analysis, and theoretical models to investigate the kinetics and energetics of room-temperature nanostructure relaxation and abnormal grain growth in electroplated nanocrystalline Cu films devoid of thermal strains and high-density dislocations. The experimental data of grain sizes and microstrains are consistent with the theoretical size-dependent strain model. The limited nanostructure relaxation of Cu occurs with the grain boundary width reduction and intragrain strain release, which cannot alter the structural anisotropy and intrinsic high-energy state of nanograins. Based on quantitative descriptions of the variations in grain size, microstrain, and transformed fraction during abnormal grain growth, the possible driving forces and grain boundary mobility were systematically evaluated. The results indicate that the size-dependent intragrain strain energy provides a crucial driving force for rapid nanograin growth and texture transition, whereas the low nanograin boundary mobility in Cu films is probably correlated with the strained-lattice migration and faceted-boundary migration.

Residual stress evolution enhanced martensite phase transition and texture development in cryogenic-tempered WC-Co ultra-coarse grained cemented carbide

The aim of this study is to clarify the effect of residual stress on the microstructure, martensite phase transition of Co binder phase, texture development of WC hard phase and mechanical properties enhancement in cryogenic-tempered WC-6wt.%Co ultra-coarse grained cemented carbides. Sin2(ψ)-2θ method was used to analyze the residual stress, and EBSD was used to reveal the phase transition of Co phase and texture of WC phase. The results showed that the density, grain size and carbon balance of cemented carbide revealed little difference after cryogenic-tempering treatment. The mean compressive residual stress of WC phase increased by 60.84% after cryogenic treatment, while tempering treatment resulted in a significant relaxation of the residual stress by 101.97% and even transformed the compressive residual stress to tensile stress. EBSD analysis showed that the mean ratio of hcp-to-fcc Co increased from 1.75% to 4.22% and 11.61%. It is difficult to distinguish the effect of residual stress increase and the temperature decrease on the martensite transition during the cooling process. However, the occurrence of martensite phase transition during tempering is not temperature-dependent but highly related to the residual stress evolution. After cryogenic-tempering treatment, {0001}<11 2‾ 0> preferred orientation of WC phase was concentrated, which was related to the basal plane slip and grain deflection of WC grains during the evolution of residual stress. Due to the martensite phase transition strengthening of Co and the preferred orientation of WC, the mean Vickers hardness increased from 1068.4 HV30 to 1149.4 HV30. The mean transverse rupture strength firstly decreased from 2747.5 MPa to 2515.3 MPa, and then increased to 2705.0 MPa, which was related to the increase and relief of residual stress during the post treatment. Furthermore, mean fracture toughness showed a slight increase from 22.5 MPa m1/2 to 23.4 MPa m1/2. The simultaneous increase of fracture toughness with hardness can be attributed to the residual stress evolution and martensite phase transition.

Compartmentalized Janus droplets of photoresponsive cholesteric liquid crystals and poly(dimethylsiloxane)-based oligomers

A new kind of Janus droplet containing photoresponsive cholesteric liquid crystals (CLCs) was fabricated for the first time and their formation, compartment structure, mesophase texture and function were thoroughly investigated. In the droplets, the CLC compartments included a typical nematic LC (4'-pentyl-4-biphenylcarbonitrile) doped with an azobenzene-containing chiral dopant, and the other compartments were formed of a poly(dimethylsiloxane)-based oligomer. Janus droplets were fabricated through microphase separation of the incompatible components in chloroform solution dispersed in an aqueous medium, induced by slow evaporation of chloroform. The mesophase structures of the CLC phase in Janus droplets, both suspended in aqueous medium and spreading on substrates, were controlled by the bulk elastic free energy of the CLC phase, surface anchoring and confining geometries. The helix pitch of the cholesteric phase in the droplets was determined by the doping concentration of the chiral dopant. For the suspended Janus droplets with the helix pitch obviously smaller than the droplet sizes, the CLC compartments mainly possessed a bipolar structure instead of the Frank-Pryce structure typically observed on CLC droplets. After the Janus droplets spread on the substrates, the CLC compartments changed to crescent shapes due to the different wettability characteristics of the two compartments, and the formed stable and metastable CLC configurations were distinctively different from those in the suspensions. Interestingly, when the Janus droplets spreading on substrates were irradiated with a laser beam (λ = 488 nm) of low intensity, the directors in the CLC compartments rearranged to form fingerprint structures with minimum total energy.

