Columnar Morphology Research Articles

Characterisations of the Al-Mn intermetallic phases formed under pulse magnetic fields solidification

In this research, the pulse electromagnetic fields were applied during the solidification of an Al-8Mn alloy. The changes of the microstructures due to different magnetic pulses applied were characterised using scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray tomography. The results show that without the magnetic field, the Al4Mn phases are thin plates in 3D space. At a magnetic field of 0.8T, the Al4Mn phases are transformed into a columnar morphology companied by fine and fragmented Al6Mn particles. At the magnetic flux density of 1.2T, the size of Al4Mn phases become more refined with their orientation gradually aligned towards the direction of the magnetic field, revealing that the pulse electromagnetic fields have a strong effect on the evolution of the Al-Mn phases in Al-8Mn alloy under solidification.

ВПЛИВ МАГНІТНОГО ПОЛЯ НА ЯКІСТЬ ВНУТРІШНЬОЇ МІКРОСТРУКТУРИ ПРИ ЛАЗЕРНОМУ СПЛАВЛЕННІ ПОРОШКУ

Thefast development of scientific and technical progress pushes the scientific community to search for alternative solu-tions and approaches for obtaining details using non-traditional technologies. One of the most common nowadays are additive technologies, better known as 3D printing from various powdered materials.When planning technological processes, in front of the developers always have relevant tasks which aimed to increasing the efficiency of the implementation of the 3D technology process, also improving the technological equipment. The main efforts are aimed at improving the quality indicators of the internal structure of alloyed products.The aim of this work is to improve the quality of the internal microstructure of fused primitives from the AlSi10Mg powder composition, due to the addition of a static magnetic field to the laser processing zone when implementing the DMLS technology.Taking into account the high complexity of physical processes and the large number of technological factors that affect the implementation of DMLS technology, the methods of mathematical statistics that have proven themselves well for solving this kind of tasks. When studying the effect of a static magnetic field on the focal area of a gas-powder flow, the optimal control parameters for the process of laser fusion of experimental samples from the AlSi10Mg powder composition were established.In this work, the effect of a static magnetic field on the microstructure of the AlSi10Mg powder composition was investi-gated. The results showed that the applied magnetic field leads to an increase in the relative density (a decrease in the porosity of the internal microstructure and a decrease in the spacing between dendrites in the treated material. In addition, with an increase in the intensity of the magnetic field, the share of grains with a columnar morphology decreases, and the share of equiaxed grains increases.

In Envelope Additive/Subtractive Manufacturing and Thermal Post-Processing of Inconel 718.

This study investigated the application of an in envelope additive/subtractive (LPBF) manufacturing method (Matsuura LUMEX-Avance-25) to fabricate IN718 benchmarking coupons. The coupons were then examined comprehensively for surface finish both with and without high-speed micro-machining. The microstructure of the manufactured IN718 coupons was investigated thoroughly in the as-fabricated condition and following three different standard and one non-standard post-processing heat treatments. As built coupons revealed columnar grain morphology mainly along the <100> direction with a cellular dendritic sub-grain structure and without any strengthening precipitates. Grain size, aspect ratio, and texture were maintained after each of the applied four heat treatments. Only one of the standard heat treatments resulted in the δ phase formation. The other three heat treatments effectively dissolved the Laves phase preventing the δ formation while promoting the formation of γ′/γ″ precipitates. Despite the observed differences in their microstructures, all of the heat treatments resulted in similar yield and ultimate tensile strength values that ranged between 1103−1205 MPa and 1347−1387 MPa, respectively. These values are above the minimum requirements of 1034 MPa and 1241 MPa for the wrought material. The non-standard heat treatment provided the highest elongation of 24.0 ± 0.1% amongst all the heat-treated specimens without a significant loss in strength, while the standard heat treatment for the wrought parts resulted in the lowest elongation of 18.3 ± 0.7% due to the presence of δ phase.

