Structural Materials Research Articles

Radiation damage in He irradiated nanolayered Zr/Nb at different temperatures

Nanolayered Zr/Nb metals are considered promising for advanced nuclear reactors due to their superior resistance to irradiation. In this study, Zr/Nb multilayers were irradiated with 50 keV He+ ions to a fluence of 1 × 1017 ions/cm2 at temperatures of room temperature, 350 °C, and 500 °C to investigate irradiation-induced structural changes. X-ray diffraction (XRD) analysis indicated low-angle shifts of 0.08-0.54° and high-angle shifts of 0.08-0.42° in the irradiated Zr and Nb layers, suggesting tensile and compressive strains, respectively. At 500 °C, the selected-area electron diffraction (SAED) observed a 9.2% lattice expansion in Zr and a 0.13% contraction in Nb. Geometric phase analysis (GPA) revealed varying strain distributions, transitioning from incoherent to coherent interfaces with increasing irradiation damage. Transmission electron microscopy (TEM) identified the presence of He bubbles in the Zr layer as one of the reasons for strain differences. Nanoindentation tests showed an increase at a depth of 150 nm hardness of 0.831 GPa at 500 °C compared to 350 °C. These results are attributed to differences in crystal structure, vacancy dynamics, interfacial effects, and lattice strain influences. Stability of Zr/Nb interfaces after He irradiation was studied. This study provides insights into the radiation behavior of Zr/Nb nanoscale metallic materials, enhancing our understanding of their potential as structural materials in nuclear energy systems.

Structural Material Condition Assessment through Human-in-the-Loop Incremental Semisupervised Learning from Hyperspectral Images

Structural Material Condition Assessment through Human-in-the-Loop Incremental Semisupervised Learning from Hyperspectral Images

Enhanced single-atom cobalt layer in MAX phase for biomass electrooxidation integrated with hydrogen evolution

MAX phases have attracted considerable interest due to their structural diversities and potential applications. More than 150 MAX phases have been synthesized, especially expanding the range of A-site atoms from traditional main group elements to subgroup elements with outer layer d electronic structure. However, the functional applications for MAX phases remain somewhat limited. The A-site elements in MAX phases can amplify their inherent properties, transforming primary structural materials into multifunctional materials. As highly catalytic elements, introducing cobalt into the A-site of MAX phases can reveal surprising catalytic activities. Hence, the MAX phase with single-atom-thick cobalt layers was synthesized via an A-site alloying strategy in this work. The obtained V2(Sn2/3Co1/3)C MAX phase demonstrates efficient electrocatalysis in 5-hydroxymethylfurfural (HMF) oxidation reaction along with hydrogen evolution reaction (HER). In-situ electrochemical studies discover that HMF can prevent the self-reconstruction of MAX phase and oxygen evolution reaction (OER). The overall reaction reaches 94.4 % yield to 2,5-furandicarboxylic acid (FDCA) at 1.60 V. Density functional theory calculations suggest that the Co-Sn bimetallic synergy in the A-site promotes the reaction. This groundbreaking investigation into using MAX phases for biomass upgrading highlights their potential in green chemistry and beyond.

Review of Surface Treatment Technology for Improving Wear Resistance of Magnesium Alloys

Background: As the lightest metal structural material in engineering, magnesium alloy has excellent mechanical properties, such as high specific strength, high specific stiffness, good damping performance, and good machinability. It is widely used in the fields of precision parts, automobiles, aerospace, and military. However, poor friction and wear performance are significant magnesium defects of the alloys, which make its use limited in some areas with high working conditions, so it is essential to improve the wear resistance of the magnesium alloy surface. Objective: The aim of this study was to summarize the technology of improving the wear resistance of magnesium alloy in recent year. The influence of different surface treatment technology for enhancing friction and wear properties was also analyzed, which could provide a reference for related scholars and researchers. Method: In this paper, the literature related to friction and wear properties of magnesium alloys in recent years were reviewed, the principles of various surface treatment technology of magnesium alloys were explained, and the advantages and disadvantages of each technology were analyzed. Results: Based on the literature analyses related to the wear resistance of magnesium alloys, the problems existing in the surface treatment technology for improving the wear resistance of magnesium alloys are summarized, and future development directions are put forward. Conclusion: Among the technologies to improve the wear resistance of magnesium alloys, the combination of various techniques can better meet the working demands. The environmentally friendly and efficient manner has a good prospect for development.

