Metal Lattice Research Articles

Structural Phase Transitions of Mg2NiH4 Induced by NiH4 Molecular Ion Distortion and Metal Lattice Deformation under High Pressures.

Experimental observations indicate that pressure treatments transform the monoclinic and orthorhombic low-temperature phases of Mg2NiH4 into an unresolved pseudocubic phase even at room temperatures, resembling the temperature-induced phase transformation of the material. This pressure-induced phase transformation is anticipated to involve deformations of the tetrahedrally bonded NiH4 molecular ion and the metal lattice. However, the precise mechanism underlying this transformation remains unclear. To elucidate this behavior, this study adopted first-principles density functional theory calculations to investigate the effect of applied pressure on the observed phase transition. The results revealed that the phase transition from the low-temperature phases to the pseudocubic phase occurs at approximately 8-9 GPa. Furthermore, at this pressure, the metal lattice deforms into an antifluorite-like structure, and the NiH4 molecular ion undergoes substantial distortion, resulting in the alignment of hydrogen atoms along the crystal axes of the metal lattice. Furthermore, through a comprehensive structural exploration, we successfully identified several tetragonal and orthorhombic models that are energetically more stable than the low-temperature phases at low pressures. These models are potential candidates for elucidating the pseudocubic phase observed in experiments. Overall, our findings are anticipated to enhance the current understanding of the structural changes occurring during pressure and temperature-induced phase transitions.

In-plane crashworthiness study of bio-inspired metallic lattice structure based on deep-sea glass sponge

Inspired by the double-diagonal reinforced configuration of deep-sea glass sponges, a metallic bio-inspired lattice structure (BLS) was fabricated using additive manufacturing (AM) techniques. In-plane quasi-static compression tests demonstrated the energy absorption (EA) of BLS was improved by about 60 % compared to conventional lattice designs. Subsequent experimental and numerical investigations examined the effects of wall thickness, elucidating the corresponding variations in crashworthiness indicators. The study revealed that when the wall thickness increased from 0.40 mm to 0.60 mm, the EA and mean crushing force (Pm) exhibited a substantial increment of 58.1 % and 91.1 %, respectively. The finite element (FE) simulations underwent experimental validation, exhibiting satisfactory agreement. Parametric studies using the validated FE model explored the effects of geometric factors, such as diagonal distance, unit size, unit number and graded thickness on the crushing performance of BLS. Results indicated that enhancing the EA performance of BLS was achievable by concurrently reducing the unit size and increasing the unit number. The maximum EA achieved was 3535.5 J, representing a 62.9 % improvement compared to the initial configuration, which exhibited an EA of 2170.7 J. Additionally, the introduction of graded thickness facilitated a controllable collapse pattern, thereby improving the crashworthiness performance. Lastly, the in-plane dynamic crushing simulations were conducted, identifying three distinct collapse patterns, where the U-Mode exhibiting a negative Poisson's ratio (NPR) behavior. A deformation mode map and rigid-perfectly plastic-lock (R-PP-L) model were developed to evaluate the dynamic response of BLS under varying relative density (RD) and impact velocity (V). These findings provided valuable insights for designing sponge-inspired structures with enhanced crashworthiness performance.

Characterization of the structural features of Ti-6Al-4V hollow-strut lattices fabricated by laser powder bed fusion

Hollow-strut metal lattices are novel cellular materials. Compared to their solid-strut counterparts, their powder bed fusion additive manufacturing (PBF-AM) features remain largely uninvestigated. This work focuses on characterizing the hollow-strut internal channel and nodal profiles, the defects and microstructures of the hollow-strut thin walls, and the inner surface conditions of the LPBF-manufactured body-centred cubic (BCC) Ti-6Al-4V hollow-strut lattices with different relative densities. BCC lattices are selected because of the low inclination angle (35.26°) of their constituent struts. These low-inclination hollow struts are designed using a recent model developed for PBF of inclined solid struts, together with considerations to prevent powder occlusion and ensure easy removal of powder particles. Detailed characterization indicates that our design considerations resulted in high-quality hollow-strut BCC Ti-6Al-4V lattices, which provide useful design insights for PBF-AM of hollow-strut metal lattices. In terms of microstructure, the Ti-6Al-4V hollow-strut thin walls (≤ 0.5 mm thick) exhibited different microstructures compared with Ti-6Al-4V solid struts, due to the heat accumulation effect in the inner channels. The implications are discussed for in-situ microstructure control.

Imperfection-Enabled Strengthening of Ultra-Lightweight Lattice Materials.

