Nb-silicide-based alloys are promising ultrahigh-temperature structural materials for aerospace applications. However, conventional electron beam powder bed fusion (EB-PBF) typically leads to insufficient silicide precipitation, resulting in unsatisfactory high-temperature mechanical properties. In this study, crack-free Nb-16Si-10Ti-10Zr-3Cr-3Al-3Hf (at%) specimens with dimensions of 80 x 20 x 35 mm3 were successfully fabricated by EB-PBF using an in-situ remelting strategy. During the in-situ remelting EB-PBF process, each layer was scanned twice to impose an in-situ heat treatment effect during forming, which effectively broadened the heat-affected zones and promoted the secondary precipitation of silicides. Consequently, the silicide fraction increased from 10% to 17.3% with only a 4.69% extension in processing time. At 1250 degrees C, the yield strength and ultimate tensile strength were remarkably enhanced by 328% and 223%, respectively. The superior hightemperature strength is attributed to the combined effects of precipitation strengthening and an inferred mixed dislocation strengthening, involving both dislocation cutting and bypassing mechanisms. This in-situ remelting EB-PBF process enables outstanding elevated-temperature tensile properties in as-built Nb-silicide alloys without additional post-heat treatments, significantly improving the feasibility of additive manufacturing for complex high-temperature Nb-silicide components.

Inspired by the nacre-like "brick-and-mortar" architecture characterized by the orderly arrangement of hard platelets within a soft matrix, this study presents a novel approach to fabricating graphene nanosheet-reinforced composites. These composites feature a highly oriented and uniformly distributed arrangement within a resin matrix, achieved via a high-precision digital light processing (DLP) method. Computational simulations of laminar flow dynamics within graphene nanosheet-reinforced resin were conducted to establish optimal platform control parameters. Mechanical testing results demonstrate significant improvements in both tensile and flexural properties across four different photosensitive resins (MED, RG, BIO, and HTL), with tensile strength increase exceeding 50% in all compositions. In addition, the tribological performance of the resins is significantly enhanced by the incorporation of highly oriented graphene. Notably, the MED resin exhibited excellent tribological performance, with the coefficient of friction (COF) reduced from 0.63 to 0.024 (a 96.2% reduction) and the wear volume decreased by 98.8%, placing this improvement among the leading results reported for carbon-based reinforcement strategies in 3D-printed tribological applications. Furthermore, by employing focused ion beam (FIB) planar ion bombardment to progressively remove the surface resin matrix, the graphene nanosheets originally embedded beneath the surface are exposed, enabling visualization of their spatial distribution. Thus, this approach provides a universal and generalizable methodology for characterizing nanosheet orientation arrangement in reinforced composite materials. The developed nacre-inspired "brick-and-mortar" structured composite with integrated strength, toughness, and wear resistance has great promise for applications in high-tech fields such as biomanufacturing, aerospace, and robotics, demonstrating broad application prospects.

ABSTRACT Biomimetic liver models that faithfully recapitulate physiological structure and function are vital for assessing drug‐induced hepatotoxicity. Existing liver models usually lack vascular and biliary dual systems, the challenge of which lies in achieving precise multicellular spatial organization, stable lumens, and functionally coupled interactions among hepatic parenchyma, vasculature, and bile ducts. Here, we developed a 3D‐printed vascular‐biliary‐incorporated liver‐on‐a‐chip (VBL) by projection micro‐stereolithography (PµSL) printing strategy to construct a heterogeneous liver model. The vascular‐biliary‐incorporated liver‐on‐a‐chip features mesh‐walled microtubes with high permeability and vessel‐like elasticity. The mesh‐like structure enhances surface wettability and enables endothelial cells and biliary epithelial cells to infiltrate the microtubes under capillary‐driven flow to form functional microvasculature and microbile ducts. By further incorporating hepatic parenchyma, the liver model establishes direct heterotypic cell–cell contact among hepatocytes, endothelial cells, and biliary epithelial cells, generating well‐defined and interconnected hepato‐vascular‐biliary compartments under perfused culture conditions. Additionally, the vascular‐biliary‐incorporated liver‐on‐a‐chip exhibits enhanced hepatic functions, multicellular crosstalk, and the formation of bile canaliculi‐like structures, conferring increased sensitivity to drug‐induced hepatotoxicity. Collectively, the vascular‐biliary‐incorporated liver‐on‐a‐chip enables the stepwise construction of a biomimetic liver model, providing a new platform for drug‐induced hepatotoxicity assessment.