Inclusion Polymerization of Pyrrole and Ethylenedioxythiophene in Assembled Triphenylamine Bis-Urea Macrocycles

Herein, two different monomers, pyrrole (Py) and ethylenedioxythiophene (EDOT), are loaded into a self-assembled bis-urea host 1 and oxidatively polymerized within its nanochannels, dramatically changing the properties of the crystalline complexes. Molecular dynamics (MD) simulation of both monomers within the channel demonstrates that they diffuse through the confinement upon applying thermal energy, which may facilitate the polymerization reaction. The structures of these host–guest complexes are characterized before and after polymerization using solid-state and photophysical measurements. The host maintains its columnar morphology during polymerization at 90 °C using iodine as an oxidizing agent. Intriguingly, upon dissolution of the host and recovery by filtration, the polymers exhibit memory of their nanoreactor environment, displaying unusual order by scanning electron microscopy, powder X-ray diffraction, and small- and wide-angle X-ray analysis. Solid-state 13C cross-polarized magic angle spinning NMR suggests that polypyrrole (PPy) exhibits primarily α,α′ linkages with some contributions from the quinoid form. Similarly, poly(ethylenedioxythiophene) (PEDOT) also exhibits formation of primarily α,α′ linkages with minor quinoid contributions. Both the 1·PPy and 1·PEDOT crystals show a 103-fold increase in conductivity to ∼10–6 S/cm versus host 1 crystals, which are nonconductive ∼10–9 S/cm. Overall, supramolecular polymerization strategies have the potential to readily modulate the properties of nanostructured materials.

A “heat set” Zr-Diimide based Fibrous Metallogel: Multiresponsive Sensor, Column-based Dye Separation, and Iodine Sequestration

Sensing and monitoring hazardous contaminants in water and radioactive iodine sequestration is pivotal due to their detrimental impact on biological ecosystems. In this context, herein, a water stable zirconium-diimide based metallogel (Zr@MG) with fibrous columnar morphology is accomplished through the “heat set” method. The presence of diimide linkage with long aromatic chain manifests active luminescence properties in the linker as well as in the supramolecular framework structure. The as-synthesized Zr@MG xerogel can selectively detectCr2O72- (LOD = 0.52 ppm) and 2,4,6-trinitrophenol (TNP) (LOD = 80.2 ppb) in the aqueous medium. The Zr@MG paper strip-based detection for Cr2O72- and nitro explosive makes this metallogel reliable and an attractive luminescent sensor for practical use. Moreover, a column-based dye separation experiment was performed to show selective capture of positively charged methylene blue (MB) dye with 98 % separation efficiency from the mixture of two dyes. Also, the Zr@MG xerogel showed effective iodine sequestration from the vapor phase (232 wt%).

Microstructural Investigations of VO2 Thermochromic Thin Films Grown by Pulsed Laser Deposition for Smart Windows Applications

The structural properties of VO2 thin films, grown on either LSAT or Si substrates by pulsed laser deposition (PLD), are elucidated by means of transmission electron microscopy (TEM) methods. The TEM observations confirmed the successful growth of VO2 by PLD in variable thicknesses, by optimizing the O2 partial pressure and growth temperature. The films adopt a columnar polycrystalline morphology with narrow columns, up to the film thickness height. Four VO2 polymorphs have been detected by electron diffraction and high-resolution TEM (HRTEM) analysis, with M1 being by far the most abundant phase. Post-experimental strain measurements in HRTEM images have revealed that the actual residual strain is minimized due to the columnar morphology of the VO2 grains, as well as intrinsic oxide layers in the VO2/Si epitaxy. The TEM outcomes confirmed the complementary electrical and magnetic measurements in the films, where a transition from a monoclinic M1 to a rutile VO2 R phase has been identified, influenced by the initial percentage of phases in thick VO2 films.

