Morphology Segregation Research Articles

Study of Effects of Post-Weld Heat Treatment Time on Corrosion Behavior and Manufacturing Processes of Super Duplex Stainless SAF 2507 for Advanced Li-Ion Battery Cases.

Lithium-ion batteries are superior energy storage devices that are widely utilized in various fields, from electric cars to small portable electric devices. However, their susceptibility to thermal runaway necessitates improvements in battery case materials to improve their safety. This study used electrochemical analyses, including open-circuit potential (OCP), potentiodynamic polarization, and critical pitting temperature (CPT) analyses, to investigate the corrosion resistance of super duplex stainless steel (SAF 2507) applied to battery cases in relation to post-weld heat treatment (PWHT) time. The microstructure during the manufacture, laser welding, and PWHT was analyzed using field-emission scanning electron microscopy, X-ray diffraction, and electron backscatter diffraction, and the chemical composition was analyzed using dispersive X-ray spectroscopy and electron probe micro-analysis. The PWHT increased the volume fraction of austenite from 5% to 50% over 3 min at 1200 °C; this increased the OCP from -0.21 V to +0.03 V, and increased the CPT from 56 °C to 73 °C. The PWHT effectively improved the corrosion resistance, laying the groundwork for utilizing SAF 2507 in battery case materials. But the alloy segregation and heterogeneous grain morphology after PWHT needs improvement.

Architected flexible syntactic foams: Additive manufacturing and reinforcing particle driven matrix segregation

Polymer syntactic foams are transforming materials that will shape the future of next-generation aerospace and marine structures. When manufactured using traditional processes, like compression molding, syntactic foams consist of a solid continuous polymer matrix reinforced with stiff hollow particles. However, polymer matrix segregation can be achieved during the selective laser sintering process with thermoplastic polyurethane (TPU). It is uncertain what role hollow particles play in forming this matrix segregation and its impact on the corresponding mechanical properties of syntactic foams. We show that the size of the hollow particles controls the internal microscale morphology of matrix segregation, leading to counter-intuitive macroscale mechanical responses. Particles with diameters greater than the gaps between the cell walls of the segregated matrix get lodged between and in the walls, bridging the gaps in the segregated matrix and increasing the stiffness of syntactic foams. In contrast, particles with smaller diameters with higher particle crushing strength get lodged only inside the cell walls of the segregated matrix, resulting in higher densification stresses (energy absorption). We show that stiffness and densification can be tuned while enabling lightweight syntactic foams. These novel discoveries will aid in facilitating functional and lightweight syntactic foams for cores in sandwich structures.

Usage of the Cast Iron Cylindrical Liner in an Automobile Engine Block

This study addresses the issues related to the quality of the connection between cast iron liners and inserts in a pressure die-cast automotive engine block, along with the macro and micro wear of the cylinder bearing surface. it was found that the commonly used HPDC high-pressure casting technology of Al-Si alloy engine blocks with cast iron liners, in which the cylinder liner is then recreated, does not ensure their metallic connection. The micro-gap created there becomes thicker as the engine is used, which worsens the conditions for heat dissipation from the sleeve to the block. Locally, on the surface of the cylinder bearing surface, reductions in honing effects and longitudinal cracks were observed. The presented literature mechanism of micro wear of the cylinder bearing surface, dependent on the morphology of graphite segregations, was confirmed. The mechanism of creating micro-breaks in the area of phosphoric eutectic and graphite precipitation occurrence was presented, initiated by the formation of microcracks in the eutectic and delaminations at the eutectic-matrix boundary.