With the advancement of additive manufacturing (AM) technology, the oxidation resistance of superalloys became increasingly important. Haynes 230 alloy, which was widely used in extreme environments because of its excellent high-temperature properties, was of considerable interest because of its oxidation behavior. In this study, Haynes 230 alloy samples were fabricated by laser powder bed fusion (LPBF) to investigate the effect of powder size on oxidation behavior and to elucidate the mechanisms underlying crack suppression and oxidation resistance. The results showed that samples fabricated from coarse powders (diameter >= 40 mu m) exhibited better oxidation resistance than those fabricated from fine powders (diameter <= 14 mu m). The oxidation process underwent three stages: diffusion-controlled oxide growth, oxide scale spallation, and oxidation dominated by gas-phase reactions. The oxide scale consisted of three distinct layers: an inner Al2O3 layer, a middle Cr2O3 layer, and an outer TiO2 layer. Oxide scale spallation was initiated in regions containing microcracks, and its severity increased with increasing microcrack density. Moreover, samples fabricated from coarse powders showed a lower crack density. Grain refinement hindered microcrack propagation and alleviated thermal stress, thereby providing a controllable means of tailoring oxidation resistance. These findings provided a theoretical basis for powder size selection in AM and offered guidance for improving the service performance of superalloys in extreme environments.

Strong textures are always the inevitable hurdles in achieving isotropic performance for pure tungsten (W) manufactured by laser powder bed fusion (LPBF) or electron beam powder bed fusion (EB-PBF). Intrinsically, the ultimate texture is determined by the characters of original molten pool and so in this work, the correlation between the molten pool morphology of pure tungsten during LPBF and EB-PBF process and the ultimate solidification microstructure was explored by experiments and finite element analyses (FEAs). The molten pool morphology of LPBF W was deep and narrow, being called the keyhole mode, and in contrast, the molten pool morphology of EB-PBF W was shallow and wide, being called the conduction mode. According to FEAs, we found that the direction of temperature gradient was generally vertical to the contour line of molten pool bottom towards the center of the molten pool surface. In the keyhole mode molten pool during LPBF process, due to the large depth-to-width ratio, the direction of temperature gradient, pointing centripetally from the bottom contour line to the upper center of the molten pool, changed sharply with the shrinking of molten pool during solidification process, consequently, the primary dendrites, initially vertical to the contour line of molten pool bottom, would collide with each other during their growing along the rapidly varying direction of the temperature gradient, and thus the unidirectional epitaxial growth of primary dendrites would be interrupted, which resulted in bowl-shaped grains and < 111 > textures. Differently, the direction of temperature gradient would change more slowly along the shrinking of molten pool during the solidification process of EB-PBF process for the depth-to-width ratio was much smaller in the conduction mode than that in the keyhole mode, so the unidirectional epitaxial growth of the primary dendrites could continue without frequent interruption, and thus typical columnar grains and <111>, < 001 > binary textures were formed in EB-PBF W. The results about the correlation of the molten pool morphology and the ultimate microstructure might conduce to find novel approaches for tailoring the textures of tungsten prepared by additive manufacturing.

High-pressure emulsion separation is vital for crude oil treatment and engine fuel dehydration, and yet is hindered by materials with poor pressure resistance and difficulty in handling highly viscous oils. Herein, via simple and efficient surface modification, we fabricate two physicochemically robust sintered glass filters with superhydrophilic and superoleophilic surfaces, respectively. Under 3 bar pressure, the superhydrophilic filter rapidly separates various oil-in-water emulsions, achieving 99.4% efficiency and a flux of 21,139 L m(-2) h(-1) for a crude emulsion. Meanwhile, tackling the more challenging water-in-oil emulsions, the superoleophilic filter not only enables ultra-fast separation from low-viscosity oil (e.g., a flux up to 50,798 L m(-2) h(-1) and 99.8% efficiency for an n-hexane emulsion), but also excels with highly viscous oils, maintaining > 99.3% efficiency for refrigerator and dimethylsilicone oils, as well as demonstrating a 97.7% dehydration rate for ultra-high viscosity crude oil (11,557 mPa s). Crucially, we propose a paradigm shift in the separation mechanism: actively utilizing high pressure to drive separation, rather than merely tolerating it. This work provides a new strategy and valuable guidance for the treatment of viscous oils and advanced filtration.

