Formation Of Lamellar Structure Research Articles

Effect of electric mode of micro-arc oxidation on structural and phase state of calcium-phosphate coating

The micro-arc oxidation method has been used to obtain calcium-phosphate coatings on titanium surface, expected to have bioactive properties. The effect of the pulse current duty cycle and voltage of micro-arc oxidation on the morphology, elemental and phase composition of the coating has been studied. Decrease in the pulse duty cycle during micro-arc oxidation results in the formation of flake, spheroidal and lamellar structures. It has been shown that the Ca/P ratio and surface roughness of the coating increases regardless of the pulse duty cycle with increase of applied voltage. Depending on the application mode, the Ca/P ratio and the roughness of calcium phosphate coatings ranged from 0.44 to 0.67 and from 4.2 to 6.8 μm, respectively. It was found that change of the pulse current duty cycle and increase of the voltage up to 600 V results in the formation of the main crystalline phases Ca(H2PO4)2(H2O) and CaPO3(OH) in the coatings.

Effect of Heat Input on Austenite Reversion, Recrystallization, and Ensuing Impact Toughness in Simulated Intercritical Coarse‐Grained Heat Affected Zone of Medium Mn Steel

A systematic experimental study has been conducted on the simulated intercritical coarse‐grained heat affected zone of 690 MPa grade heavy‐plate medium Mn steel by tailoring heat input of the first welding pass to obtain the influence of initial microstructure on the austenite reversion mechanism, recrystallization, and resultant impact toughness. Results reveal that prior austenite grain size significantly increases from 30 ± 11, 41 ± 14 to 54 ± 15 μm with the increasing heat input from 15, 30 to 50 kJ cm−1, which affect the nucleation site of reversed austenite, recrystallization mechanism, and final microstructure. Accordingly, impact toughness is better at the heat input of 30 kJ cm−1 (75.2 ± 0.8 J) in comparison with that of 15 kJ cm−1 (63.3 ± 13.3 J) and 50 kJ cm−1 (26.7 ± 6.5 J) at −40 °C, which is mainly ascribed to the formation of lamellar heterogeneous structures, multiplication of slip system and morphology of high‐angle grain boundaries.

Mulberry (Morus alba L.) leaf powder modified the processing of meat alternatives: Principal component analysis from apparent properties to chemical bonds

For texture control in plant-meat alternatives, the interrelationship between apparent characteristics and chemical bonds in high-fiber formulations remains unclear. The influence of mulberry leaf powder on apparent characteristics and chemical bonds of raw materials, block and strip products at addition amounts of 0.5–25% was analyzed. The results showed that 8% addition significantly increased the chewiness of the block by 98.12%. The strips' texture shows a downward trend, and the processing produced more redness and color difference. Additives promoted the formation of voids, lamellar and filamentous structures, and the strip produced more striped structures. Disulfide bonds significantly increased in the block, and the β-turn in the secondary structure enhanced by 12.20%. The β-turn transformed into a β-sheet in strips. Principal component analysis revealed that the texture improvement was associated with producing disulfide bonds and β-turn, providing a basis for high-fiber components to improve products' apparent characteristics by chemical bonds.

Evading strength-ductility trade-off dilemma in TRIP-assisted Fe50Mn30Co10Cr10 duplex high-entropy alloys via flash annealing and deep cryogenic treatments

