Bone regeneration requires biomaterials capable of combining favorable biological properties, structural stability and controlled architecture to mimic native bone tissue. In this study, composite inks based on gelatin type B (10% w/v), alginate (0.75% w/v) and sol-gel derived silica microspheres were developed for extrusion-based 3D printing of scaffolds for bone regeneration. Silica microspheres with diameters of 50-100µm were synthesized through a water-in-oil emulsion method and incorporated into polymeric matrices to improve filament formation and scaffold stability. Composite fibers were successfully fabricated and optimized at an extrusion flow rate of 25mL/h, generating fiber diameters suitable for bone scaffold architectures. Increasing silica microsphere content up to a certain threshold reduced fiber swelling and enhanced filament support ability, decreased water uptake and improved compressive strength, while maintaining organized macroporous and interconnected architectures after 3D printing and freeze-drying. In addition, silica microspheres were homogeneously distributed within the fibers. In vitro studies using rat bone marrow mesenchymal stem cells demonstrated scaffold biocompatibility and enhanced cell proliferation after 14 days with increasing microsphere content. Overall, these results demonstrate that silica microsphere-reinforced gelatin-alginate composite inks represent a promising strategy for the fabrication of biocompatible and customizable scaffolds for bone tissue engineering.
Reliable fast charging of sodium-ion batteries is constrained by heterogeneous transport, interfacial degradation, thermal accumulation, and mechanically driven failure in hard-carbon anodes. Here, a two-dimensional microstructure-informed multiphysics framework is developed to quantify the coupled degradation pathways governing porous hard-carbon electrodes under C/20–5C charging. The model integrates sodium-ion transport, electronic conduction, Butler–Volmer interfacial kinetics, adsorption–insertion–pore-filling storage, SEI growth, heat generation, and sodiation-induced stress within spatially heterogeneous electrodes representing different degrees of carbon structural ordering. The results reveal a critical transition above 1C, where capacity retention decreases from 80.8% at 1C to 63.4% at 2C and 36.0% at 5C, accompanied by a nonlinear rise in polarization. Spatially resolved analysis shows that fast charging amplifies local current density, accelerates SEI thickening, and promotes thermal and mechanical localization; the current localization factor increases from 1.37 at 1C to 2.91 at 5C, while the maximum temperature rise reaches 18.4K. The maximum Von Mises stress and hard-carbon degradation index identify 2C–5C operation as degradation-prone despite partial capacity accessibility. Experimental validation against capacity, interfacial resistance, SEI thickness, and temperature rise confirms predictive accuracy. This study establishes localized degradation descriptors for designing fast-charge-compatible hard-carbon anodes with improved transport uniformity and interfacial robustness.
The initial curing temperature strongly influences the volume stability of alkali-activated binders, yet the underlying structure-property relationship in metakaolin-slag systems remains insufficiently understood. In this study, alkali-activated metakaolin-slag binders were initially cured at 10, 20, 30, 40, and 50 °C for 12h and investigated through shrinkage and moisture-loss measurements, pore-solution analysis, determination of the reaction degrees of metakaolin and slag, XRD, TGA, MIP, SEM and BSE–EDS analysis, and nanoindentation. Increasing the initial curing temperature from 10 to 40 °C reduced the 28-d shrinkage from 0.129% to 0.055% and decreased moisture loss from 2.01% to 1.15%. Temperature elevation accelerated the early depletion of dissolved Al and Si and increased the 1-d reaction degrees of metakaolin and slag. However, from 1 to 28 d, the increases in the reaction degrees of both precursors decreased with increasing initial curing temperature. The more sustained precursor conversion in the low-temperature groups was accompanied by greater subsequent shrinkage. Moderate initial curing temperatures promoted earlier pore filling and increased the effective gel modulus at 1 d from 9.20GPa at 10 °C to 11.54 and 11.33GPa at 30 and 40 °C, respectively. Under the 10 °C condition, continued pore refinement and greater moisture loss caused desaturation to extend into finer pores, with the critical pore diameter decreasing to 36.4 μm at 28 d. By contrast, curing at 50 °C resulted in rapid early precursor conversion but limited subsequent pore refinement and macroscopic cracking. The results show that volume stability depends on the development of precursor reaction and its coupled effects on moisture loss, pore evolution, and the micromechanical properties of the reaction-product matrix.