Controlling macroscopic segregation of the directed energy deposited Cu–Fe alloy by laser oscillation

To achieve macro-segregation control and obtain a finer grain structure, oscillating laser directed energy deposition (OL-DED) was applied for the first time in the manufacturing of Cu–Fe immiscible alloys. Compared to the L-DED process, the oscillating laser did not affect the microscopic components, but it could regulate the segregation morphology. As the oscillation frequency (f) increases, the morphology of the γ-Fe segregated phase gradually transformed from "crescent" to "column" and discrete "bulk". Moreover, the oscillating laser helped to reduce the grain size of each phase in the Cu–Fe alloy. When f increased to 200 Hz, the grain size of the Cu and Fe phases reached their minimum values, measuring 4.4 μm and 7.2 μm, respectively, which represented reductions of 52.2% and 66.7% compared to the absence of oscillation. Furthermore, at 300 Hz, the segregation morphology transforms into discrete "block-like" structures with higher thermal resistivity and heat accumulation, leading to grain coarsening. Due to the grain refinement effect induced by the oscillating laser, the OL-DED fabricated Cu–Fe alloy exhibited superior tensile properties compared to the L-DED samples, achieving the highest yield strength and tensile strength at 200 Hz, measuring 345 MPa and 418 MPa, respectively. Finally, the study successfully established a correlation between the melt flow state and the macro-segregation morphology of the Fe phase based on the Reynolds model derived from the melt stirring theory, and the evolution mechanism of the grain structure was discussed based on the solidification theory.

Discussion of the Segregation and Low Hardness of Large-Diameter M3 High-Speed Steel Produced by Spray Forming.

As an advanced near-net-shape processing method in which directly preformed, semi-finished products are created from liquid metals, spray forming has become popular in the development and application of new materials and is supporting industrialization. However, as investigated in this work, the problems of segregation and low hardness exist in the actual industrialization process, particularly for large-diameter M3 high-speed steel. It was here found that the annual ring segregation morphologies were mostly distributed from the edge to 1/2R, with a large number of stripes primarily enriched in C, Mo, and Cr elements, and the degree of segregation was mild. The ring segregation was located at the 1/2R position, where the main elemental enrichments were C, W, Mo, Cr, and V, and the segregation degree was severe. The formation of segregation during deposition is described based on an equilibrium solidification model. A slow cooling rate and heat dissipation from the surface to the inside were judged to be the main factors causing segregation and changes in the carbide morphology. In terms of hardness, with the increase in the quenching temperature to 1230 °C, the tempering hardness increased significantly. The analysis shows that a faster cooling rate in the atomization stage caused the solidified droplets to exhibit rapid solidification characteristics, and there was a higher proportion of MC carbide in the deposited billet. MC carbides cannot be fully dissolved using the conventional heat treatment process, which decreases the C, Cr, Mo, and V contents in the solution and, thus, reduces the secondary hardening capability. The findings show that, when the spray forming process is used to prepare large-diameter materials, it should not be considered a rapid solidification technology simply because of its atomization stage. Moreover, more attention should be paid to the influence of microstructure transformation during atomization and deposition.

19.10% Efficiency and 80.5% Fill Factor Layer-by-Layer Organic Solar Cells Realized by 4-Bis(2-Thienyl)Pyrrole-2,5-Dione Based Polymer Additives for Inducing Vertical Segregation Morphology.

The morphology plays a key role in determining the charge generation and collection process, thus impacting the performances of organic solar cells (OSCs). The limited selection pool of additives to optimize the morphology of OSCs, especially for the emerging layer-by-layer (LbL) OSCs, impeding the improvements of photovoltaic performances. Herein, a new method of using conjugated polymers as the additives to optimize the morphology for improving the photovoltaic performances of LbL-OSCs is reported. Four polymers of PH, PS, PF, and PCl are developed with different side chains. These polymers exhibit poor performances as donor materials and additives in the BHJ devices, due to the unsuitable energy level alignment and unfavorable molecular interactions. By contrast, they can be served as efficient additives to optimize the PM6 fibril matrix for facilitating the penetration of BTP-eC9 and forming an intertwined D/A bicontinuous network with a vertical segregation. Such morphology is optimized by side chain engineering, which enables the progressive improvement of the charge separation and collection. As a result, adding a small amount of PCl as the additive, the optimized morphology contributes to a champion PCE of 19.10% with a high FF of 80.5%.