Textured Electrodes: Manipulating Built-In Crystallographic Heterogeneity of Metal Electrodes via Severe Plastic Deformation.

Control of crystallography of metal electrodeposit films has recently emerged as a key to achieving long operating lifetimes in next-generation batteries. It is reported that the large crystallographic heterogeneity, e.g., broad orientational distribution, that appears characteristic of commercial metal foils, results in rough morphology upon plating/stripping. On this basis, an accumulative roll bonding (ARB) methodology-a severe plastic deformation process-is developed. Zn metal is used as a first example to interrogate the concept. It is demonstrated that the ARB process is highly effective in achieving uniform crystallographic control on macroscopic materials. After the ARB process, the Zn grains exhibit a strong (002) texture (i.e., [002]Zn //ND). The texture transitions from a classical bipolar pattern to a nonclassical unipolar pattern under large nominal strain eliminate the orientational heterogeneity of the foil. The strongly (002)-textured Zn remarkably improves the plating/stripping performance by nearly two orders of magnitude under practical conditions. The performance improvements are readily scaled to achieve pouch-type full batteries that deliver exceptional reversibility. The ARB process can, in principle, be applied to any metal chemistry to achieve similar crystallographic uniformity, provided the appropriate temperature and accumulated strains are employed. This concept is evaluated using commercial Li and Na foils, which, unlike Zn (HCP), are BCC crystals. The simple process for creating strong textures in both hexagonal and cubic metals and illustrating the critical role such built-in crystallography plays underscores opportunities for developing highly reversible thin metal anodes (e.g., hexagonal Zn, Mg, and cubic Li, Na, Ca, Al).

EBSD Characterization of the Microstructure of 7A52 Aluminum Alloy Joints Welded by Friction Stir Welding.

The microstructure and texture of materials significantly influence the mechanical properties and fracture behavior; the effect of microstructure in different zones of friction stir-welded joints of 7A52 aluminum alloy on fracture behavior was investigated in this paper. The microstructural characteristics of sections of the welded joints were tested using the electron backscattered diffraction (EBSD) technique. The results indicate that the fracture is located at the advancing side of the thermomechanically affected zone (AS-TMAZ) and the stir zone (SZ) interface. The AS-TMAZ microstructure is vastly different from the microstructure and texture of other areas. The grain orientation is disordered, and the grain shape is seriously deformed under the action of stirring force. The grain size grows unevenly under the input of friction heat, resulting in a large amount of recrystallization, and there is a significant difference in the Taylor factor between adjacent grains and the AS-TMAZ–SZ interface. On the contrary, there are fine and uniform equiaxed grains in the nugget zone, the microstructure is uniform, and the Taylor factor is small at adjacent grains. Therefore, the uneven transition of microstructure and texture in the AS-TMAZ and the SZ provide conditions for crack initiation, which become the weak point of mechanical properties.