The annual volume of postconsumer plastic products is continuously increasing, while recycling remains limited because the separation of materials is difficult. A previous study investigated the separation of polymers in cotton/polyester (PET; polyethylene terephthalate) blended fabrics in the polymer state using a hydrothermal treatment. However, since PET generally undergoes hydrolysis during hydrothermal treatment, it is essential in this method to separate PET while minimizing degradation. This study aimed to minimize and control the degradation of PET during the separation of cotton/polyester blends. A semiflow hydrothermal treatment apparatus was designed to facilitate rapid contact between prepared hot water and the sample, reducing the heating and cooling times to achieve the instantaneous melting of PET. As a result, PET was successfully separated from the fabrics obtained at temperatures above 207°C, while the treated fabrics retained their original structure. The characteristics of the separated PET were evaluated, and gel permeation chromatography analysis revealed that separated PET retained up to 55% of number‑average molecular weight (Mn) compared with untreated PET, indicating the successful separation of PET with minimized degradation. Furthermore, by applying the severity factor, which is commonly used as a time–temperature parameter that reflects nonisothermal, nonisokinetic hydrothermal treatment conditions, a linear correlation between the severity factor and the Mn of separated PET was established. These results demonstrate that the as-developed apparatus enables effective polymer separation with minimized degradation for mechanical recycling and offers the potential for controlling molecular weight based on the severity factor.
Accurate prediction of the coupled thermal and hydraulic behaviors of nanofluids in heat exchangers potentially avoids repetitive experimental testing. Thus, the present study aimed to develop a data-driven surrogate modeling framework capable of predicting the thermal and hydraulic behaviors of MgO and MgO-CuO / Transformer Oil nanofluids in a plate-fin heat exchanger in a temperature range of 30–70 °C. We digitized literature-sourced data using WebPlotDigitizer and reconstructed heat transfer and flow-rate experimental curves with piecewise cubic Hermite interpolation, maintaining monotonic behavior in the time dimension. Four independent forward feedforward 2–5–1 architecture artificial multilayer perceptrons, trained using the Levenberg-Marquardt technique, predicted overall and convective heat transfer coefficients, Reynolds number, and pumping power. Reliability was demonstrated through 30 individual runs, 10-fold cross-validation, repeat internal holdout, grouped anchor holdout, and boundary stress tests. The results were compared with support vector regression with radial basis function (SVR-RBF), random forest regression (RFR), and a multilayer perceptron trained via stochastic gradient descent with momentum. The overall percentage error (mean absolute error, MAE) for the four parameters for the Levenberg-Marquardt approach was 2.363, 0.433, 1.055, and 0.280%; the mean coefficient of determination (R2) ranged from 0.97838 to 0.99789. No approach dominated overall; alternative models had minimal training error for individual output variables, while the Levenberg-Marquardt framework produced the most evenly distributed results and the lowest variability among the four coupled responses. Under boundary evaluation, this framework captured the highest overall efficiency (lowest root mean square errors for both the convective heat transfer coefficient, 25.491 W/m²·K, and the Reynolds number, 21.653). Under the given boundary conditions, changes in oil viscosity due to heat input altered hydraulic flow-rate behavior, while adding nanoparticles changed thermal efficiency and the pumping energy cost ratio. By integrating multiple response models, comparing algorithms, and using a boundary-validation approach, the constructed framework may provide very fast intra-domain filtering of the thermo-hydraulic design. Nevertheless, its usability is limited to the described test conditions for the mentioned fluid and exchanger type.