Local element segregation-induced cellular structures and dominant dislocation planar slip enable exceptional strength-ductility synergy in an additively-manufactured CoNiV multicomponent alloy with ageing treatment

We proposed an additively manufactured equiatomic CoNiV multicomponent alloy (MCA) using a conventional laser powder bed fusion (LPBF) method, and an exceptional strength-ductility synergy of the alloy was attained through a simple post-ageing treatment. Pronounced hierarchical microstructures were achieved in our printed alloys, including heterogeneous grain structures, and intragranular cellular structures composed of interior domain with limited dislocations and cell walls led by significant vanadium local segregation. Besides the outstanding mechanical properties at room temperature of 298 K, a giga-pascal yielding strength (> 1.1 GP) and over 40% uniform elongation were attained in the aged specimen deformed at a cryogenic temperature of 77 K, predominating the mechanical properties of many alloys reported in previous works. Such exceptional performance of the aged alloy can be mainly ascribed to considerable local chemical orders (LCOs), aggravated elemental fluctuation in the alloy matrix, and intensified vanadium segregation at walls of intragranular cellular structures which can strongly interact with dislocations. As a result, a planar slip array of dislocations with an extremely high density, namely large numbers of slip bands that can sustain and transfer high strains, dominates the deformation microstructures, thus efficiently strengthening and toughening the aged alloy, especially at a low temperature like 77 K. The above post-ageing strategy is readily and low-costly employed on additively manufactured MCAs with relatively high stacking fault energy (SFE) and proved as a feasible method to produce high-performance structural materials for extreme conditions.

Plastic evolution and phase transition mechanisms in γ-TiAl nano polycrystal by a molecular dynamics simulation

γ-TiAl based alloys are widely regarded as one important high-temperature structural material, however the deformation behaviors are still not clearly clarified. The microscopic plastic deformation and phase transition of γ-TiAl nano polycrystals under compression are investigated by molecular dynamics simulations. The results show that the initial plasticity is dominated by slip of partial dislocations whose continuous formation and secondary slip on the same slip plane result in the generation and disappearance of intrinsic stacking faults (ISFs). At the strain of about 0.2, a continuous structure transformation of “ISF → ESF → TB” is observed, during which the interaction between different ISFs causes the atomic misalignment corresponding to the change in atomic stacking order near ISF. As the compressive strain exceeds 0.2, the FCC-to-BCC phase transition occurs within polycrystals due to the high Mises stress, the high stress level within grains facilitates the expansion of BCC phase from initial FCC phase, and the newly formed BCC phase maintains the atomic-arrangement orderliness of original phase. The interface between FCC and BCC phases obeys the low-energy Kurdjumov-Sachs orientation relationship. This work is helpful for better understanding the atomic-scale deformation behaviors and provides a theoretical guidance for designing high-performance alloy materials.

АДГЕЗИВНАЯ АКТИВНОСТЬ МИКРООРГАНИЗМОВ К СТОМАТОЛОГИЧЕСКИМ МАТЕРИАЛАМ ДЛЯ 3D ПЕЧАТИ И ВАКУУМНОЙ ФОРМОВКИ

Relevance: The adhesive activity of the oral microbiome to new generation materials is the subject of study by the global medical community, and the issue of choosing structural materials is still being discussed in the scientific community and is of a controversial nature. Objective: To study the adhesion of representatives of the oral microbiome to samples of modern dental materials under experimental conditions (in vitro). Materials and methods: Samples of photopolymer resins for 3D printing: Dental Crown LCD, Dental Sand A1-A2, Dental Clear Pro, (n=30), (1-3 groups), thermoforming plates for vacuum forming: EV Gasket Bleaching 080, Bioplast multicolor 3.0*123 mm, Bioplast color 3.0*125 mm (n=30), (groups 4-6); clinical isolates of the microbiome as test strains: Staphylococcus aureus, Streptococcus oralis, Neisseria subflava, Actinomyces oris, Candida albicans (n=5). Research methods: experimental, microbiological, cultural, analytical and statistical. Results: The degree of adhesion of representatives of the oral microbiome to the studied structural materials is in the range from 0 to 4.91 (Ia) and depends on both the species composition of the microbiome and the physico-chemical properties of the materials. The high adhesion index for all microbiota groups was noted for vacuum forming materials (4.91), and the lowest was Dental Crown LCD (0), which makes it possible to recommend it for practical use. Conclusions: The choice of structural material should be made, including taking into account the adhesive activity of the oral microbiome in order to reduce the risk of complications. It is recommended to give preference to materials with a low adhesive activity index.