Effect of cyclic DHT on microstructural evolution and mechanical properties of Ti44Al6Nb1Cr2V alloy

To clarify effects of microstructure on tensile properties of high Nb-TiAl alloys after cyclic directional heat treatment (DHT), Ti44Al6Nb1Cr2V alloys are conducted DHT for 1, 2 and 3 cycles (DHT-1, DHT-2 and DHT-3) at 1730 K, respectively. The pulling rate is set as 4.17 µm/s. Results show the phase component mainly consists of γ, α2 and B2 phases for Ti44Al6Nb1Cr2V alloy after cyclic DHT. Directional microstructure is obtained. Lamellar clusters are columnar and B2 phases present banded morphology. They are distributed alternately. As DHT cycles increase, the radial size of lamellar clusters enlarges as well. Blocky γ phases grow up and coarsen. At room temperature, good tensile properties are obtained in Ti44Al6Nb1Cr2V alloys after cyclic DHT. Tensile strength is about 609 MPa for DHT-1 alloy. Their fractures show that cleavage microstructure is mainly formed for cracks propagation during tensile test. Both DHT-1 and DHT-3 alloys present good tensile properties stability at 900 °C. Their yield strength, ultimate tensile strength and elongation are about 355–487 MPa-3.3% and 355–421 MPa-1.5%, respectively. Combining their microstructures with fractures, it concludes for their tensile properties difference that many blocky γ phases precipitate and coarsen during cyclic DHT, which decreases deformation coordination between lamellar clusters and banded B2 phases. Some microcracks form easily near B2 phases. Consequently, tensile properties of DHT-3 alloy decrease. This study will provide basic experimental data and theoretical support for high Nb-TiAl alloys to further optimize DHT parameters and improve their mechanical properties.

Columnar Dendrite Morphology and Solute Concentration of GH3039 Nickel-Based Superalloys during Wire and Laser Additive Manufacturing: Insights from Phase Field Simulations

Columnar Dendrite Morphology and Solute Concentration of GH3039 Nickel-Based Superalloys during Wire and Laser Additive Manufacturing: Insights from Phase Field Simulations

Controlling grain size, morphology and texture in additively manufactured β-titanium alloy with super transus hot isostatic pressing

Titanium alloys produced by Additive Manufacturing (AM) are often characterised as having coarse columnar grain structures on account of the prevailing thermal conditions at the time of solidification. This work investigates whether thermal post processing treatments above the β-transus temperature at both standard atmospheric pressure and 1500 bar pressure (Hot Isostatic Pressing – HIPing) can refine the columnar morphology in the high strength Ti-3Al-8V-6Cr-4Mo-4Zr (Beta-C/ASTM Grade 19) alloy produced by AM. Heat treatment at standard atmospheric pressure was ineffective in modifying the coarse columnar microstructure but HIPing was found to promote new equiaxed grains and significantly refine the grain size by up to 72.5% compared to the as-built component. The strong dominant <001> texture characteristic of the as-built (and heat treated) alloy was weakened and shifted towards <103> with a 5-fold reduction in texture intensity after the HIPing process. EBSD analysis reveals evidence of grain recrystallisation processes including but not limited to discontinuous dynamic recrystallisation (DDRX) which may be associated with pore collapse. Primitive columnar grains were also shown to contain numerous substructures which may have formed through dynamic recovery (DRV).

Gigantoproductid shell spiral and microstructure of tertiary layer: evaluation as taxonomical characters