Conventional and multi-component alloys frequently compromise ductility to strike a balance between strength and ductility through intricate thermomechanical processes. Hence, it is essential to explore a straightforward and efficient approach to concurrently attain high strength and ductility. In this work, an ultrafast annealing-deep cryogenic treatment-tempering (UHDCT) method is proposed to significantly improve the mechanical properties of Fe50Mn30Co10Cr10 duplex high-entropy alloy (HEA). The UHDCT method leads to a substantial ∼58 % increase in strength and a remarkable ∼96 % increase in elongation, which are comparable to the outcomes achieved through complex thermomechanical treatments. After UHDCT treatment, a hierarchical heterogeneous structure is achieved, which is comprised of an ultrafine surface region, a transitional region, and an interior region. The deep cryogenic treatment applied to the intermediate link induces the formation of nano-scale needle-like martensitic variants that, instead of transforming back to austenite, undergo coarsening due to their high thermal stability. This coarsening process triggers the formation of lamellar structures in the surface regions. As a result, twinning-induced plasticity (TWIP) mainly governs the plastic deformation of the surface regions, thereby enhancing strength. Furthermore, progressive austenite recovery results in an increased volume fraction and refined grain size, further contributing to the strength and ductility via the transformation-induced plasticity (TRIP) effect. The present findings provide a convenient pathway for introducing hierarchical heterogeneous structures in TRIP-type HEAs, thereby expanding design possibilities for creating high-performance HEAs.

Synergistic effects of dry-brush compatibility and shear stress on rapid alignment of lamellar microstructures for block copolymer reflectors

Because of the high viscosity of severe chain entanglements, a time-consuming process of aligning microstructural orientation in high molecular-weight (Mw) block copolymer photonic crystal films imposed limitations on efficient mass production. In this study, the effective alignment of the block copolymer microstructures in the film state can be carried out within approximately a few minutes. This achievement was realized through the synergistic localized compatibility of dry brush and shear stress during the spin-casting process. The orientation and orderliness of the microphase-separated lamellar structure in as-spun poly(styrene)-block-poly(4-vinylpyridine) (PS-b-P4VP) films can be meticulously controlled by introducing blends with PS homopolymer (hPS) of varying Mws (Mw,hPS) and cholesteric liquid crystal mesogen (Chol). Within the ternary blended films of hPS/PS-b-P4VP(Chol), the wet-brush miscibility by blending low-Mw hPS with a small molecular weight ratio (α) of Mw,hPS to Mw,bPS (Mw of the PS block chain) of α <1 results in the formation of disoriented lamellar structures, whereas dry-brush localization by introducing high-Mw hPS with α∼0.9 yields highly parallel-aligned lamellar structures to the substrate after spin casting, even with a massive quantity of additive hPS (∼59 wt%). The dry-brush compatibility can be demonstrated by morphological observation in the ternary blended film after extraction of the hPS. As a result, without any further efforts, such as additional solvent or thermal annealing treatments, the as-spun ternary blended film can exhibit visible structural colorations with controlled wavelengths by alternating the quantity of hPS. This provides an accessible solution for rapidly producing flexible photonic crystals featuring tunable photonic band gaps.

Delamination Fracture in a Medium-Carbon Low-Alloy Steel Subjected to Tempforming

The effect of tempforming on strength and fracture toughness of a 0.4%C-2%Si-1%Cr- 1%Mo-VNb steel was examined. Tempering at a temperature of 600°C followed by plate rolling at the same temperature results in the formation of lamellar structure with a spacing of 72 nm between longitudinal boundaries and a lattice dislocation density of ~1015 m−2 that enhances fracture toughness in normal direction of tempformed plate. The increase in the absorbed impact energy is attributed to delamination, which occurs in plains intersecting the propagation path of main crack that blunts crack tip.

Mixing intensification in an acoustofluidic micromixer aided with micro-pillars

In this work, we present an acoustofluidic micromixer that employs the combination of acoustic waves and micro-pillars to achieve enhanced mixing performance. We have shown that micro-pillars can generate micro-vortices, which lead to intense stretching and folding of the fluid trapped inside the micromixer and subsequently result in the formation of lamellar structures consisting of layers of the stretched fluids having steep concentration gradients between them. High concentration gradients coupled with the increased interfacial area result in higher rates of molecular diffusion. A numerical study is conducted, testing the performance of micro-pillars of three different designs in comparison to a simple rectangular acoustofluidic micromixer without any micro-pillars. The performance of the device in terms of improving the reaction kinetics of a chemical process has also been analyzed. For wide aspect ratio microchannels, our acoustofluidic micromixer helps in achieving rapid and homogeneous mixing while maintaining a high throughput.