Investigation of microstructure, crystallographic texture, and mechanical behavior of magnesium-based nanocomposite fabricated via multi-pass FSP for biomedical applications

In this work, the microstructure, crystallographic texture, hardness, and tensile behavior of AZ91/HA bio-nano composite manufactured by multi-pass friction stir processing (FSP) were investigated. With increasing the number of FSP passes, the average size of grains is reduced. The processed AZ91 and AZ91/HA nanocomposite after the third pass had the lowest grain size (4.5 and 2.6 μm, respectively). Also, the average grain size of composites was smaller than that of monolithic samples at the same pass number. The results showed that particle distribution in the AZ91/HA nanocomposite is significantly affected by the number of passes. The increment of the pass number led to a more uniform dispersion of HA nanoparticles in the matrix due to more plastic flow of materials. With increasing the pass number to three, the accumulated strain increased to 0.726 (monolithic) and 0.623 (composite) due to repeating mechanical stirring. There was a texture transition ({101‾1} to {0002}) via performing only one pass of FSP. Suppression of grain rotation by HA nanoparticles maintained the intensity of {101‾1} texture as a corrosion-resistant orientation after the third pass. With increasing the pass number of FSP, the hardness and strength of samples increased due to the grain size reduction and the more uniform dispersion of HA powder. The composite sample after the third pass exhibited the highest hardness of 117.0 HV and ultimate tensile strength of 306.6 MPa. The failure mode of processed samples was ductile. There were smaller dimples on the fracture surface of the composite samples due to their lower grain size and also the presence of HA nanoparticles. Considering the obtained results, the nanocomposite after the third pass can be a good load-bearing implant for biomedical applications.

Breaking the topological protection of target skyrmions by the excitation of spin wave modes under microwave magnetic field

Target skyrmions have been attracting intensive attention as the building block of spintronic devices. However, due to the topological protection of these magnetic textures, an extra driving force is needed to realize the transition between different magnetic textures. Herein, we achieve the transition of these magnetic textures with the breaking of topological protection by applying perpendicular microwave magnetic field, which is assisted by the excitation of breathing modes and hybridized modes (combination of breathing modes and radial spin wave modes). Another distinct resonance mode originating from the interaction of hybridized mode and breathing mode is also found, which is excited by isolated annular domain in different positions of nanodisks. Our results provide an insight for the understanding of complex dynamic behaviors in magnetic textures and the designing of spintronics devices.

Offsetting strength-ductility tradeoff in Mg-Sn-Zn-Zr alloy by a novel differential-thermal ECAP process

Equal-channel angular pressing (ECAP) technique is a promising method to enhance the properties of Mg alloys. Herein, a novel differential-thermal ECAP process (DTECAP) with pre-aging treatment (T6) was developed to simultaneously improve strength and ductility of Mg-Sn-Zn-Zr (TZK) alloys. After T6-DTECAP, the TZK alloy exhibited high ultimate tensile strength (UTS) of ~323 MPa and excellent elongation (El.) of ~28.7%, showing superior balance of strength and ductility. Examination microstructures of TZK alloys revealed that the excellent comprehensive properties were mainly associated with the activation of {10–12} tension twin variants and non-basal slips. Moreover, the grain refinement, fine second phases, and transition of strong ED texture to fiber (10–10) < 11–20 > texture along TD were also beneficial for the enhanced properties. This work aims to provide a novel insight for the development of high-performance Mg alloys using T6-DTECAP processing.

Strain rate effects on microstructure and texture evolution in cold-sheared Al-6 Mg alloys during low-temperature annealing

This study examined the effects of the strain rate on the texture evolution of Al-6Mg alloys over one hour of annealing at 300 °C. Three different strain rates of 0.1 s−1, 1 s−1, and 10 s−1 were applied to the samples using a torsion tester. Considerable grain growth was observed in the 0.1 s−1 cold-sheared sample during one hour of annealing. The growth of B/B- and C-oriented grains can explain the grain coarsening behavior. The conventional grain growth, nucleation, and subsequent grain growth, plausibly describe the grain size evolution of those 1 s−1 and 10 s−1 cold-sheared samples during annealing. A textural transition from brass-type to copper-type was evident during the annealing process of the 1 s−1 cold-sheared sample. On the other hand, the brass-type texture bias in the 10 s−1 cold-sheared sample increased gradually over one hour of annealing. The copper-type texture generally evolved under the 0.1 s−1 cold-sheared condition. Generally, the misorientation indices (= M-index) of all three cold-sheared samples were decreased by extending the annealing time. A smaller M-index indicates stronger texture anisotropy. Although the M-index was higher in the 0.1 s−1 and 10 s−1 cold-sheared samples than the 1 s−1 sample throughout the annealing process, the M-index of the 0.1 s−1 sample eventually became the lowest among the three conditions under the fully annealed condition.