ABSTRACTBrachiopod taxonomy is based on descriptions of shell morphology and key characters, but diagenesis generally modifies or erases some of them, hindering brachiopod identification. Brachiopods that are taxonomically related usually present shells with similar appearance but can differ in size (i.e., Rhynchonellata). Some aspects of morphology – for example the angular measurement of the curvature of the shell or details of shell microstructure – could aid taxonomic identification. Gigantoproductids, which lack a robust taxonomy, have the largest shells among brachiopods and are ideal for this kind of study because of their gigantic size and morphological variability. Furthermore, they have a great abundance and worldwide distribution during the mid-Carboniferous. More than 700 samples have been collected from Sierra Morena (Spain), Montagne Noire (France) and Adarouch (Morocco) identifying up to six gigantoproductid genera:Globosoproductus,Semiplanus, Kansuella?,Latiproductus,GigantoproductusandDatangia. Microstructural features from 170 thin sections belonging to gigantoproductid ventral valves have been studied, and six crystal morphologies have been distinguished within the tertiary layer: subhorizontal, imbricated, crenulated, acicular, short and long columnar morphologies. Moreover, 23 complete shells from all genera have been selected to investigate shell size and curvature. Results from this study emphasise that shell size, curvature and crystal shape are taxa-related. Finally, a remarkable morphological change in the gigantoproductid populations from the western Palaeo-Tethys occurred during the Viséan–Serpukhovian, from thin-shelled genera with subhorizontal morphology (Viséan) to thick-shelled genera with a tertiary layer consisting of long columnar crystals (Serpukhovian). This study proves that microstructure, maximum thickness and shell spiral characterisation are robust characters when applied to gigantoproductid taxonomy, but also have great potential in other brachiopod groups.

Synthesis and characterization of the ceramic refractory metal high entropy nitride thin films from Cr-Hf-Mo-Ta-W system

High entropy alloy and nitride coatings from the Cr-Hf-Mo-Ta-W system were deposited by reactive magnetron sputtering from elemental segmented targets. The study aimed to investigate the effects of deposition parameters on the microstructure and mechanical properties of this novel multicomponent material. Samples without nitrogen flow and under different nitrogen flows were prepared in two series of samples prepared at ambient temperature and at 750 °C. The proportion of metallic elements varied with increasing nitrogen flow. The nitrogen content revealed saturation below 50 % under high flow. The thin films showed a different microstructure depending on the deposition conditions, from a single nanocrystalline bcc phase (a = 3.174 Å) in the metallic sample prepared at 750 °C without nitrogen flow, through an amorphous structure under low nitrogen flow to a major nanocrystalline NaCl-type fcc nitride phase (a = 4.186–4.268 Å, in agreement with the ab-initio predicted values) in samples deposited under high nitrogen flow. The cross-section morphology of the amorphous sample was very homogeneous, while the samples with a major fcc nitride phase showed a typical columnar morphology. Overall, the films revealed hardness and Young's modulus up to 20.3 GPa and 471 GPa, respectively, for the fcc nitride coating. The experimental values of Young's modulus were in good agreement with the values of directional [100] Young's modulus obtained by ab-initio calculations. The results of our research showed that coatings consisting of bcc and fcc phases could be produced by magnetron sputtering with interesting mechanical properties such as high Young's modulus. Moreover, the results contribute to the understanding of the influence of the nitrogen flow on the microstructural features such as crystallite size, vacancies in the lattice, and lattice parameter change.

Metakaolin-Reinforced Sulfoaluminate-Cement-Solidified Wasteforms of Spent Radioactive Resins—Optimization by a Mixture Design

Cement solidification is a main technique for radioactive waste treatment to reduce its risk to the environment and human health. However, this method underperforms when dealing with spent radioactive ion-exchange resin, taking much space, and costing much money for final disposal. In this work, simulated spent radioactive resin was solidified using a metakaolin-reinforced sulfoaluminate cement system, which was optimized by a mixture design based on the effects of components and parameters, and the durability of solidified wasteforms was assessed in terms of strength and Cs(I) leaching. Solidified by an optimized formula of 40 wt.% spent resin, 55.8 wt.% sulfoaluminate cement, 2.2 wt.% metakaolin, and 2 wt.% water reducer, the resin loading in wasteforms reached 64% and the compressive strength 13.7 MPa. The dominant mineral phases of hydration products were ettringite crystalline of acicular and columnar morphology, with small amounts of scattered amorphous clusters of aluminum gels and C–S–H gels. Metakaolin, a source of aluminum, promoted the growth of ettringite, which facilitated (1) the encapsulation of resin beads with high strengths, even in acidic environments or during frequent freezing-thawing, and (2) the retention of Cs(I), with a 42 day leaching rate of 2.3 × 10−4 cm/day. This work offers a technical justification for spent resin solidification in the metakaolin-reinforced sulfoaluminate cement system, which is an applicational solution for the efficient treatment of radioactive waste.