Impact of rolling temperature on the deformation structure and mechanical performance of a CrMnFeCoNi high-entropy alloy

The impact of warm-rolling at 773 K to 76% and 90% thickness reduction on the microstructure and mechanical properties of an equiatomic CrMnFeCoNi high entropy alloy is compared to material that is cold-rolled and subsequently annealed between 673 and 1173 K. While cold-rolling significantly improves hardness and yield strength, subsequent annealing with increasing temperature improves ductility due to stress-relaxation, recovery, and recrystallization of the elongated grain structure which simultaneously reduces hardness and strength. Compared to the cold-rolled condition, however, annealing at 773 K increases hardness and strength as well as ductility which may be associated with the onset of chemical ordering combined with a lack of the formation of precipitates. Warm-rolling at 773 K, on the other hand, results in partially recrystallized microstructures without mechanical nanotwins. While the 76% deformed material exhibits mechanical properties that are comparable to the cold-rolled and annealed materials, the 90% warm-rolled material shows significantly improved hardness compared to the cold-rolled material, similar strength, but improved plastic failure strains. These properties are associated with the formation of a fine lamellar deformation structure and the onset of the precipitation of Cr-rich particles during rolling. Our results reveal that warm-rolling may enable an efficient pathway to obtain structure-property relationships in HEAs that can otherwise only be obtained in a multi-step processing procedure.

Strong cooperation growth of two phases in the ternary eutectic

The growth mechanism and tensile performance of ternary Ni40.6Fe36.4Ti23 alloy were investigated using directional solidification technique. The ternary Fe2Ti+γ-Fe(Ni)+Ni3Ti eutectic formed a lamellar structure under the steady state growth. After quenching, the Fe2Ti phase transformed into independently grown fiber while the γ-Fe(Ni) and Ni3Ti phases kept lamellar structure. It was confirmed that the solid/solid interfacial energy anisotropy contributed to the strong cooperation growth of the two phases in the ternary eutectic. The γ-Fe(Ni)/Ni3Ti interface preferred to be parallel to the common planes of {111}γ and {0001}Ni3Ti with low interfacial energy, leading to the formation of the stable lamellar structure under different solidification conditions. Owing to the reduction of transverse grain boundaries and grain refinement, the alloy solidified at 10 μm/s growth velocity showed the highest tensile strength and Young's modulus with translamellar fracture mechanism.

Electrochromic composites films composed of MoO3 doped by tungsten atoms with remarkable response speed and color rendering efficiency via electrochemical deposition

Molybdenum oxide (MoO3) stands out as a predominant electrochromic material, finding extensive applications in sustainable photoelectric devices such as multifunctional smart windows. This study introduces an innovative approach to fabricating electrochromic composite films by doping molybdenum oxide with tungsten atoms through electrochemical deposition on indium tin oxide (ITO) substrates. Electrochemical and optical measurements demonstrate the films' superior performance in terms of switching time and coloring efficiency. Analyses using X-ray photoelectron spectroscopy and transmission electron microscopy suggest the formation of a distinct lamellar structure during the electrodeposition process. Additionally, the incorporation of tungsten atoms appears to facilitate an effective WOMo bonding connection. This introduction of W atoms may create a new doping energy level. The unique lamellar structure enhances the number of electrochemically active sites, while the WOMo coupling acts as a channel for electron migration. Consequently, the switching time decreased from 5.5 s to 3.9 s, and the coloring efficiency increased from 15.47 cm2 C−1 to 40.43 cm2 C−1. Furthermore, the transmittance of the W-doped MoO3 films surpasses that of the pure MoO3 films. Overall, tungsten doping improves the electrochromic properties of MoO3, indicating promising potential for further applications.