Ceramic matrix composites for corrosion-resistant next-generation nuclear reactor systems: A conceptual review of enhancements in durability against molten salt attack

Ceramic matrix composites (CMCs) are emerging as a key material class for enhancing corrosion resistance in next-generation nuclear reactor systems, particularly in high-temperature molten salt environments. These environments, critical for advanced nuclear reactors such as molten salt reactors (MSRs), present severe challenges, including aggressive chemical attacks that degrade traditional structural materials over time. This conceptual review explores the development and application of CMCs to improve the durability and corrosion resistance of nuclear reactors exposed to molten salt attacks. CMCs, which consist of ceramic fibers embedded in a ceramic matrix, offer significant advantages, such as high thermal stability, mechanical strength, and improved corrosion resistance compared to conventional materials. This review examines how CMCs can be tailored to withstand harsh operational conditions, with a focus on the selection of ceramic phases, fiber-matrix interactions, and innovative fabrication techniques that enhance their protective capabilities. Key challenges addressed include the optimization of composite design to resist molten salt corrosion, the effects of temperature on the material properties, and the long-term stability of CMCs under extreme conditions. Advances in surface treatments, coatings, and the development of hybrid CMC systems are also discussed, highlighting their potential to further enhance durability. The review outlines the use of advanced characterization techniques, such as high-temperature corrosion testing and in situ microscopy, to evaluate CMC performance in molten salt environments. Additionally, it identifies knowledge gaps in current research, emphasizing the need for long-term studies on CMC behavior under realistic reactor conditions. This review concludes by proposing future research directions and technological advancements required to integrate CMCs into next-generation nuclear reactor designs, aiming to improve system reliability and operational safety.

Strengthening Effect Evaluation of Developed Stiff-Type Polyurea Sprayed on Masonry Beam Surface Under Static Loading in Experimental and Numerical Tests

Recently, deteriorated masonry structures aged over 30 years have shown serious structural problems. Simple and rapid maintenance plans are urgently needed for aging masonry structures. Polyurea (PU) is an effective retrofitting material for aging structures due to its easy spray application. This process saves time, reduces costs, and allows the structure to remain in use during retrofitting. However, a general PU is not suitable for retrofitting aged masonry and concrete structures due to its low stiffness. In this study, stiff-type polyurea (STPU) was selected as the reinforcement material for masonry structures. It was developed by modifying the chemical mix of general PU to improve stiffness. To evaluate the strengthening effect of STPU on masonry members under static loading, tests were conducted. The flexural load capacity of masonry beams with STPU-sprayed surfaces was assessed. Three different types of STPU applications were used to select the most efficient strengthening method. Reinforcing masonry structures with STPU allows brittle failure modes to achieve ductile behavior. This improves their structural performance under lateral stresses. The experimental data were used to calibrate FEM models for simulation. These models can be used for future parametric studies and masonry structural design.

Endoxylanase Immobilized Nanoporous Silica for the Production of Xylooligosaccharides: Equilibrium Kinetics, Thermodynamic Studies, and Enzyme Characteristics