Crack-templated Ag networks are promising for flexible electrodes, but their conductance is strongly governed by stochastic morphology. Here, we establish an image-based structure–property framework that combines microscopy quantification, cGAN-based descriptor augmentation, and graph-based equivalent-circuit modeling. From 1,152 optical micrographs, we obtained 2,952 processed images using Gaussian filtering and adaptive thresholding and extracted four key morphological descriptors—edge density (ED), node-to-node distance (L), branch width (W), and fractal dimension (FD). The cGAN generated over 10,000 architectures to densely populate the morphology space, and their conductance was evaluated using Kirchhoff’s laws on skeletonized topologies. Multivariate analysis identified a unique scaling parameter, χ=W×L/FD2, exhibiting strong linear correlations with branch count (R² = 0.9238) and conductance (R² = 0.964). This χ-based scaling law provides a direct, quantitative design criterion by mathematically decoupling the topological efficiency of conductive pathways from raw material loading. To demonstrate its practical utility, we performed two distinct structural optimizations. One achieved a 125.9% conductance increase (a 2.26-fold enhancement) despite an 8.0% reduction in edge density, whereas the other successfully maintained baseline conductance with 22.8% less edge density. By establishing χ as a compact parameter that clearly defines the morphology–conductance relationship, this framework allows engineers to deterministically maximize electrical performance while strictly minimizing noble-metal consumption. Ultimately, this geometry-driven paradigm addresses critical resource constraints in large-scale manufacturing, offering an economically viable pathway for next-generation flexible optoelectronics.
Monoclinic vanadium dioxide (VO2(M)) is a representative thermochromic material whose practical application requires precise control of its crystalline phase formation and crystallinity under hydrothermal conditions. However, the phase formation behavior of the VO2 polymorphs remains difficult to interpret due to strong parameter coupling and phase coexistence.In this study, the crystal growth and phase formation behavior of VO2 were systematically investigated using microwave-assisted hydrothermal synthesis and an L9 orthogonal experimental design. The effects of the oxalic acid ratio, precursor concentration, reaction temperature, and reaction time on phase formation were evaluated within a compact experimental space. Because phase coexistence complicates interpretation of mixed-phase X-ray diffraction (XRD) datasets, non-negative matrix factorization with clustering (NMFk) was employed to extract physically interpretable phase-related diffraction components.An NMF-derived descriptor associated with the VO2(M) phase was used as a semi-quantitative descriptor of the VO2(M)-related diffraction contribution. The descriptor showed a consistent ordering with the latent heat of the metal–insulator transition measured by differential scanning calorimetry. Within the investigated design space, statistical analysis identified precursor concentration as the factor producing the largest variation in the VO2(M)-related descriptor, followed by reaction temperature and time. Combined analysis of the phase-selection trends and precursor-concentration series revealed a concentration-dependent trade-off between VO2(M)-related structural development and phase selectivity, where dilution promotes crystallinity development of VO2(M) but also increases the contribution of competing VO2(A). The results further suggest that hydrothermal synthesis parameters influence not only phase selectivity but also the extent of polymorph evolution achieved during synthesis. These findings clarify how precursor concentration mediates the competing development of VO2(M) crystallinity and VO2(A) formation, thereby linking dilution-induced crystal growth with polymorph competition in hydrothermal VO2 synthesis.
Black phosphorus quantum dots (BPQDs) have emerged as an important class of zero-dimensional quantum materials that combine the anisotropic electronic structure of black phosphorus with pronounced quantum confinement effects. Their size-dependent optical, electronic, and physicochemical properties have stimulated extensive research in nanoelectronics, sensing, photocatalysis, and biomedicine. Despite significant progress, the practical implementation of BPQDs remains constrained by limited control over structure–property relationships, insufficient stability under environmental conditions, and the absence of unified engineering principles. This review critically examines recent advances in BPQD synthesis, structural engineering, quantum confinement, and advanced characterization, with particular emphasis on the mechanisms governing degradation, surface reactivity, defect evolution, and stability. Rather than summarizing existing studies individually, the review establishes an integrated framework connecting synthetic strategies, structural characteristics, stability mechanisms, and functional performance. Current challenges associated with scalable production, standardized characterization, and long-term reliability are critically evaluated, and future perspectives are discussed in the context of predictive design, interface engineering, and stability-oriented material development. This integrated perspective provides practical guidance for advancing BPQDs from laboratory-scale nanomaterials toward reliable quantum platforms for next-generation technologies.