Droplets exhibit distinct wetting characteristics and transport behavior on solid substrates at the macroscopic and microscopic scales. This behavior is critical for understanding liquid mass transfer on fibrous membranes. To better understand and control the mass transfer of liquids on fibrous membranes, we combined in situ visualization techniques with multiphase flow simulations. This approach enabled us to systematically explore the effects of various factors, including fiber wettability, fiber diameter, and fiber spacing, on liquid transfer behavior. Furthermore, we successfully elucidated the transfer mechanisms governing droplet transport on individual fibers and between adjacent fibers. Based on our findings, we constructed composite fiber membranes with varying fiber diameters and wettability structures. The validity of the proposed approach was verified by comparing fog collection, droplet wetting, and liquid permeation efficiency. Consequently, this study establishes a transferable cross-scale framework and proposes a general design strategy for constructing fibrous membranes tailored to diverse application requirements.

In elastocaloric (eC) refrigeration, conventionally fabricated NiTi alloys require complex deformation processing such as forging and rolling to achieve desired properties, compromising the intricate geometries for industrial applications. To overcome this limitation, we develop a four-dimensional-printed NiTi alloy with encoded (4D-ped) microstructures, fabricated in a near-net-shape manner. Benefiting from the multi-scale microstructures including tailored grain size and fraction of Ni4Ti3 nanoparticles, this alloy evades the trade-off between cooling capacity and energy efficiency. The novel architecture enables a stage-wise phase transformation (PT) mechanism, leading to a quasi-linear mechanical response. This unique architecture triggers a novel eC mechanism other than conventional AM NiTi: the superior properties arise not only from the reduced transformation energy barrier enabled by R-phase nanodomain formation due to fine Ni4Ti3 nanoparticles in coarse grains, but also from the enhanced yield strength induced by dense Ni4Ti3 precipitation in fine-grained domains, which promotes a stable stress-induced PT and enables effective latent heat absorption. As a result, the 4D-ped NiTi achieves a temperature drop of ∼15 K and a material coefficient of performance of 36.5, delivering superior eC performance compared with existing AM alloys. These findings advance the fabrication of high-performance eC structures with intricate geometries through 4D printing.

Liquid tin (Sn) possesses excellent thermophysical properties and demonstrates significant application potential in high-temperature energy systems, nuclear engineering, and advanced manufacturing. In this study, the corrosion behaviors and microstructural mechanisms of Ni-based superalloys (IN625, IN718), austenitic stainless steels (316L, 316Ti, 310S), and titanium materials (CP Ti, Ti-6Al-4V) were systematically evaluated after static exposure to liquid Sn at 500 °C for 500 h. The results indicate that the overall corrosion resistance follows the decreasing order of Ti-6Al-4V ≈ CP Ti > 316Ti > 316L > IN625 > 310S > IN718. Titanium materials exhibit the most outstanding corrosion resistance, with the interaction strictly confined to a highly sluggish and diffusion-controlled interfacial mutual dissolution stage due to the extremely low mutual solubility between Ti and Sn. Austenitic stainless steels generally suffer from the selective leaching of the highly active Ni, accompanied by the formation of porous FeSn2. Ni-based superalloys display divergent corrosion mechanisms. IN625 shifts the corrosion process to diffusion control by forming a continuous Cr- and Mo-rich intermediate layer, whereas IN718 experiences severe bulk dissolution and morphological collapse. This study reveals the critical roles of elemental solubility, diffusion capability, and corrosion layer stability in the evolution of liquid metal corrosion, providing an important theoretical basis for structural material selection and compositional design for high-temperature liquid Sn environments.