Thermally-driven flows and turbulence in vibrated liquids

Within the vast array of variants encompassed by thermal (buoyancy) convection, the particular interest of the present work is on the specific dynamics which are enabled when standard steady gravity is replaced by a time-periodic body force induced by vibrations. The study is designed as a set of separate problems, where each exemplar aims to unravel the implications of the fundamental properties of this type of flow. These include the symmetry of the emerging pattern as perceived by a real observer and as seen in a “time-averaged space”, the synchronous or non-synchronous response of the velocity field to the applied forcing, the magnitude of the so-called Thermofluid-dynamic (TFD) distortions and the peculiar route of evolution towards chaos. A kaleidoscope of previously unknown solutions is reported giving emphasis to some still poorly known aspects such as the complex nature of the textural transitions that take place in the flow as the Gershuni number is increased (from 3.30 × 102 to 5.00 × 107 for Pr = 15). It is shown that the low-frequency regime is relatively stable over this range. In addition to the standard quadrupolar pattern, in such a case peculiar convective structures emerge where the time-averaged rolls display a very regular columnar arrangement, which has been rarely observed in earlier studies. Chaotic states are enabled when larger frequencies of vibration are considered. While for intermediate frequencies concurrent aspects of the Feigenbaum and Manneville and Pomeau mechanisms can be recognized, the hallmark of the high frequency regime is its adherence to the standard Ruelle-Takens scenario.

Microstructure evolution of AZ31B sheet deformed by electric hot temperature-controlled single point incremental forming

Electric hot incremental forming (EHIF) is a flexible sheet forming process based on the Joule heating effect and the accumulation of local plastic deformation to achieve the final shape. This study carried out the EHIF for AZ31B sheet, using an indirectly method of controlling the temperature of the sheet by controlling the temperature of the tool. The truncated pyramid shell with a depth of 25 mm was finally obtained. The microstructure characteristics at different forming zones of the component were analyzed by optical microscope (OM) and electron back scatter diffraction (EBSD) technique. The main reason for the improvement of the formability was attributed to the dynamic recrystallization (DRX) which was affected by the cumulative effect of heat during the tool feeding process. In the early forming zone, due to the weak heat accumulation, the development of DRX was restricted, and twinning and slip played a prominent part in the sheet deformation. Non-basal slip induced the texture transition from {0001} <11–20> to {0001} <10-10> and created conditions for twinning. The twins grew up to coordinate the deformation due to the subsequent deformation and contributed to further unidirectional deflection of the basal texture orientation. The DRX took a leading role in the final forming zone, making the basal texture characteristics inherited but showing a weakening trend.

Effect of traverse and rotational speeds on microstructure, texture, and mechanical properties of friction stir processed AZ91 alloy