Effective prediction of crystallographic texture evolution during plastic deformation is essential for designing metallic materials with tailored mechanical properties. In this study, a combined experimental–computational framework was developed to investigate texture evolution in AA1050 aluminum wires during drawing. First, a single-pass drawing process (10mm → 9mm) was simulated using the crystal plasticity finite element method (CPFEM) and validated through comparison with the EBSD measurements. Subsequently, the validated CPFEM model was employed to generate crystallographic orientation data at multiple deformation levels during a three-pass drawing process (10mm → 6.8mm), which were used to construct a dataset for machine-learning analysis. The CPFEM–EBSD results revealed a progressive strengthening of the crystallographic fiber texture, characterized by the development of a duplex [111]/[100] texture due to deformation-induced grain rotation and slip activity. A comparative evaluation of the machine-learning models showed that the ANN exhibited limited capability in predicting texture evolution, whereas the RANSAC regression model provided more accurate and robust predictions. Comparison with EBSD measurements further confirmed that the RANSAC-based approach more reliably reproduces the experimentally observed texture evolution during wire drawing.
Polymethyl methacrylate (PMMA) is widely used in automotive, medical, and optical applications owing to its low cost and good processability, but its inherent brittleness limits its performance under cyclic loading. We reinforce PMMA with unidirectional glass fabrics in three layup configurations—single-layer [0°]1, double-layer [0°]2, and cross-ply [0°/90°]1 and systematically evaluate their quasi-static tensile and tension-tension fatigue behaviors. We demonstrated that the double-layer [0°]2 configuration delivers the highest tensile strength of 53.93MPa, a 126% increase over neat PMMA, and achieves a fatigue limit stress of 10.74MPa at 106 cycles, compared with near-zero fatigue resistance of the unreinforced matrix. Using a stiffness-based equivalent Paris-type damage model, we identify a stress-level-dependent fatigue mechanism: at high stress levels, interfacial debonding dominates and accelerates failure, whereas at low stress levels, the aligned fibres effectively transfer load, suppress crack propagation, and prolong fatigue life. Notably, the single-layer [0°]1 composite exhibits the highest Paris exponent, 8.99, indicating strong sensitivity to interfacial damage, while the double-layer [0°]₂ composite has the lowest coefficient, 2.79×10⁻⁶, confirming its superior resistance to cumulative damage. This study shows that the fatigue behaviour of fibre-reinforced thermoplastic composites is strongly governed by layup configuration.
Electrospinning is a well-established method for producing nanofibres. However, it relies on solution pumping systems. In this study, we propose a novel electrospinning strategy based on acoustic levitation that enables contactless droplet handling and uniform particle embedding during fibre fabrication, as a preliminary proof-of-concept. In this setup, a standing acoustic wave levitates the polymer droplet in mid-air, while a wire applied with high voltage periodically crosses the levitated droplet to cover a thin solution layer on its surface. Once high voltage is applied, fibre production initiates. To validate uniform embedding, hydroxyapatite (HA) particles synthesised from eggshells were incorporated into polyvinyl alcohol (PVOH) and successfully electrospun with good dispersion. To demonstrate contactless bioactive material processing, bacteriophage (phage) was mixed with fish gelatin solution and fabricated into an antibacterial wound dressing, with phage activity remaining detectable after storage for up to 14 days and showing high cytocompatibility. These findings demonstrate the potential of acoustic levitation to assist electrospinning, suggesting its applicability in biomedical applications requiring reduced surface contact and gentle processing of sensitive biologics.