Impact of the B/C-doping ratio on the microstructure, mechanical properties, and cutting performance of AlTiN-based coatings

Certain element doping is a facile and powerful vehicle for tailoring the organization and properties of hard coatings. This research fabricated AlTiBCN coatings with various B/C doping ratios (the boron-carbon incorporation totaled 10 at.%) and explored the effect law of varying B/C ratios on the coatings' microstructure, mechanical properties, tribological, and cutting performances. All coatings exhibited a mixed structure of cubic and fibrous zincite phases, with the major phase being w- Al(Ti)N and the minor phases being c-Al(Ti)N and c-Ti(C, N). Besides, along with the increase in C-doping proportion, the coating organization shifted from a featureless glassy pattern to a fine-grained columnar crystal morphology. Boron was mainly found as -BN in the coatings, while carbon was mostly found as c-Ti(C, N) replacement solid solution (B/C ratio≤2.5:1, 0:10) and amorphous C (B/C ratio≤1:2.5, 0:10). According to the properties results, (1) AlTiBCN coating with a B/C ratio of 1:1 had the optimal mechanical, tribological, and cutting performance; (2) AlTiBCN coating with a B/C ratio≥ 2.5:1 and 10:0 had higher hardness but poorer coating brittleness and tribological properties due to excessive α-BN; (3) At B/C ratios≤ 1:2.5 and 0:10, the mechanical properties of its coatings dropped sharply, which means the coating's hardness, toughness, and wear resistance are aggravated by the strong softening effect of α-C.

Correlation between microstructural heterogeneity and anisotropy of mechanical properties of laser powder bed fused CoCrFeMnNi high entropy alloy

The unique microstructure of face-centered-cubic (FCC) structured alloys fabricated by laser powder bed fusion (LPBF) contributes to outstanding mechanical performances, but inevitably leads to anisotropy of mechanical properties. In this study, the relationship between the hierarchical microstructure and mechanical properties along the horizontal, diagonal, and vertical directions of the LPBF-built CoCrFeMnNi high entropy alloy (HEA) were qualitatively and quantitatively investigated. The horizontal samples exhibit the highest yield strength (YS) and the lowest elongation, while the vertical samples show the lowest YS and a slightly lower elongation than the diagonal samples, which are nearly two times the horizontal samples. Among the microstructural features at multiple length scales, both the columnar grain morphology and texture determine the anisotropy of mechanical properties. For the first time, the volume-weighted (V–W) average grain size was used to estimate the YS and critical twinning stress (CTS) of the LPBF-built CoCrFeMnNi alloy with a complex grain size distribution. The V–W average grain size exhibited high accuracy in calculating the YSs of the diagonal and vertical samples as well as CTSs along all the three directions. For the horizontal sample, the grain morphology dominates over texture during deformation, which is the same for the diagonal and vertical samples at the early stage of deformation. The texture plays a more important role at the late stage of straining.

Comparative study of microstructure and mechanical properties using a novel filler rod ER 4943 and autogenously butt welded joint during laser welding of AA 6061-T6 in 1G position