Residual stresses inherent in laser directed energy deposition (L-DED) additively manufactured metals are tempting to trigger distortions or even cracks if their levels exceed the materials' yield strength, particularly for thin-walled components with large dimensions. In addition, the complicated thermal history induced by continuous heat input results in heterogeneous microstructures. Herein, a hot pool synergistic method was demonstrated, which is capable of alleviating residual stress and tuning the microstructure in L-DED. By immersing the building part layer-by-layer into heated inert liquid metal, printing on the exposed surface and in-situ preheating/heat dissipation/heat treatment for the immersed part are conducted synchronously at elevated temperatures to reduce the temperature gradient and tailor the texture. As a result, 316L stainless steel parts with less deformation and a homogeneous microstructure are manufactured. The experimental results systematically illustrate that the hot pool synergy is beneficial to the microstructure homogeneity, strength, hardness, wear, and corrosion resistance. This novel method provides a distinct way into the tunability of L-DED in residual stress, microstructure, and performance under extreme manufacturing conditions.

Metallic lattice structures exhibit exceptional multifunctional attributes, including lightweight design, vibration damping, and energy absorption. Although combining additive manufacturing with investment casting provides a cost-effective fabrication route, current approaches are largely limited to low-melting-point metals. This study demonstrates the fabrication of high-melting-point metallic lattice structures via additive manufacturing assisted investment casting, addressing the fundamental challenge of extending this technique to high-melting-point systems (nickel-based alloy and stainless steel), which offer superior mechanical and thermal performance but are hindered by the lack of suitable preform materials. We present a novel quartz glass-based ceramic preform system, engineered through tailored compositional formulation and sintering protocols, which provide a generic solution by meeting the conflicting demands of high-temperature stability and post-casting removability. Orthogonal experimentation coupled with finite element simulations optimized casting parameters (1550 degrees C pouring temperature, 900 degrees C mold preheating), while multiscale characterization (ProCAST, micro-CT, metallography) fundamentally reveals localized shrinkage porosity at nodal junctions-an inherent solidification challenge in such architectures. Validated cellular automaton finite element (CAFE) modeling further enables grain structure prediction, providing mechanistic insights for solidification control. Beyond the successful fabrication of Inconel 713 lattices, this work establishes generic principles for designing high-temperature soluble ceramics and controlling solidification in complex architectures, establishing a scalable platform for highperformance metallic lattice structures and offering a transferable framework applicable to a broad range of high-melting-point alloys.

Alternating viscous and inertial force jetting (AVIFJ) was used to print single-cells and position small numbers of cells precisely. The effect of nozzle size on single-cell encapsulation and droplet spacing ability was tested using astrocytes. Astrocytes were patterned in Matrigel and examined for 7 d after printing to assess viability and their response to being suspended in 3D at low cell density. The results showed AVIFJ had a single-cell printing efficiency around 30% using nozzles with outer diameters (ODs) of 63μm and 96μm at a 300 000 cells ml-1concentration, and 30% for 143µm and 195µm OD nozzles at a 50 000 cells ml-1concentration. Spacing using a 63μm nozzle tests printed droplets with a minimum center-to-center spacing of 199.53 ± 2.52μm on a culture well and cell spacing of 122.23 ± 21.69μm in 3D. Astrocyte viability was 93.60 ± .27% when printed into Matrigel. RNA sequence results showed astrocytes suspended Matrigel upregulated IGFBP3 compared to 2D controls. Results also showed that astrocytes suspended in 3D that contact the culture well react differently than those completely suspended over 4 d. Overall, this study showed the viability of AVIFJ printing for low cell number experiments and differences in astrocyte behavior in 3D suspension compared to 2D.

Strengthening conventional materials through additive manufacturing is generally understood to occur due to rapid cooling in the metallurgical process, which refines the microstructure by producing smaller grain sizes and segregating elements at specific locations. However, the effectiveness of this enhancement mechanism for increasing strength or elongation of parts depends significantly on the nature of the material. For example, austenitic 316L stainless steel fabricated by laser powder bed fusion exhibits superior ductility but struggles to improve its strength. In order to explore the contribution of grain scales and solute segregation in the strengthening of rapid solidification microstructures during additive manufacturing, we investigate an austenitic 316L stainless steel micro-alloyed with Nb and Ti. The austenitic stainless steel is strengthened through grain size refinement and the presence of dislocation cell boundaries enriched with Nb/Cr phases, leading to yield and tensile strengths exceeding 0.8 GPa and 1.1 GPa, respectively. Its strength exceeds that of most current additively manufactured austenitic stainless steels. The strong ferrite-forming components (Nb and Ti) contribute significantly to the microstructural refinement of austenitic stainless steels, with the average grain size decreased by 65.4% compared to austenitic 316L stainless steel. Additionally, the fine grains exhibit predominantly high-angle grain boundaries, and the elevated density of solute segregation in these regions plays a crucial role in contributing to exceptional strength of materials.