In the current work, the influences of both traverse and rotational speeds of friction stir processing (FSP) on the microstructural evolution, crystallographic texture, and mechanical properties of AZ91 alloy were investigated. The tool traverse and rotational speeds used in the present study were 20, 40, 60 mm/min, and 400, 800, 1200 rpm, respectively. The average grain size significantly decreased from 61.6 μm in the as-cast condition to below 10 μm in the FSP-processed samples owing to the occurrence of dynamic recrystallization (DRX). By increasing the tool traverse speed and decreasing the rotational speed, the grain size reduced. The grain boundaries pinned by fine β-Mg17Al12 particles, retarding the grain growth. The fraction of the β-Mg17Al12 remarkably decreased after the FSP owing to fragmentation and dissolution. The high strain rate of the 800–40 and 1200–40 samples coupled with their higher peak temperatures increased the dissolution of β-Mg17Al12 during FSP. It was found that a texture transition from (10.1) pyramidal to (00.2) basal occurred by decreasing the traverse speed and increasing the rotational speed. The highest microhardness, which was equal to 104.4 HV, belongs to the 800–20 sample due to its very fine grains. When the rotational speed increased from 400 to 1200 rpm, the ultimate tensile strength (UTS) improved from 236.8 to 267.1 MPa, the total elongation (TE) decreased from 7.5% to 6.6%, and the energy absorption (EA) improved from 13.1 to 14.2 J/cm3. These results were due to the higher accumulated strain, the larger solid solution strengthening, the lower aspect ratio of β-Mg17Al12, stronger {0002} texture, and the lower content of β-Mg17Al12 of the 1200–400 sample. The UTS and TE of the 1200–40 sample showed an enhancement of 96.4% in UTS, 26.9% in TE, and 132.8% in EA as compared to the as-cast AZ91. Up to the true strain of 0.05, with increasing the rotational speed, the strain hardening rate increased owing to decreasing the fraction of grain boundaries. After the true strain of 0.05, the strain hardening rate reduced by increasing the rotational speed due to strengthening the {0002} texture. The fractured surface of the 800–20 sample had the largest number and smallest size of dimples as compared to the other FSP-processed samples owing to its lowest grain size. Finally, the strong {0002} basal texture in the 800–40, 1200–40, and 800–20 samples led to tear ridges aligning with the normal direction of fractured surfaces.

Toward semantic image inpainting: where global context meets local geometry

Image inpainting attempts to fill the missing areas of an image with plausible content that is visually coherent with the image context. Semantic image inpainting has remained a challenging task even with the emergence of deep learning-based approaches. We propose a deep semantic inpainting model built upon a generative adversarial network and a dense U-Net network. Such a design helps achieve feature reuse while avoiding feature explosion along the upsampling path of the U-Net. The model also uses a composite loss function for the generator network to enforce a joint global and local content consistency constraint. More specifically, our new loss function combines the global reconstruction loss characterizing the semantic similarity between the missing and known image regions with the local total variation loss characterizing the natural transitions among adjacent regions. Experimental results on CelebA-HQ and Paris StreetView datasets have demonstrated encouraging performance when compared with other state-of-the-art methods in terms of both quantitative and qualitative metrics. For the CelebA-HQ dataset, the proposed method can more faithfully infer the semantics of human faces; for the StreetView dataset, our method achieves improved inpainting results in terms of more natural texture transitions, better structural consistency, and enriched textural details.

Insights of texture and microstructure evolution in the short time annealing of Al-Cu-Mg alloy at large temperature range

Texture and microstructure evolution of the 2524 Al-Cu-Mg cold rolled sheet in the annealing at 140–560 °C (for 1 h), was investigated carefully using X-ray diffraction, scanning electron microscopy, and electron backscatter diffraction. The characteristic texture transition rate spectral curve (CTTS), texture index, and orientation streamline approach were utilized to study the successive rules and unknown micro-mechanisms. The results demonstrated that the CTTS could precisely obtain the rule, tendency, and abnormal region of texture evolution within a large temperature range. An abnormal valley zone of texture evolution was observed at 380–440 °C, which is related to the rotation of Cube texture, and huge pinning force from the second phase. The orientation streamline approach effectively revealed the potential evolutional mechanisms of the texture, including α55° {φ1 = 55°, φ = 45°, φ2 = 0°}, Cu35° {φ1 = 35°, φ = 90°, φ2 = 45°}, and F {φ1 = 90°, φ = 55°, φ2 = 45°}. The content of ∑3 twin grain boundary and texture index FCGB weaken each other in the temperature ranges of 320–400 °C and 440–560 °C.