A 4 mm thick heat-treated aluminum alloy AA 6061-T6 has been butt welded in 1 G position using a 12-kW disk laser. A novel high magnesium content filler rod ER 4943 belonging to the 4xxx series of aluminum alloys has been used to investigate its effects on microstructure, mechanical properties and alloying elements segregation in the fusion zone. The results have also been compared with an autogenous laser butt welded joint case. A solidified microstructure has been analyzed by EBSD. It was found that additional solute content brought by filler rod into the molten pool caused a higher proportion of equiaxed grain zone after solidification due to an enhanced constitutional supercooling ahead of solid/liquid interface. For an autogenous butt welded joint, the columnar morphology sustained for a longer period and a narrower equiaxed grain zone were observed. Point analysis by an EDS revealed a higher retention of magnesium and silicon inside the solid solution with filler rod welding. In addition, the area map of magnesium also observed a denser distribution of magnesium inside the fusion zone. Both hardness and tensile strength of filler rod welded joint were higher than without filler rod welding. It is believed that a higher proportion of equiaxed grains and additional solute content within the solid solution are the primary causes of higher mechanical properties owing to hampered dislocation motion. The much desirable results obtained in terms of microstructure and mechanical properties could be of great significance to the welding industry.

Multi-component low and high entropy metallic coatings synthesized by pulsed magnetron sputtering

This paper presents the findings of the synthesis of multicomponent (Al, W, Ni, Ti, Nb) alloy coatings from mosaic targets. For the study, a pulsed magnetron sputtering method was employed under different plasma generation conditions: modulation frequency (10 Hz and 1000 Hz), and power (600 W and 1000 W). The processes achieved two types of alloy coatings, high entropy and classical alloys. After the deposition processes, scanning electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy techniques were employed to find the morphology, thickness, and chemical and phase compositions of the coatings. Nanohardness and its related parameters, namely H3/Er2, H/E, and 1/Er2H ratios, were measured. An annealing treatment was performed to estimate the stability range for the selected coatings. The results indicated the formation of as-deposited coatings exhibiting an amorphous structure as a single-phase solid solution. The process parameters had an influence on the resulting morphology—a dense and homogenous as well as a columnar morphology, was obtained. The study compared the properties of high-entropy alloy (HEA) coatings and classical alloy coatings concerning their structure and chemical and phase composition. It was found that the change of frequency modulation and the post-annealing process contributed to the increase in the hardness of the material in the case of HEA coatings.

Scan strategies in EBM-printed IN718 and the physics of bulk 3D microstructure development

Three-dimensional (3D) characterization provides opportunities for understanding processing-structure relationships in additively manufactured (AM) materials. Bulk samples of Inconel 718 were fabricated via electron beam melting (EBM) in order to study microstructural development as a function of energy input and beam scan strategy. TriBeam tomography of bulk Inconel 718 microstructures built under steady-state growth conditions reveals the sensitivity of microstructure formation and evolution to machine process parameters. In this study, samples manufactured using a narrow range of energy input per unit build area result in varied grain morphologies and crystallographic textures. Using TRUCHAS, a thermal simulation software, the thermal history of bulk scan strategies was predicted, and combined with a calibrated microstructure-processing map to accurately predict bulk grain morphologies. The solidification parameters and the 3D measured nucleation density are used to predict the transition between columnar and equiaxed grain morphologies, providing a process map to guide AM parameter choices to locally control as-printed microstructure. A two-dimensional metric for characterizing bulk grain morphology was also found to agree well with predictions from the process map calibrated by 3D data. Combined with 3D tomography and thermal modelling, the physics of structure development were understood at a new level of detail with respect to the competing processes of grain nucleation and epitaxial growth.

Structure and fracture toughness of TiAlN thin films deposited by deep oscillation magnetron sputtering