Effect of Cooling Rate on the Grain Morphology and Element Segregation Behavior of Fe-Mn-Al-C Low-Density Steel during Solidification

Mold with diameter sizes of 140 mm, 80 mm, 40 mm and 15 mm were designed to obtain the ingot of Fe-30Mn-10Al-1.1C low-density steel under different cooling rates. The influence of cooling rate on the grain morphology and elemental segregation behavior during the steel solidification process was analyzed by methods including inductively coupled plasma, scanning electron microscope and energy dispersive spectroscopy. The solidification sequence of the low-density steel was calculated by JMatPro 7.0 thermodynamic software. The results show that the microstructure of the steel is mainly austenite and contains a small amount of ferrite. The solidification order in the steel is: L → α, L → γ and α → γ, L → γ + MC. As the cooling rate increases from 1.69 °C/s to 10.28 °C/s, the ferrite phase precipitation increases by 16.7%, and the grain size decreases significantly, and in particular, the austenitic grain size decreases by 26%. With the increase in cooling rate, the microscopic segregation value of aluminum decreases approximately to 1. Additionally, the microscopic segregation of manganese showed a trend of increasing first and then decreasing. Microscopic segregation of Al and Mn can be improved significantly by increasing the cooling rate.

Phase segregation induced efficiency degradation and variability in mixed halide perovskite solar cells

Phase segregation is a critical phenomenon that influences the stability and performance of mixed halide perovskite based opto-electronic devices. In addition to the underlying physical mechanisms, the spatial pattern and randomness associated with the nanoscale morphology of phase segregation significantly influence performance degradation—a topic which, along with the multitude of parameter combinations, has remained too complex to address so far. Given this, with MAPbI1.5Br1.5 as a model system, here we address the influence of critical factors like the spatial randomness of phase segregation, the influence of ion migration, and the effect of increased non-radiative recombination at domains/interfaces. Interestingly, our analytical model and detailed statistical simulations indicate a unique trend—morphology evolution with increased phase segregation results, surprisingly, in a recovery in efficiency while non-radiative recombination at domains/domain boundaries results in efficiency degradation. Further, our quantitative and predictive estimates identify critical parameters for interface states beyond which device variability could be an important system level bottleneck. Indeed, these estimates are broadly applicable to systems that undergo phase segregation and have interesting implications to perovskite-based optoelectronic devices—from stability concerns to engineering approaches that attempt to arrest phase segregation.

High sensitivity of multi-sensing materials based on reduced graphene oxide and natural rubber: The synergy between filler segregation and macro-porous morphology

Elastomeric conductive composites (ECCs) based on carbonaceous fillers are very attractive and play a significant role in the field of smart sensors due to their excellent flexibility, high and wide-spectrum sensitivity as well as fast response to external stimuli. In this study, a lightweight and multi-sensing composite based on reduced graphene oxide/natural rubber (rGO/NR), is fabricated by a facile and cost-effective approach that combines the rGO assembling on rubber latex particles by graphene oxide in-situ reduction and mild drying of the resulting hydrogels. The resulting composites exhibit a reliable porous structure whereas the rGO is spatially distributed in a three-dimensional segregated morphology that percolates the samples. The composites are characterized by a low percolation threshold (<0.45 vol%), high sensitivity to compression strain (gauge factor equal to 77.64), organic solvents (i.e. toluene and tetrahydrofuran) and temperature (range of detectability is 35–90 °C). The elastomeric composites are proposed for the realization of innovative multi-purpose, wide-spectrum and high-sensitivity wearable sensors for monitoring the motion and temperature of human body in real time.

Emr1 regulates the number of foci of the endoplasmic reticulum-mitochondria encounter structure complex

The endoplasmic reticulum-mitochondria encounter structure (ERMES) complex creates contact sites between the endoplasmic reticulum and mitochondria, playing crucial roles in interorganelle communication, mitochondrial fission, mtDNA inheritance, lipid transfer, and autophagy. The mechanism regulating the number of ERMES foci within the cell remains unclear. Here, we demonstrate that the mitochondrial membrane protein Emr1 contributes to regulating the number of ERMES foci. We show that the absence of Emr1 significantly decreases the number of ERMES foci. Moreover, we find that Emr1 interacts with the ERMES core component Mdm12 and colocalizes with Mdm12 on mitochondria. Similar to ERMES mutant cells, cells lacking Emr1 display defective mitochondrial morphology and impaired mitochondrial segregation, which can be rescued by an artificial tether capable of linking the endoplasmic reticulum and mitochondria. We further demonstrate that the cytoplasmic region of Emr1 is required for regulating the number of ERMES foci. This work thus reveals a crucial regulatory protein necessary for ERMES functions and provides mechanistic insights into understanding the dynamic regulation of endoplasmic reticulum-mitochondria communication.