Enhancing the strength and conductivity of commercialized Cu-Cr-Zr plate through simple high strain cold rolling and aging

Plastic deformation usually improves the strength of Cu alloys by introducing high density dislocations and refined grains, but inevitably reducing electrical conductivity and ductility. Here we demonstrate that three exclusive properties, i.e., strength, conductivity, and ductility can be simultaneously enhanced in commercialized Cu-Cr-Zr plates through the well-controlled thermomechanical treatment. Very high strain cold rolling with a thickness reduction of 98% is applied, resulting in the formation of ultra-fine lamellar structures with an average size of 146 nm, which contributes to high tensile strength of 643 MPa. However, the elongation and electrical properties are poor. The subsequent aging treatment at a low temperature of 400 °C for 5 h introduces high density coherent Cr precipitates in those lamellar structures, while keeping the lamellar thickness almost unchanged. The aged Cu-Cr-Zr alloy exhibit high strength of 592 MPa, high conductivity of 86.8% IACS, and adequate elongation of 15.5%. This work proposes a strategy of overcoming the strength-ductility and strength-conductivity trade-off relationships in industrial Cu products through the balanced manipulation of grain morphology and grain interior precipitation.

Tailoring strength and ductility of Mg97Y2Zn1 alloy through the architecture of heterogeneous lamellar structure by large-ratio hot extrusion

In this study, a heterogeneous lamellar structure is achieved in Mg97Y2Zn1 alloy via large-ratio hot extrusion of the alloys in as-cast (CE) and as-annealed (AE) stages. The ultimate tensile strength (UTS) of CE and AE alloys is 426.5 and 471.4 MPa, and their fracture elongation (FE) is 8.1% and 1.0%, respectively. Mechanical properties of the CE and AE alloys exceed that of the majority of wrought Mg97Y2Zn1 alloys due to the heterostructure induced strengthening. Both in the two extruded alloys, α-Mg layers and LPSO layers acting as soft and hard domains, respectively, constitute the heterogeneous lamellar structure. As a result of the narrower spacing of α-Mg and LPSO layers, more refined DRX grains and LPSO particles, and the increased volume fraction of LPSO phase, the strength of the AE alloy is higher than that of CE alloy. However, the AE alloy exhibits poor ductility owing to the easy aggregation of dislocations and stress at the interfaces of narrower layers. Based on discussion of the strengthening mechanisms, the preparation of Mg97Y2Zn1 alloys with tailored mechanical properties of high UTS ranging from 420 to 480 MPa, and FE 1~ 8%, could be realized via the combination of annealing (controlling the content of 14H phase) and large-ratio hot extrusion (promoting the formation of heterogeneous lamellar structure).

Dislocation mechanisms in strengthening and softening of nanotwinned materials

Twin boundary (TB) strengthening in nanotwinned metals experiences a breakdown below a critical spacing at which softening takes over. Here, we survey a range of nanotwinned materials that possess different stacking fault energies (SFEs) and understand the TB strengthening limit using atomistic simulations. Distinct from Cu and Al, the nanotwinned, ultralow SFE materials (Co, NiCoCr, and NiCoCrFeMn) intriguingly exhibit a continuous strengthening down to a twin thickness of 0.63 nm. Examining dislocation slip mode and deformation microstructure, we find the hard dislocation modes persist even when reducing the twin boundary spacing to a nanometer regime. Meanwhile, the soft dislocation mode, which causes detwinning in Cu and Al, results in phase transformation and lamellar structure formation in Co, NiCoCr, and NiCoCrFeMn. This study, providing an enhanced understanding of dislocation mechanism in nanotwinned materials, demonstrates the potential for controlling mechanical behavior and ultimate strength with broadly tunable composition and SFE, especially in multi-principal element alloys.