TiAlN thin films were deposited on Si(100) and AISI 304 austenitic stainless steel substrates at the low deposition temperature below 250℃ by the deep oscillation magnetron sputtering (DOMS), respectively. The peak sputtering power changed from 58.7 kW to 129.9 kW by adjusting the oscillation voltage on-time (τon) / off-time (τoff) ratio with 6–12 μs to 30 μs. All TiAlN thin films have a face centered cubic structure with a composition of Ti0.22Al0.28N0.50. With increasing the peak powers, a transit of the columnar morphology in Zone I with the preferred orientation of c-TiAlN(111) to a compact morphology in Zone T with c-TiAlN(200) was characterized. The hardness, residual stress, and H/E and H3/E2 ratios of TiAlN thin films increased with the maximal values obtained at the peak power of 90.2 kW, and then slightly decreased. Correspondently, the fracture toughness (KIC) of TiAlN thin films on Si(100) and AISI 304 stainless steel increased firstly from 0.56 MPa∙m1/2 to 1.10 MPa∙m1/2 and from 0.58 MPa∙m1/2 to 1.08 MPa∙m1/2 as the structure from Zone I with c-TiAlN(111) to Zone T with c-TiAlN(200), and then decreased to 0.94 MPa∙m1/2 and 0.71 MPa∙m1/2 at the structure of Zone T with c-TiAlN(200), respectively. The higher KIC values of Ti0.22Al0.28N0.50 thin films in Zone T were achieved on Si(100) and AISI 304 stainless steel at 90.2 kW. The excellent mechanical properties of TiAlN thin films on Si(100) and AISI 304 stainless steel substrates were carried out by using DOMS at the low deposition temperature.

Quantitative Microstructural Characterization of Precipitates and Oxide Inclusions in Inconel 625 Superalloy Additively Manufactured by L-PBF Method

In this study, we perform quantitative characterization of precipitates and oxide inclusions in Inconel 625 additively manufactured by the laser powder-bed fusion (L-PBF) process. The application of different microscopy techniques allowed us to characterize the microstructure at micro- and nano-scale in the as-built and stress-relieved condition and correlate the features of grains and cellular substructure with parameters of particles along the planes parallel and perpendicular to the build direction. The optimized imaging conditions and image analysis procedure allowed easily distinguishing precipitates and oxide inclusions and performing their quantitative analysis. The results showed that intercellular areas are the preferential sites of precipitation of the Laves phase and NbC carbides with diameters in the range of 10 to 440 nm. Moreover, aluminum oxide inclusions with diameters in the range of 30 to 300 nm are randomly distributed. Regardless of the processing conditions of the examined samples, the influence of the stress-relief annealing on the secondary phases was not observed. In both the as-built and stress-relieved samples, the size of precipitates is in submicrometer scale. The analysis provided detailed information about the parameters of particles depending on the orientation versus the build direction. It was demonstrated that despite the tendency for columnar grain morphology and the anisotropy of the cellular substructure, the particle distribution is almost uniform throughout the volume of the additively manufactured L-PBF Inconel 625.Graphical

Redox-Active Covalent Organic Frameworks with Nickel-Bis(dithiolene) Units as Guiding Layers for High-Performance Lithium Metal Batteries.

Combining the chemistry of metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) can bring new opportunities for the design of advanced materials with enhanced tunability and functionality. Herein, we constructed two COFs based on Ni-bis(dithiolene) units and imine bonds, representing a bridge between traditional MOFs and COFs. The Ni-bis(dithiolene)tetrabenzaldehyde as the 4-connected linker was initially synthesized, which was further linked by 4-connected tetra(aminophenyl)pyrene (TAP) or 3-connected tris(aminophenyl)amine (TAA) linkers into two COFs, namely, Ni-TAP and Ni-TAA. Ni-TAP shows a two-dimensional sql network, while TAA is a twofold interpenetrated framework with an ffc topology. They both exhibit a high Brunauer-Emmett-Teller surface area (324 and 689 m2 g-1 for Ni-TAP and Ni-TAA, respectively), a fairly good conductivity (1.57 × 10-6 and 9.75 × 10-5 S m-1 for Ni-TAP and Ni-TAA, respectively), and high chemical stability (a stable pH window of 1-14 for Ni-TAA). When applied in lithium metal batteries as an intermediate layer for guiding the uniform Li electrodeposition, Ni-TAP and Ni-TAA displayed impressive lithiophilicity and high Li-ion conductivity, enabling the achievement of smooth and dense Li deposition with a clear columnar morphology and stable Li plating/stripping behaviors with high Li utilization, which is anticipated to pave the way to upgrade Li metal anodes for application in high-energy-density battery systems.