Functional characterization of the transcription regulator WhiB1 from Gordonia sp. IITR100.

WhiB is a transcription regulator which has been reported to be involved in the regulation of cell morphogenesis, cell division, antibiotic resistance, stress, etc., in several members of the family Actinomycetes. The present study describes functional characterization of a WhiB family protein, WhiB1 (protein ID: WP_065632651.1), from Gordonia sp. IITR100. We demonstrate that WhiB1 affects chromosome segregation and cell morphology in recombinant Escherichia coli, Gordonia sp. IITR100 as well as in Rhodococcus erythropolis. Multiple sequence alignment suggests that WhiB1 is a conserved protein among members of the family Actinomycetes. It has been reported that overexpression of WhiB1 leads to repression of the biodesulfurization operon in recombinant E. coli, Gordonia sp. IITR100 and R. erythropolis. A WhiB1-mut containing a point mutation Q116A in the DNA binding domain of WhiB1 led to partial alleviation of repression of the biodesulfurization operon. We show for the first time that the WhiB family protein WhiB1 is also involved in repression of the biodesulfurization operon by directly binding to the dsz promoter DNA.

Electromigration behavior of Cu/Sn–58Bi–1Ag/Cu solder joints by ultrasonic soldering process

Sn–58Bi–1Ag solder ribbon was prepared by twin-roll rapid solidification technology, and the ultrasonic soldering process was used to prepare Cu/Sn–58Bi–1Ag/Cu linear solder joints. Electron probe microanalysis (EPMA) and energy dispersive X-ray spectroscopy (EDS) were used to study the interface morphology of intermetallic compounds (IMC), Bi segregation, and solder joint matrix microstructure evolution with the current density of 1 × 104A/cm2 (25 °C). The result shows that the morphology of the anode IMC layer changes from scallop-like to hilly-like and then to flat-plate-like with the electrification time, and the thickness of IMC layer increases gradually. Bi is segregated toward the anode to form a Bi-rich layer. The cathode IMC layer is changed from a scallop to a zigzag, and its thickness is firstly increased and then decreased. The Sn is segregated toward the cathode to finally form a β-Sn-rich layer. Coarsening of eutectic microstructure (β-Sn+Bi) in solder joint matrix was caused by prolonged time. Based on linear fitting, the kinetic index n of the IMC layer of the anode and cathode is 0.432 and 0.491, respectively, and the growth mechanism is supposed to be volume diffusion. Ultrasonic soldering techniques can refine the Bi phase and increase the solubility of Bi in β-Sn, which slows down the formation of Bi-rich layers. The addition of Ag forms wedge-shaped and granular Ag3Sn intermetallic compounds, which hinders the growth of the Bi-rich layer and the Cu6Sn5 IMC, thus effectively inhibiting the electromigration process.

An Application of Fractal Theory to Complex Macrostructure: Quantitatively Characterization of Segregation Morphology

An Application of Fractal Theory to Complex Macrostructure: Quantitatively Characterization of Segregation Morphology

Phase segregation controlled semiconductor crystallization for organic thin film transistors

Abstract In this article, we provide an in-depth review of important works on phase segregation which occurs as a result of mixing organic semiconductors with polymeric additives. Throughout the discussion, the indispensable correlations among phase segregation, crystal growth, layer structure and film morphology are showcased using specific examples that mainly entail small-molecule organic semiconductors such as 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS pentacene) and 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene (diF-TES-ADT). The various factors that impact the phase segregation are analyzed, which include surface energy, solvent choice, additive nature, and substrate interaction. The beneficial effects of phase segregation on charge transport and operational stabilities of organic semiconductor based organic thin film transistors (OTFTs) are also assessed. We believe that the phase segregation examples discussed in this work shed light on optimizing the electrical performance of organic semiconductors and unlock favorable features useful for their application in high-performance organic electronics on flexible substrates.