The layer-by-layer powder bed additive manufacturing approach, which encapsulates the workpiece in powder during processing, imposes limitations on the integration of in-situ field assistance and enhances production costs. In this work, a novel laser powder bed fusion has been proposed in which the layer-wise accumulated powder bed is replaced by a thin powder layer floating on the liquid Sn. Such a liquid-metal-assisted laser powder bed fusion presents unique advantages: the characteristic thermal history of deposited materials due to high thermal conductivity and fluidity of liquid metals provides greater possibilities for microstructure modulation; the recyclable liquid metal also reduces the need for powder in the forming cylinder and reduces the number of times the powder is reused. Based on the normalized process diagram of liquid-metal-assisted laser powder bed fusion, forming experiments were carried out on the austenitic stainless steels, and the mechanisms underlying the regulation of fine-grain regions were investigated, along with an analysis of the microstructure of this region. Results indicated that the high cooling rate during liquid-metal-assisted laser powder bed fusion led to a finer microstructure and a heterogeneous grain structure ranging from submicron to micron scales in the austenitic stainless steels. The formed heterogeneous austenitic steel exhibits a yield strength surpassing 1.1 GPa and a tensile strength of 1.5 GPa, while retaining an average uniform elongation of 7 %. The in-situ heat treatment principles using liquid metal demonstrated in this work have significant applicability across various additive manufacturing processes and precipitation-hardening alloys.

This study elucidated the microstructure-tensile property evolution of TiAl alloys through synergistic modulation of scanning speed and beam current. As scanning speed and beam current increased, coarse gamma bond-like phases transited into refined alpha(2)/gamma lamellar colonies with preferential 0 degrees/45 degrees orientations relative to the building direction, accompanied by increased phase fractions of alpha(2) (0.194 % -> 0.388 %) and B2 (0 % -> 0.87 %). Meanwhile, at room temperature, the tensile strength increased to similar to 650 MPa due to the enhanced refinement of lamellar colonies, while the elongation decreased owing to the presence of brittle B2 phase, with the fracture mode characterized by quasi-cleavage fracture. At 700 degrees C, the facture elongation rose, owing to the high toughness of B2 phase and the increased activity of slip-twinning in TiAl alloys. The tensile strength remained similar to that at room temperature, with the fracture mode being predominantly intergranular. Furthermore, the specimen with gamma bond-like phases exhibited significant differences in elongation between the directions parallel and perpendicular to the building direction, demonstrating anisotropy. These findings establish an integrated process-microstructure-property optimization strategy for designing advanced TiAl alloys in aerospace directional-load components, particularly addressing performance requirements under complex thermo-mechanical environments.

Diabetes is a significant global metabolic disease. Current treatments, including islet or pancreas transplantation and insulin therapy, are limited by donor shortages and suboptimal glycemic control. Islet organoids, three-dimensional (3D) cell aggregates that mimic pancreatic islets, offer a powerful tool for diabetes research, drug screening, and transplantation therapies. However, challenges remain in engineering methods for the scalable preparation of human islet organoids (hIOs) with homogeneous consistency and controllable incorporation of vascular elements. In this study, we developed a novel bioengineering approach for the stable production of human islet tissue models with vascular elements using a combination of 3D bioprinting-based organoid co-culture and cell self-assembly principles. Human adipose-derived mesenchymal stem cells were differentiated into massive and uniform human islet (3-like cell aggregates (hICAs) using an off-the-shelf polydimethylsiloxane user-defined micropatterning platform system. A tri-module thermal-controlled bioprinting process employing a gelatin-alginate-Matrigel bioink was used for the 3D bioprinting of hICAs and human umbilical vein endothelial cells (HUVECs). Compared with bioprinted hICAs alone, co-bioprinted and co-cultured hICAs and HUVECs more effectively recapitulated the morphogenesis of human islet development, significantly upregulated the expression of pancreatic islet-and endothelial cell-related markers, and enhanced islet function, namely glucose-stimulated insulin secretion. Thus, the self-assembly of hICAs and HUVECs to form hIOs with vascular elements mimics natural human pancreatic islets and may promote functional maturity. Our method provides a scalable platform for generating vascularized aggregation-based tissue models, supporting studies of pancreatic development and diabetes therapy.