AbstractNanoporous structured silica materials, namely f‐SiO2, SBA‐15, IITM‐41, and MCM‐41 were employed as the matrices for immobilizing endoxylanase by adsorption method. The equilibrium kinetics, activation energy, and thermodynamic parameters associated with endoxylanase adsorption were investigated. Our findings revealed a two‐phase adsorption mechanism: an initial phase featuring rapid adsorption rates, succeeded by a slower phase wherein adsorption gradually progressed until equilibrium was attained. Analysis of the adsorption kinetic data indicated a better fit with the pseudo‐second‐order model, suggesting chemisorption and highlighting its temperature dependency. The calculated activation energy (Ea) values fell within the range of physisorption, indicating the involvement of both types of adsorption processes. Thermodynamic assessments confirmed that the adsorption reactions were spontaneous, feasible, and endothermic. Notably, the immobilization process did not change the optimum pH of the enzyme, while the optimum temperature shifted slightly. Furthermore, immobilized enzymes show a higher reaction rate (Vmax) than the soluble XynC. All immobilized xylanases produced xylobiose (X2) to xylohexose (X6) by hydrolyzing the xylan substrate. Recycling studies showed that up to 80 % of the yield was retained after seven cycles of reuse. Our study demonstrates the potential of nanostructured silica as an effective immobilization matrix for enzymes of industrial significance.

Spectroscopy-Guided Discovery of Three-Dimensional Structures of Disordered Materials with Diffusion Models

Abstract Spectroscopy techniques such as X-ray absorption near edge structure (XANES) provide valuable insights into the atomic structures of materials, yet the inverse prediction of precise structures from spectroscopic data remains a formidable challenge. In this study, we introduce a framework that combines generative artificial intelligence (AI) models with XANES spectroscopy to predict three-dimensional atomic structures of disordered systems, using amorphous carbon ($a$-C) as a model system. In this work, we introduce a new framework based on the diffusion model, a recent generative machine learning method, to predict 3D structures of disordered materials from a target property.For demonstration, we apply the model to identify the atomic structures of $a$-C as a representative material system from the target XANES spectra. We show that conditional generation guided by XANES spectra reproduces key features of the target structures. Furthermore, we show that our model can steer the generative process to tailor atomic arrangements for a specific XANES spectrum. Finally, our generative model exhibits a remarkable scale-agnostic property, thereby enabling generation of realistic, large-scale structures through learning from a small-scale dataset (i.e., with small unit cells). Our work represents a significant stride in bridging the gap between materials characterization and atomic structure determination; in addition, it can be leveraged for materials discovery in exploring various material properties as targeted.

Hydrogen diffusion mechanisms in the 4130X steel: An integrated study with electrochemical experiments and molecular dynamics simulations

In this work, hydrogen diffusion behavior and mechanisms in the 4130X steel influenced by temperature, locally high concentration, and grain boundary were studied by leveraging both electrochemical hydrogen permeation experiments and molecular dynamics simulations. It was revealed that the hydrogen diffusion coefficient of the 4130X steel was increased with increasing temperature and decreasing locally high hydrogen concentration. The grain boundaries with misorientation below 15° characterized by an electron backscatter diffraction map were identified as hydrogen trapping sites, thus rendering a lower mean square displacement of hydrogen atoms and localized hydrogen diffusion trajectories. Furthermore, at a high hydrogen concentration of 4 at. %, these grain boundaries were saturated by hydrogen atoms, and platelet-like hydrogen clusters were formed within the lattice, which further inhibited the diffusive motion of hydrogen atoms. These findings would deepen our understanding of hydrogen embrittlement mechanisms by establishing the connections between macroscopic permeation behavior and atomic-scale hydrogen diffusion in structural materials.

Fiber‐Dependent 3D Anisotropic Stiffness‐Tunable Biomimetic Intervertebral Disc via Multi‐Material Additive Manufacturing

AbstractLumbar intervertebral disc degeneration is a global musculoskeletal disorder. Total disc replacement is an effective treatment for symptomatic degeneration unresponsive to conservative care. However, current artificial discs, with their joint‐like structural design and homogeneous materials, fail to replicate the 3D anisotropic stiffness of natural discs. Inspired by the intricate structure and material gradient of the natural disc, a biomimetic intervertebral disc is designed and fabricated using multi‐material additive manufacturing. The biomimetic disc exhibits 3D anisotropic stiffness similar to natural discs. By adjusting the hardness, diameter, and arrangement of fibers in annulus fibrosus, the biomimetic disc closely matches the 3D anisotropic stiffness of the natural lumbar disc, exceeding 90% similarity and outperforming existing artificial discs. This highlights the crucial role of fiber properties in disc stiffness regulation and enhances the understanding of biomechanical functions of structures and materials in the annulus fibrosus of human discs. These insights may inspire high‐performance artificial disc designs.