Microstructures and mechanical properties of Ni/Fe dissimilar butt joint welded using the cold metal transfer

In this study, dissimilar butt joints were formed between as-rolled Inconel 718 and SUS 316 using cold metal transfer (CMT) with ERNiFeCr-2 filler metal at a welding speed of 5 mm s−1 and three different welding currents (130, 160 and 190 A). The morphology, microstructure, and mechanical properties of the joints and the mechanism by which the joint interface formed were studied. The results indicate that CMT welding parameters have an effect on the weld appearance and that the weld metal exhibits better wettability and spreadability at a welding current of 160 A. The interface between the weld metal and SUS 316 base metal was characterized by applying an optical microscopy (OM) and scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectrometry (EDS). The results revealed that no obvious diffusion of Ni and Fe ions was identified across the joint interface. The fractures that initiated in the joints during the tension testing formed in the heat-affected zone (HAZ) of the SUS 316 base metal, and the high-temperature tensile strength of the joint was observed to be 424 MPa, which is approximately 87.06% of that of SUS 316 base metal (487 MPa) and 67.19% of that of Inconel 718 base metal (631 MPa). In terms of the elongation, the joint (21.9%), Inconel 718 base metal (21.2%) and SUS 316 base metal (22.3%) elongations were similar. For comparison, the joint also was tested at room temperature, resulting in a tensile strength and elongation of 511 MPa and 27.5%, respectively. A spherical elemental Ni segregation morphology was clearly observed at the high-temperature fracture. Hardness studies demonstrated that the weld metal hardness is higher than that of the SUS 316 base metal.

The Arabidopsis anaphase-promoting complex/cyclosome subunit 8 is required for male meiosis.

Summary Faithful chromosome segregation is required for both mitotic and meiotic cell divisions and is regulated by multiple mechanisms including the anaphase‐promoting complex/cyclosome (APC/C), which is the largest known E3 ubiquitin‐ligase complex and has been implicated in regulating chromosome segregation in both mitosis and meiosis in animals. However, the role of the APC/C during plant meiosis remains largely unknown. Here, we show that Arabidopsis APC8 is required for male meiosis.We used a combination of genetic analyses, cytology and immunolocalisation to define the function of AtAPC8 in male meiosis.Meiocytes from apc8‐1 plants exhibit several meiotic defects including improper alignment of bivalents at metaphase I, unequal chromosome segregation during anaphase II, and subsequent formation of polyads. Immunolocalisation using an antitubulin antibody showed that APC8 is required for normal spindle morphology. We also observed mitotic defects in apc8‐1, including abnormal sister chromatid segregation and microtubule morphology.Our results demonstrate that Arabidopsis APC/C is required for meiotic chromosome segregation and that APC/C‐mediated regulation of meiotic chromosome segregation is a conserved mechanism among eukaryotes.

Correlation between morphology and anisotropic transport properties of diblock copolymers melts.

Molecular simulations of coarse-grained diblock copolymers (DBP) were conducted to study the effect of segregation strength and morphology on transport properties. It was found that in the strong segregation limit (i.e., high χN, where χ is the Flory-Huggins parameter and N is the degree of polymerization), the presence of the DBP interfaces imposes topological constraints similar to those of entanglements as manifested in the rheological signature of the polymer (i.e., a plateau modulus). Furthermore, compared to the behavior of isotropic melts, the crossover from Rouse to reptation scaling of the self-diffusion coefficient (D) parallel to the DBP interface takes place at a smaller N, an effect that depends on temperature and is more pronounced in the Lamellae morphology than in the hexagonal cylinder morphology. Additionally, it is shown that for an entangled melt (i.e., N ≫ Ne where Ne is the entanglement length) block retraction is instrumental for chains to diffuse parallel to the interface of lamellar layers. Lastly, it is found that the anisotropic viscosity of different morphologies is mostly affected by the orientation of the chains relative to the shear flow direction, exhibiting reduced values when chains align in the neutral or flow directions.