Rapid and stable osseointegration is critical for the success of titanium implants, particularly in low-density bone. Here, TiO2 nanotube arrays were fabricated by constant-voltage anodization and sequentially functionalized with acrylic acid (AA) and 2,2′-oxybis(ethylamine) (AEEA). AA grafting introduced surface carboxyl groups, and subsequent AEEA coupling formed amide bonds while exposing terminal amine groups, yielding a superhydrophilic interface that combines nanotopography with reactive surface chemistry. SEM, XPS, and FTIR confirmed the nanotube morphology and the stepwise grafting. Biological performance was evaluated in MC3T3-E1 cells and rat bone marrow mesenchymal stem cells, and in a rat femoral implantation model. The AEEA-modified surface promoted cell adhesion and spreading, enhanced osteogenic differentiation and matrix mineralization in both cell models, and improved peri-implant bone formation in vivo. Sequential AA/AEEA grafting therefore provides a drug-free strategy that integrates nanotopography, wettability, and amide/amine surface chemistry to improve the osteogenic performance of titanium implants.
Composite cement has emerged as a viable low-clinker alternative to conventional cement systems; however, its holistic performance in concrete, particularly in terms of durability and sustainability, remains insufficiently documented. This study investigates the fresh, mechanical, transport, durability, and environmental performance of composite cement concrete in comparison with OPC, PPC, and PSC concretes. Concrete mixes were prepared with composite cement at water–cement ratios of 0.40, 0.45, and 0.50, while reference mixes were designed with comparable workability. Fresh properties showed controlled rheological behavior, with slump ranging from 60 to 100mm and consistent correlations observed among slump, compaction factor, Kelly ball, and yield stress. Composite cement concretes achieved superior mechanical performance, with compressive strength reaching 44.6MPa at 28 days, representing an improvement of about 10–15% over conventional cement concretes. Splitting tensile, flexural strength, and elastic modulus increased by 12–20%, confirming enhanced crack resistance and stiffness. Transport and durability indicators demonstrated significant pore refinement, with water permeability reducing to about 1.4 × 10⁻¹⁰ m/s, RCPT charge passed falling below 300 coulombs, and surface resistivity exceeding 140 kΩ-cm at 90 days, indicating very low corrosion risk. Under aggressive environments, composite cement concretes exhibited lower mass loss and retained more than 89% and 93% of their original compressive strength after acid and sulphate exposure, respectively. Life cycle assessment revealed reductions of 10–12% in embodied energy and 15–17% in global warming potential compared to OPC concrete.
Controlled processing strategies can influence the physicochemical and functional characteristics of citron peel pectin. This study compared pectin obtained through microwave drying followed by microwave-assisted extraction (MWD–MAE) with that produced by conventional drying followed by conventional extraction (CD–CE) to investigate processing-route-related differences in composition, molecular characteristics, thermal behavior, and rheological properties. MWD–MAE pectin exhibited a higher apparent weight-average molecular weight (Mw) than CD–CE pectin (388.7 ± 1.15 vs. 349.3 ± 2.10kDa; p < 0.001) and a higher galacturonic acid content (89.09 ± 0.04% w/w), accompanied by a lower Rha/GalA ratio, suggesting differences in the relative abundance of GalA- and rhamnose-associated structural features. FTIR and ¹H NMR analyses confirmed the characteristic chemical features of pectin and indicated processing-related differences in esterification-associated characteristics. Thermogravimetric analysis revealed distinct thermal degradation behaviors between the two pectin samples, while rheological measurements showed that MWD–MAE pectin generally exhibited higher apparent viscosity and viscoelastic moduli, with G′ remaining above G″ across the investigated frequency range. Collectively, the compositional, molecular-weight, spectroscopic, thermal, and rheological results indicate that the two integrated processing routes were associated with distinct physicochemical and functional characteristics of the recovered pectin. These findings support the potential of MWD–MAE-derived citron peel pectin for future hydrocolloid and formulation applications.