Prediction of Axillary Lymph Node Metastasis in Breast Cancer using Intra-peritumoral Textural Transition Analysis based on Dynamic Contrast-enhanced Magnetic Resonance Imaging

Intra-peritumoural textural transition (Ipris) is a new radiomics method, which includes a series of quantitative measurements of the image features that represent the differences between the inside and outside of the tumour. This study aimed to explore the feasibility of Ipris analysis for the preoperative prediction of axillary lymph node (ALN) status in patients with breast cancer based on dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). This study was approved by the Institutional Review Board (IRB) of our hospital. One hundred sixty-six patients with clinicopathologically confirmed invasive breast cancer and ALN status were enrolled. All patients underwent preoperative breast DCE-MRI examinations. The primary breast lesion was manually segmented using the ITK-SNAP software for each patient. Two sets of image features were extracted, including Ipris features and conventional intratumoural features. Feature selection was conducted using Spearman correlation analysis and support vector machine with recursive feature elimination (SVM-RFE). Next, three models were established in training dataset: Model 1 was established by Ipris features; Model 2 was established by intratumoural features; Model 3 was established by combining Ipris features and intratumoural features. The performances of the three models were evaluated for the prediction of ALN status in testing datasets. Model 1 with four Ipris features achieved an AUC of 0.816 (95% CI, 0.733-0.883) and 0.829 (95% CI, 0.695-0.922) in the training and testing datasets, respectively. Model 2 with six intratumoural features achieved an AUC of 0.801 (95% CI, 0.716-0.870) and 0.824 (95% CI, 0.689-0.918) in the training and testing datasets, respectively. By incorporating the Ipris and intratumoural features, the AUC of Model 3 increased to 0.968 (95% CI, 0.916-0.992) and 0.855 (95% CI, 0.724-0.939) in the training and testing datasets, respectively. Ipris features based on DCE-MRI can be used to predict ALN status in patients with breast cancer. The model combining intratumoural and Ipris features achieved higher prediction performance.

Texture and mechanical properties of Cu alloy by cryogenic high-speed rolling

Cryogenic high-speed rolling (CHSR), where the sheet cooled in liquid nitrogen is supplied to rolls rotating at 1500 m/min at room temperature, was applied to several Cu alloys. After the CHSR, mechanical strength was improved with texture transition from the ‘copper-type’ to the ‘brass-type’ components. This trend was clearly observed in the case of Cu alloys with intermediate SFE. It is considered that the deformation mode changed from the dislocation slip to deformation twinning and shear banding under high Z parameter conditions of CHSR. It is also found that CHSR can improve the strength of Cu alloys with less decrease in electrical conductivity.

Effects of salinity, organic acids and alkalinity on the growth of calcite spherulites: Implications for evaporitic lacustrine sedimentation

AbstractLacustrine non‐skeletal carbonates exhibit a diversity of petrographies due to interactions between physico‐chemical and biologically influenced mechanisms. Despite the suggestion that evaporative concentration was involved in the formation of spherulite and shrubby‐bearing carbonate successions in the Pre‐Salt Cretaceous alkaline lakes of the South Atlantic, no consensus exists about the water chemistries promoting these exotic mineral textures. In this work, an experimental approach was developed to evaluate how changes in salinity (NaCl) and biopolymer concentrations (alginic acid) impact calcite growth dynamics from saline and alkaline synthetic solutions. Hydrochemical and petrographical data from selected modern saline/alkaline environments were compared with experimental datasets to further estimate how the underlying (bio)chemical conditions and lake locations probably converge to allow the formation of calcite spherulite grains in evaporitic settings. Spherulitic calcite from Recent saline lakes and experiments arise from waters with moderate to high [Calcium]/[Alkalinity] ratios ([Ca]/[Alk]) rather than in calcium‐depleted and alkaline‐rich environments which tend to produce single‐crystal calcites during abiotic water mixing or lake evaporation. This observation is consistent with the assembly of polycrystalline textures being a kinetically controlled feature, forced by remarkably high rates of nucleation. Also, the data analysed do not support a causative relationship between evaporite‐driven salinity fluctuations and the preferential formation of spherulites, shrubs or their intermediate textures. Ubiquitous in saline lakes, organic substances can lower the kinetic thresholds for spherulitic calcite aggregation while microbial photosynthesis can also raise pH, altogether enhancing calcite supersaturation and promoting spherulite formation in waters with moderate‐high [Ca]/[Alk] ratios and high salinities. Localised observations of abiotic spherulites in Recent soda lakes can occur in restricted mixing zones where [Ca]/[Alk] ratios are enhanced. This work highlights the roles of concentration regimes associated with biopolymers and microbial metabolism against the background salinity fluctuations in determining the morphological and textural transitions in lacustrine carbonate minerals.