Peculiarities of Interactions of Alloying Elements with Grain Boundaries and the Formation of Segregations in Al–Mg and Al–Zn Alloys

The interactions between alloying elements and the symmetric edge boundary Σ5{210}[001] in Al alloys has been studied by the methods of the theory of the electronic-density functional. It has been shown that, in Al alloys, mechanisms of interactions of Mg and Zn with the grain boundary have been qualitatively different, which causes the peculiar morphology of the grain-boundary segregations. In the case of Mg, the deformational mechanism of interaction with the grain boundary is predominant, which facilitates the formation of relatively broad segregations. At the same time, in the case of Zn, the electronic mechanism, which is determined by directed chemical bonding, mainly contributes to interactions with the grain boundaries. As a result, it is more energetically advantageous for Zn atoms to occupy an interstitial position at the grain boundary or in the thin layer close to the grain boundary. The obtained results qualitatively explain the peculiar morphology of segregations at the grain boundary, which have been experimentally observed in the Al‒Mg and Al–Zn alloys.

SLM-manufactured 30CrMnSiA alloy: Mechanical properties and microstructural effects of designed heat treatment

Microstructures and mechanical properties of 30CrMnSiA alloy parts fabricated by forged annealing and selective laser melting (SLM) processes were compared in this study. SLM fabricated (SLMed) 30CrMnSiA alloy parts possess higher hardness and tensile strength than forged annealed (FAed) parts, however, a characteristic of low plasticity and impact toughness was observed in SLMed parts. Therefore, this research designed a reasonable heat treatment mode, which was divided into three periods to modify the microstructure in SLMed 30CrMnSiA alloy parts. The first period was repeated full annealing at 900 °C for 1 h to eliminate microstructure inhomogeneity, especially carbides segregation and ununiformed grain morphologies. The second period was air blast quenching from 900 °C to ambient temperature to achieve super saturation solid solution or martensite in parts. The last period was tempering at 650 °C for 1 h to fulfill martensite decarburization and carbides spheroidization. As a result, tempered sorbite as an equilibrium microstructure in ambient environment was obtained in SLMed 30CrMnSiA alloy parts. The optimum comprehensive mechanical properties of SLMed parts with an average hardness of 24.8 HRC, a tensile strength of 860 MPa, a plasticity of 16.9% and an impact toughness of 29.1 J were achieved by performing the designed heat treatment mode. It considerably enhanced the plasticity and impact toughness of SLMed 30CrMnSiA alloy parts, which were 1.41 and 2.55 times of parts without heat treatment. Accordingly, industrial applications of SLMed 30CrMnSiA alloy parts were supposed to be widened by this study.

Analysis of Chromosome Segregation, Histone Acetylation, and Spindle Morphology in Horse Oocytes.

The field of assisted reproduction has been developed to treat infertility in women, companion animals, and endangered species. In the horse, assisted reproduction also allows for the production of embryos from high performers without interrupting their sports career and contributes to an increase in the number of foals from mares of high genetic value. The present manuscript describes the procedures used for collecting immature and mature oocytes from horse ovaries using ovum pick-up (OPU). These oocytes were then used to investigate the incidence of aneuploidy by adapting a protocol previously developed in mice. Specifically, the chromosomes and the centromeres of metaphase II (MII) oocytes were fluorescently labeled and counted on sequential focal plans after confocal laser microscope scanning. This analysis revealed a higher incidence in the aneuploidy rate when immature oocytes were collected from the follicles and matured in vitro compared to in vivo. Immunostaining for tubulin and the acetylated form of histone four at specific lysine residues also revealed differences in the morphology of the meiotic spindle and in the global pattern of histone acetylation. Finally, the expression of mRNAs coding for histone deacetylases (HDACs) and acetyl-transferases (HATs) was investigated by reverse transcription and quantitative-PCR (q-PCR). No differences in the relative expression of transcripts were observed between in vitro and in vivo matured oocytes. In agreement with a general silencing of the transcriptional activity during oocyte maturation, the analysis of the total transcript amount can only reveal mRNA stability or degradation. Therefore, these findings indicate that other translational and post-translational regulations might be affected. Overall, the present study describes an experimental approach to morphologically and biochemically characterize the horse oocyte, a cell type that is extremely challenging to study due to low sample availability. However, it can expand our knowledge on the reproductive biology and infertility in monovulatory species.