Evaluation of fatigue damage of structural steel based on attenuation of laser-induced surface acoustic wave

ABSTRACT In this paper, the fatigue damage degree of low-alloy structural steel is evaluated by using the attenuation characteristics of laser-induced surface acoustic wave (SAW) during propagation. Taking the typical structural steel material Q345 as an example, a cracks model of fatigue damage is established, and the finite element method is used to solve the model. The results showed that the attenuation coefficient of SAW can reflect the depth and density of fatigue cracks. The surface measurement experiments of specimens with stress cycles of 0, 50000, 100000, 150000, and 200,000 showed that with the increase of stress cycles, the attenuation coefficient of SAW increases as a whole, indicating that it is feasible to evaluate the fatigue damage degree based on the attenuation of SAW. A method of applying tensile stress to the material to improve the sensitivity of fatigue damage evaluation is proposed. The tensile stress is used to offset the horizontal amplitude of the SAW, keeping the fatigue cracks in an open state and increasing the attenuation coefficient of SAW. The attenuation coefficient measurement experiment shows that this method is feasible.

Transforming Nanocrystals into Superhard Boron Carbide Nanostructures.

Boron carbide (B4+δC) possesses a large potential as a structural material owing to its lightness, refractory character, and outstanding mechanical properties. However, its large-scale industrialization is set back by its tendency to amorphize when subjected to an external stress. In the present work, we design a path toward nanostructured boron carbide with greatly enhanced hardness and resistance to amorphization. The reaction pathway consists of triggering an isomorphic transformation of covalent nanocrystals of Na1-xB5-xC1+x (x = 0.18) produced in molten salts. The resulting 10 nm B4.1C nanocrystals exhibit a 4-fold decrease of size compared to previous works. Solid-state 11B and 13C NMR coupled to density functional theory (DFT) reveal that the boron carbide nanocrystals are made of a complex mixture of atomic configurations, which are located at the covalent structural chains between B11C icosahedral building units. These nanocrystals are combined with a spark plasma-sintering-derived method operated at high pressure. This yields full densification while maintaining the particle size. The nanoscaled grains and high density of grain boundaries provide the resulting nanostructured bodies with significantly enhanced hardness and resistance to amorphization, thus delivering a superhard material.

Corrosion of Steels in Liquid Bismuth–Lithium Alloy

The corrosion resistance of several types of steel (AISI 410, 321, 316L, 904L) was determined in a liquid Bi-Li (5 mol.%) alloy (BLA) medium at 650 °C combining gravimetric analysis of steel samples and chemical analysis of corrosion products’ content accumulating in the BLA phase. Energy dispersive X-ray spectrometry, scanning electron microscopy, X-ray fluorescence and inductively coupled plasma–atomic emission spectrometry analysis were employed for characterizing steel structure and alloy composition. AISI 321, 316L and 904L nickel-containing corrosion-resistant steels underwent severe corrosion in BLA, and their corrosion rates depended on the nickel content in the material. AISI 410 steel exhibited the lowest corrosion rate of all the materials investigated, and this type of steel can be considered as a reasonable structural material for work in BLA environments. The corrosion rates of AISI 410, 321, 316L and 904L steels in BLA at 650 °C were 77, 244, 252 and 280 µm/year, respectively. It was also found that chromium was etched more intensively than iron from the surface of steel samples.

Investigation of the corrosion behavior of 29NC alloy in LiCl-KCl melt at 500 oC depending on the content of Li2O and LiOH from 0 to 2 mol. %

Molten chloride salt electrolytes are promising for use as a working medium for the implementation of high-temperature technologies. Alkali metal chlorides are an aggressive environment in relation to structural materials. One of the possible methods of reducing the corrosion damage of a structural material is the method of oxygen passivation of the surface of a metal or alloy by introducing a certain amount of oxygen-containing additives into the melt. The article considers the effect of oxygen-containing impurities (lithium oxide and lithium hydroxide) on the corrosive behavior of a metal material — an alloy of the composition iron–cobalt–nickel. To assess the corrosion resistance of materials, gravimetric analysis, micro-X-ray spectral analysis (XRSA) of the surface and cross-section sections, and X-ray phase analysis (XRF) of the sample surface were used. The dependences of the corrosion rate of the material on the concentration of oxygen-containing additives Li2O and LiOH are presented. Based on the data set of gravimetric, MRSA and XRF data, it was found that 29NC alloy samples in the LiCl–KCl–nLi2O salt melt are not susceptible to corrosion, but in the LiCl–KCl–nLiOH melt, the speed of the 29NC alloy increases significantly due to the interaction of the LiOH additive with the most electronegative component of the alloy — iron.