Texture Selection Mechanisms during Recrystallization and Grain Growth of a Magnesium-Erbium-Zinc Alloy

Binary and ternary Mg-1%Er/Mg-1%Er-1%Zn alloys were rolled and subsequently subjected to various heat treatments to study texture selection during recrystallization and following grain growth. The results revealed favorable texture alterations in both alloys and the formation of a unique ±40° transvers direction (TD) recrystallization texture in the ternary alloy. While the binary alloy underwent a continuous alteration of its texture and grain size throughout recrystallization and grain growth, the ternary alloy showed a rapid rolling (RD) to transvers direction (TD) texture transition occurring during early stages of recrystallization. Targeted electron back scatter diffraction (EBSD) analysis of the recrystallized fraction unraveled a selective growth behavior of recrystallization nuclei with TD tilted orientations that is likely attributed to solute drag effect on the mobility of specific grain boundaries. Mg-1%Er-1%Zn additionally exhibited a stunning microstructural stability during grain growth annealing. This was attributed to a fine dispersion of dense nanosized particles in the matrix that impeded grain growth by Zener drag. The mechanical properties of both alloys were determined by uniaxial tensile tests combined with EBSD assisted slip trace analysis at 5% tensile strain to investigate non-basal slip behavior. Owing to synergic alloying effects on solid solution strengthening and slip activation, as well as precipitation hardening, the ternary Mg-1%Er-1%Zn alloy demonstrated a remarkable enhancement in the yield strength, strain hardening capability, and failure ductility, compared with the Mg-1%Er alloy.

Synthesis and Diagnosis New Metallotropic LCs from Organotin (IV) Complex

Organotin (IV) complex is part of the organometallic chemistry and in recently decades have a variety of interesting and application used it. A new class of metallomesogens LC (A) Ph3Sn(VAL), (B) Bu3Sn(VAL), (C) Ph2Sn(VAL)2 and (D) Bu2Sn(VAL)2 was synthesis through the reaction of valsartan ligand with (di- or tri- butyl tin chloride salt) and (di- or tri- phenyl tin chloride salt) in methanol solvent. 1H NMR,119 Sn NMR, FTIR and CHN elemental analyses were measure and the liquid crystalline properties were study by POM. The mesophase in all organotin (IV) carboxylate complexes are thermotropic nematic phase. In complexes (A, C) the optical textures of A show a typical droplet texture and thread shape LC phase transition between (400-440⁰C) higher than mesophase textures in C between (230 -250⁰C). In complexes (B, D) the optical textures of B appearance a thread shape and the LC phase transition temperature between (200 -400⁰C) and in D thread shape and the transition temperature beginning up to 280⁰C. From a temperature of phase transition show that the complexes (C, D) are start liquid crystal mesophase in lower than complex (A, C) because effect of R-group and types which due to an asymmetric arrangement of the molecule and a geometry was calamitic in which the length of the molecule is major in compare with its diameter.