The demand for weight reduction in elevating platforms has become increasingly critical due to legal transport constraints and operational efficiency requirements. Current structural and safety components, primarily fabricated from metallic materials, present limitations in terms of maneuverability, labor requirements, and energy consumption. This study addresses the design and development of composite and metal-composite hybrid components to achieve significant weight reductions, targeting 25% in structural members, without compromising mechanical integrity or safety standards. The prototype fabrication ultimately achieved a weight reduction of approximately 40% in the composite floor panel, the primary redesigned element, corresponding to an overall platform mass reduction of 26.1% across all redesigned components (Table 3), exceeding the initial design target for these elements. A key objective is the implementation of a metal-composite hybridisation system capable of withstanding the structural loads encountered during platform operation. The research encompasses material selection, mechanical characterization, and structural optimization, with particular focus on the behavior and reliability of critical metal-composite joints under load. The study demonstrates the potential of advanced composites to replace conventional metal parts in elevating platforms, contributing to reduced assembly time, improved energy efficiency, and enhanced safety, thereby supporting a broader industrial shift toward lightweight engineering solutions.
This study demonstrates a rigorous numerical simulation that maps out the parametric sensitivity analysis, mesh grid independence and structural convergence verification of magnetohydrodynamic (MHD) Casson Hybrid Nanofluid (TiO2+Ag-NPs/WEG) flow and heat transfer over a rotating porous stretching surface. The fluid model consists of a 50:50 water and ethylene glycol solution with the addition of titanium dioxide and silver nanoparticles that are widely used for biosensing, medical diagnostics, and photocatalytic devices. The mathematical model is capable of accounting for all the above effects in a comprehensive manner, such as Joule heating, Brownian motion, thermophoresis, space-dependent heat source and exponential activation energy of Arrhenius. The transformed boundary layer ODE's are solved by the adaptive three-step Lobatto IIIa finite-difference formula, which is embedded in the bvp4c collocation solver in MATLAB. Precise grid independence tests demonstrate that the maximum local residual error is always within a convergence tolerance of 10-6 and precisely bounded by the relative error of 10-7 and absolute error of 10-9 when the number of nodes in the system is increased from N = 40 to N = 200\ nodes. The quantitative sensitivity analysis indices computed using response derivatives identify precisely the percentage margins of influence of the competing operational parameters for surface shear stress and wall heat flux. In addition, two-dimensional internal flow streamlines are plotted to trace the trajectory bending of the internal flow which shows the zones of fluid deceleration and cross flow splitting’s of flow trajectories which are rotational. The parametric evaluations show that the influence of the different porosities of the surfaces and magnetic fields restrict the primary flow velocity. The velocity fields enhance with increasing Casson parameters and sheet rotation quantities, but decrease with the inclined magnetic field. In terms of percentage, the local heat transfer rate reduces by up to 12.80% when the magnetic inclination is changed from 20° to 80° while it increases by up to 70.25% and 114.67% upon the increase of the thermal Biot number from 2.0 to 8.0 and the heat source parameter from 0.4 to 1.2, respectively.
Hexavalent chromium Cr(VI) is considered a highly toxic carcinogenic and injurious pollutant frequently encountered in industrial wastewater, imposing environmental and public health challenges. Among different treatment approaches, chitosan-based hydrogels (CBHs) have emerged as a highly promising and effective class of adsorbents, owing to their superior adsorption capacity, rich functional groups, and customizable physicochemical properties. Recent advancements in CBH have gone beyond the traditional single-network gel towards multifunctional entity that combine easy separation, strong mechanical integration and responsive behaviour. Magnetic variants offer quick recovery facilitating redox-assisted chromium reduction. Crosslinked CBHs merged with covalent bridges exhibit higher structural stability with high uptake. Besides, luminescent formulations provide additional benefit of in-situ Cr(VI) recognition, though their long-term resilience in lower pH is still being optimized. Apart from this, incorporation of nano-fillers promotes surface accessibility alongside efficient electron-transfer, while bio-hybrid design merged with chitosan and other polymers improves mechanical robustness with scalable production. Architected hydrogel produced by advanced printing, stimuli-responsive networks, and other catalytic elements lead toward next-generation CBH systems with adjustable selectivity, on-demand regeneration, and real-time performance feedback. This review includes the process, progress, challenges, and prospects of CBH technologies offering a sustainable, high-efficiency system for Cr(VI) removal in complex wastewater environments.