Investigation of ablation threshold and microchannel fabrication on stainless steel using ultrafast laser

ABSTRACT Ultrafast laser processing is a highly versatile tool for creating microscale structures in many materials. The ablation and micromachining characteristics of AISI 304 stainless steel were examined using a femtosecond-pulsed laser. Parameters such as power, scanning speed, transverse overlap, scanning strategies, and shielding gases were systematically varied. The ablation threshold fluence for SS 304 was calculated as 0.16 J/cm2. Two ablation regimes were observed: the gentle regime, where smooth crater walls were formed under low pulse energy (below 20 µJ), and the strong regime, characterized by rough walls created under high pulse energy (above 20 µJ). The optimal parameters for fabricating microchannels on SS 304 surfaces comprised a laser power of 100 mW, a scanning speed of 30 mm/s, a line-to-line distance of 5 µm, and a parallel scan strategy along the major axis. This study provides a practical approach for enhancing the microchannel fabrication process on stainless steel.

Layer-by-layer assembling boron nitride/polyethyleneimine/MXene hierarchical sandwich structure onto basalt fibers for high-performance epoxy composites

Interfacial adhesion directly affects the mechanical properties of basalt fiber (BF)-reinforced polymer composites. To construct a more superior interphase between BFs and epoxy resin (EP) than a weak interphase of the unmodified BF/EP, we propose a hierarchical sandwich structure consisting of sodium hydroxide–activated boron nitride (BNOH), polyethyleneimine (PEI), and MXene (MX, Ti3C2Tx) through facile layer-by-layer self-assembly. The fabricated BNOH/P/MX sandwich structure (P denoting “PEI”) can synergistically improve the interface adhesion by enhancing the mechanical interlocking and chemical bonding of the composites. When the composites reinforced by BF–BNOH/P/MX subject to the external loading, flexible PEI molecules allow two-dimensional (2D) rigid BNOH and MX nanosheets to slip at the interface by uncurling the molecular chains, dissipating a great amount of energy during the fracture progress. Meanwhile, the hierarchical BNOH/P/MX sandwich structure acts as an excellent interface and possesses multistage gradient modulus and wider thickness, uniformly and efficiently transferring the stress from the EP matrix to BFs. The interfacial shear strength, impact strength, and fracture toughness of BF–BNOH/P/MX-reinforced EP composite are substantially improved by 45.9 %, 60.6 %, and 148.9 %, respectively, compared with bare BF–based composites. This study can provide valuable references and inspirations for designing and constructing high-quality interfaces for high-strength and high-toughness BF structural materials, taking advantage of 2D materials.

Strengthening of Masonry Structures by Sisal-Reinforced Geopolymers

The development of alternative environmentally friendly and sustainable materials in the construction industry has become a fundamental area of research. The current cementitious materials used in existing retrofitting techniques for masonry structures are unsustainable from an environmental point of view. The geopolymer, as a suitable alternative to ordinary Portland cement (OPC), has attracted interest in the last 20 years due to its environmental sustainability and improved properties compared to conventional concrete. To improve the ductile behavior of geopolymers, the adoption of fibers has been widely proposed in the scientific literature for a broad range of applications. The adoption of natural fibers can make geopolymers more advantageous based on their intrinsic environmental sustainability. The aim of this paper is to validate the performance of sisal fiber-reinforced geopolymer plaster as a strengthening material for masonry structures, which will be achieved by modeling the mechanical behavior of geopolymer samples in two different phases. The first phase accounts for the experimental results suitably obtained in the laboratory, while the second phase models the behavior of a masonry panel reinforced with geopolymer plaster using a suitable FEM model in Abaqus.