The role of pH solution in depositing MoO3 film by spray pyrolysis as hole selective contact on silicon-based heterojunction devices

The thermal evaporation technique has been frequently used for the deposition of sub-stoichiometric molybdenum oxide (MoO3) films. This approach requires a high temperature, which limits the control of MoO3 stoichiometry and affects its conducting mechanism. In this study, a spray pyrolysis technique (SPT) has been used to grow MoO3 film by varying the pH solution. The formation of an orthorhombic lamellar crystal structure with (0 k0) preferred orientation was realized using X-ray diffraction analysis. FESEM analysis confirmed pH solution dependence on the particle growth properties. The vibrational peaks of the Raman spectra justified the presence of the sub-stochiometric α-MoO3 film. The p-n heterojunction diodes constructed based on the Ag/MoO3/n-Si/Al showed a well-defined rectifying behaviour with the film deposited at 0.6 pH solution.

Modification of liposomes composed of a cationic lipid TMAG and an anionic lipid DSPG with a PEGylated lipid based on the investigation of lipid structures

Charged lipids are widely utilized in functional liposomes for controlled release and targeting of drugs. In this study, we prepared the liposomes composed of a cationic lipid N-(α-trimethylammonioacetyl)-distearoyl-D-glutamate chloride (TMAG) and an anionic lipid 1,2-dioctadecanoyl-sn-glycero-3-phospho-1′-rac-glycerol (DSPG) with the molar ratio of TMAG/DSPG = 0:10–10:0 by hydration and extrusion methods. SAXS study for the lipid thin films revealed the formation of lamellar structures of TMAG and DSPG. The lipid thin film, except for the composition of 5:5 and 6:4, formed a liposome with a size of ∼100 nm that could encapsulate riboflavin in the inner aqueous phase. The zeta potentials of liposomes with the composition of 0:10–4:6 showed negative charges, while those of 7:3–10:0 showed positive charges. As the composition approached from 0:10 or 10:0 to 5:5, the phase transition temperature of the lipid bilayer from liquid crystalline phase to gel phase became higher, and the extent of fluorescence anisotropy increased. Thus, the lipid bilayer around the equimolar mixture could form a rigid structure with low fluidity of lipid alkyl chains. The surface charge cancellation by the opposite ionic head groups and the less curvature of the rigid lipid bilayer should prevent the liposomal formation at the composition of 5:5 and 6:4. However, the equimolar composition of 5:5 could form a liposome by the modification of distearoylphosphatidylethanolamine-polyethyleneglycol 2000 (DSPE-PEG2000) into the lipid bilayer at the molar ratio of 4% because it can reduce the rigidity of the lipid bilayer, provide positive curvature to the lipid bilayer, and stabilize the liposome dispersion in water through steric hindrance.

High-rate soft carbon anode in potassium ion batteries: The role of chemical structures of pitches

Soft carbons (SCs) have become a promising anode for potassium ion batteries (PIBs). However, it is challenging to maintain high capacity and long cycle life at rapid charge/discharge rate due to the sluggish insertion/deinsertion of K+. To solve this problem, the morphology of the SCs was regulated by using pitches with different chemical structures. The results showed that the chemical structure of the pitch characterized by less long aliphatic chains led to the largest average distance between polycyclic aromatic nuclei, which caused mild condensation of polycyclic aromatic nuclei and thus the formation of lamellar structures. Abundant short chains of the pitch ignited violent cyclization and aromatization and the shortened average distance, inducing violent condensation to generate the bulk structures. The cyclopenta-fused rings and aromatic methyl groups of the pitch minimized the average distance, which also built the bulk structures. More exposed defect-edge sites and larger active surface of the lamellar SC contributed to the adsorption of K+ and improved reaction kinetics. When the current density increased to 3C,bulk structures did not work while the lamellar still remained high reversible capacity of 160.9 mAh g−1 after 1000 cycles. These findings paved a new way for the design of SCs at the molecular level to satisfy high electrochemical performance at high charge/discharge rate.