End-of-life tyre rubber is a persistent waste material that can be reused in cement-based composites; however, its hydrophobic surface and weak bonding with cement matrix often reduce mechanical performance and durability. This study investigates how two types of tyre rubber waste, namely fine devulcanized rubber particles and rubber fibres, affect the properties of fine-grained concrete. Fine-grained concrete mixtures were prepared by replacing natural sand with tyre rubber at different contents, while selected rubber particles were surface-modified using a styrene-acrylic coating and waste metakaolin in order to improve the rubber–cement matrix interface. The effects of tyre rubber incorporation on density, porosity, water absorption, predicted resistance to freeze-thaw cycles, sound absorption coefficient, and the leaching of potentially harmful elements were evaluated. The results showed that the surface treatment significantly improved the quality of the interfacial transition zone (ITZ). Rubber surface coating proved to be an effective modification method, resulting in lower water absorption and open porosity, as well as higher flexural strength and predicted freeze–thaw resistance, compared with concrete containing uncoated rubber. The mixture containing 15% fine rubber particles exhibited the highest sound absorption coefficient of 0.46 at 2000 Hz, representing a 39% improvement compared with the reference mixture. Leaching tests confirmed that the concentrations of potentially harmful elements released from the rubberised concrete remained below environmentally significant levels under the investigated conditions. Overall, the results show that tyre rubber can be used to produce lightweight concrete with improved acoustic performance when rubber content and surface treatment are properly optimised. Surface modification with styrene-acrylic binder and waste metakaolin is recommended to improve ITZ quality, reduce water transport and support environmentally acceptable circular construction materials.
Wire Arc Additive Manufacturing (WAAM), a cost-effective fabrication method, has recently been applied to produce bimetallic structures. In this study, a bimetallic structure comprising 20 layers of Martensitic Stainless Steel (MSS) and 20 layers of Mild Steel (MS) was successfully fabricated using WAAM. The macrostructure of the as-built bimetallic structure near the transition zone reveals four distinct regions: the MSS region, the interface, and two MS sub-regions. The microstructure of the manufactured structure was characterized using Scanning Electron Microscopy (SEM), Optical Microscopy (OM), X-ray Diffraction (XRD), and Electron Backscattered Diffraction (EBSD). Mechanical properties of different regions within the bimetallic structure were assessed using nanoindentation and tensile testing. Corrosion resistance was evaluated via potentiodynamic polarization and electrochemical impedance spectroscopy. MSS exhibited both island-shaped and skeletal δ-ferrite dispersed within a martensitic matrix, while the interface exhibited a predominantly martensitic microstructure, with no retained austenite detected in either region. In contrast, MS showed acicular and polygonal ferrite. Tensile testing revealed an ultimate tensile strength of 504 ± 6MPa and a yield strength of 372 ± 5MPa, with fracture occurring in the MS region. Corrosion analysis revealed a gradual decrease in resistance from MSS to MS, attributed to Cr migration from MSS toward the interface, resulting in elemental variations across the gradient.
Understanding the crystal growth process has been a persistent problem in materials science. Although phase-field (PF) simulation can effectively predict solidification behavior and reveal various microstructure formation mechanisms, a novel parameter determination technique is required because of the unreliable parameters used for the simulation. Recently, a data-assimilation-based parameter determination method was proposed to directly determine solid-liquid interface properties using in situ experimental observation data. In this study, we first report that the solid-liquid interfacial properties can be quantitatively determined using a data assimilation technique combined with PF simulations. Further, we demonstrate that interfacial mobility, which is often treated as an adjustable parameter to reproduce microstructure formation, can be determined based on experimental data, including uncertainties. Our findings indicate that effective interfacial mobility, which is often treated as a fitting parameter in PF simulations, can be estimated from experimental observations with quantified uncertainty.