The addition of nano reinforcement particles to improve the mechanical properties of nickel-based superalloys in additive manufacturing has become a current research focus. This paper systematically investigates the effects of adding 1.0 wt% TiC nanoparticles on the microstructure and tensile properties of nickel-based superalloy (IN738LC) prepared by electron beam powder bed fusion (EB-PBF). The results show that the adding of TiC nanoparticles promotes the nucleation of new grains while inhibiting the growth of the original grains, reducing the grain width from 82.09 mu m to 28.55 mu m. After the addition of TiC, the average size of the secondary gamma ' phase decreased by 73.2 %, while the average size of the primary gamma ' phase increased by 114.2 %, and the overall amount of gamma ' phase increased by 80.6 %. In addition, the average size of MC carbides increased by 17.16 %, and their quantity increased by 96.2 %. At room temperature, the ultimate tensile strength and elongation at fracture of the composite (1.0 wt% TiC/IN738LC) improved by 23 % and 77 %, respectively. Post-tensile testing, the composite exhibited more and larger dimples, with more carbides within the dimples, thus enhancing the alloy's ductility. The strengthening mechanism of the primary gamma ' phase mainly relies on dislocation pile-up and bypassing, improving the material's strength; the secondary gamma ' phase primarily enhances ductility through dislocation cutting. MC carbides cause more dislocation pile-up, further improving the alloy's resistance to deformation. This paper provides new insights for the development of high-performance nickel-based superalloys.

Support-free building at low overhang angles (small angles to the horizontal) is crucial for the additive manufacturing of intricate TiAl components in the aerospace industry. This study proposes an adaptive up-skin/ down-skin surface area division method and scanning strategy, achieving support-free building of Ti-48Al-2Cr2Nb thin-walled structures with overhang angles as low as 15 degrees via electron beam powder bed fusion. The surface quality, microstructure, and room temperature mechanical properties at different inclination angles are then explored. The results show that variations in building processes across different areas directly affect the element distribution in TiAl alloys, leading to significant microstructural differences. The microstructure of the tilted, support-free thin-walled structures is more uniform, effectively suppressing the formation of "gamma-bands." The lowangle, support-free sample has a near lamellar (NL) structure with thinner gamma-lamellar (gamma L) widths. Interface dislocations, deformed nanotwins, and twin intersections are observed in gamma L. The formation of deformation twins and twin intersections enhances the mechanical properties of TiAl alloys. This study demonstrates the supportfree building of TiAl overhanging thin-walled components and provides insights into how overhang angles affect the microstructure and mechanical properties.

Relatively low density, columnar crystal structure and cracks are always the inevitable hurdles in achieving excellent mechanical performance for tungsten (W) or tungsten alloys manufactured by laser powder bed fusion (LPBF) process. In this work, HfC particles were introduced to tungsten (W) to investigate their influence on cracking inhibition and mechanical properties of W alloys. Particularly, possible reactions and evolution of HfC particles during the LPBF process were analyzed thermodynamically. It was found that Hf and C, decomposed from HfC, would enter into W lattice to form substitution solid solution and reacted with W to form tungsten carbides during the cooling process, acting as the wall of cellular structure. Meanwhile, the added micron-sized HfC particles went through melting, re-solidification to regenerate during the LPBF process. Microstructure examination indicated that the crystallographic orientation relationship between re-generated nano-sized HfC nanoparticles and W matrix was (200)(HfC) // (110)(W) and [0 (1) over bar1](HfC) // [001](W) due to the small lattice mismatch and low interface energy between them. Mitigated thermal stress and uniformly dispersed carbide particles not only suppressed cracking but also refined the grains from 47.0 mu m to 34.6 mu m and altered columnar crystal structure with weakened <111>// BD texture. Together with solid solution strengthening, the maximum compressive strength of W-HfC alloys reached 1832 MPa. The elucidation about the evolution of carbide particles during the LPBF process may provide an applicable strategy for a reasonable carbide strengthening phase for W alloys based on lattice matching during laser additive manufacturing process.