Effect of polyols on membrane structures of liposomes: A study using small-angle X-ray scattering data and generalized indirect Fourier transformation

This study aimed to evaluate the membrane structure of distearoylphosphatidylcholine (DSPC) liposomes dispersed in water containing various types of polyols with low molecular weight such as glycerin (Gly), 1,3-butandiol (BG), and propylene glycol (PG). To clarify the detailed membrane structure, generalized indirect Fourier transformation (GIFT) analysis, which provides information about the bilayer spacing, bilayer thickness, number of lamellar layers, and membrane flexibility, was applied to small-angle X-ray scattering (SAXS) data of the present system. The GIFT results showed that the bilayer thickness of the DSPC liposomes followed the order Gly>>BG>PG. In addition, the membrane flexibility estimated by the Caille parameter was in the order Gly>>BG>PG; this result was supported by the gel-liquid crystal phase transition temperature (Tc) obtained by differential scanning calorimetry (DSC). These results, together with the Raman spectra, suggest that BG and PG incorporated into the bilayers of DSPC liposomes result in the formation of an interdigitated lamellar structure.

PNPLA1-Mediated Acylceramide Biosynthesis and Autosomal Recessive Congenital Ichthyosis.

The stratum corneum of the epidermis acts as a life-sustaining permeability barrier. Unique heterogeneous ceramides, especially ω-O-acylceramides, are key components for the formation of stable lamellar membrane structures in the stratum corneum and are essential for a vital epidermal permeability barrier. Several enzymes involved in acylceramide synthesis have been demonstrated to be associated with ichthyosis. The function of patatin-like phospholipase domain-containing protein 1 (PNPLA1) was a mystery until the finding that PNPLA1 gene mutations were involved in autosomal-recessive congenital ichthyosis (ARCI) patients, both humans and dogs. PNPLA1 plays an essential role in the biosynthesis of acylceramide as a CoA-independent transacylase. PNPLA1 gene mutations cause decreased acylceramide levels and impaired skin barrier function. More and more mutations in PNPLA1 genes have been identified in recent years. Herein, we describe the structural and functional specificity of PNPLA1, highlight its critical roles in acylceramide synthesis and skin barrier maintenance, and summarize the PNPLA1 mutations currently identified in ARCI patients.

Structure of a subnanometer-sized semiconductor Cd14Se13 cluster

Structure of a subnanometer-sized semiconductor Cd14Se13 cluster

Formation of hypoeutectic structure and strengthening mechanism of Co4Cr1.5Fe1.5Ni5 high entropy alloy alloyed by Al

To reveal the phase formation mechanism and the strengthening mechanism, the AlxCo4Cr1.5Fe1.5Ni5 alloys (x = 1.0, 1.2, 1.4, 1.6, 1.8, 2.0) were prepared by arc melting. Phase formation and prediction, tensile properties, strengthening mechanism and deformation mechanism were researched in detail. Results show that the microstructure of AlxCo4Cr1.5Fe1.5Ni5 alloys changes from single FCC phases (x ≤ 1.4)) to FCC and BCC phases (x＞1.4), which was in good agreement with the calculated phase diagram (CALPHAD) prediction. The lower mixing enthalpy of Ni-Al leads to the segregation of Al element at the inter-dendritic region, which promotes the formation of BCC and FCC lamellar structure in hypoeutectic Al2Co4Cr1.5Fe1.5Ni5 alloy. The ultimate tensile strength of Al2Co4Cr1.5Fe1.5Ni5 alloy is 835 MPa, meanwhile the fracture strain is 31.8 %. The tensile strength of Al2Co4Cr1.5Fe1.5Ni5 alloy is attributed to the interface strengthening and the solid solution strengthening. The massive cross slip of dislocations in primary FCC phases and the dense dislocations blocked by the FCC-BCC interface increase the tensile strength. The interface barrier strength of the BCC-FCC interface in Al2Co4Cr1.5Fe1.5Ni5 alloy was estimated to be 3.9 GPa, which shows the higher barrier strength than conventional BCC-FCC interfaces. Coupled effects of the primary FCC and the lamellar structure of FCC and BCC phases will maintain good mechanical properties.