Lattice materials are an emerging family of advanced engineering materials with unique advantages for lightweight applications. However, the mechanical behaviors of lattice materials at ultra-low relative densities are still not well understood, and this severely limits their lightweighting potential. Here, a high-precision micro-laser powder bed fusion technique is dveloped that enables the fabrication of metallic lattices with a relative density range much wider than existing studies. This technique allows to confirm that cubic lattices in compression undergo a yielding-to-buckling failure mode transition at low relative densities, and this transition fundamentally changes the usual strength ranking from plate > shell > truss at high relative densities to shell > plate > truss or shell > truss > plate at low relative densities. More importantly, it is shown that increasing bending energy ratio in the lattice through imperfections such as slightly-corrugated geometries can significantly enhance the stability and strength of lattice materials at ultra-low relative densities. This counterintuitive result suggests a new way for designing ultra-lightweight lattice materials at ultra-low relative densities.

Stochastic or deterministic: Duality of fatigue behaviour of 3D-printed meta-biomaterials

The two deformation modes of meta-biomaterials during cyclic loading have been revealed: stochastic and deterministic strut failure processes. Biomimetic Voronoi structures with a range of strut thicknesses and number of cells per unit volume are printed. We show that when the strut thickness is 200 μm or above, the fatigue fracture process of the lattice is deterministic and the fatigue scatters are below 15%. As the strut is thinned to 150 μm, the local failures occur randomly within the structure, which may lead to a high fatigue scatter (>30%). The two distinct behaviours result from the processing limit of the laser powder bed fusion technique. We demonstrate that the fatigue scatter and the location of the failure process within the lattice are related to the probability that a cluster of unconnected struts larger than a critical value can exist within the lattice. Unlike solid parts, porosity hardly triggers any damage in metallic lattices during cyclic deformation. The discovery of the Janus-like failure process opens up our understanding of meta-biomaterials and defines the pathway towards the design of mechanically durable intricate implants.

Molecular dynamics study of the influence of carbon impurity on austenite nanoparticles crystallization during rapid cooling

The molecular dynamics method was used to study the structure formation during austenite nanoparticles crystallization in the presence of carbon impurities. The paper describes the dependence of the melt cooling rate, particle size, concentration of carbon atoms in the particle on the resulting structure features during crystallization and temperature of the crystallization onset. Formation of the nanocrystalline structure of nanoparticles can be controlled by varying the cooling rate and introducing a carbon impurity: at a cooling rate above 1013 K/s in the model used, crystallization did not have time to occur; at a rate below 5·1012 K/s, the austenite particle crystallized to form a nanocrystalline structure. At the same time, with a decrease in the cooling rate, a decrease in the density of defects in the final structure was observed. At a rate of 5·1011 K/s or less, crystallization of carbon-free particles took place with the formation of low-energy grain boundaries (with a high density of conjugate nodes: special boundaries, twins). The crystallization temperature during cooling at a rate below 1012 K/s is inversely proportional to the particle diameter: as the particle size decreases, the proportion of free surface increases, which leads to a decrease in the probability of crystalline nuclei formation. In addition, the crystallization temperature increases with a decrease in the cooling rate. The introduction of a carbon impurity led to a decrease in the crystallization temperature of nanoparticles: in the presence of 10 at. %. As a percentage of carbon, it decreased by about 200 K for particles of different sizes. Carbon atoms often formed clusters consisting of several carbon atoms. Such clusters distorted the resulting crystal lattice of metal around them, preventing crystallization. In the presence of a carbon impurity, the final structure of the crystallized particles contained a higher density of grain boundaries and other defects. Carbon atoms, especially clusters of them, were fixed mainly at grain boundaries and triple joints.

Hydrogen diffusion and hydrogen embrittlement in iron (steel)

This article examines the diffusion of hydrogen (H-diffusion) and the temperature dependences of the diffusion coefficient of hydrogen (DH) in the metal (M)-hydrogen system. The metal used was iron and low-alloy steel. Taking into account experimental data on hydrogen diffusion in the Fe-H and steel-H systems, the main diffusion parameters were calculated and compared. It is shown that the temperature dependences of the hydrogen diffusion coefficient in metal samples in a one-stage reaction under isothermal conditions are described by the Arrhenius equation. For some M-H systems, experimental data show a deviation of the diffusion coefficient from the ideal one calculated using the Arrhenius equation. This discrepancy can be eliminated using the statistical theory of absolute reaction rates. For the temperature range 25–1250 oС, the pre-exponential coefficient and activation energy of hydrogen diffusion in a body-centered cubic (bcc) lattice of iron (α–Fe) were calculated using the Arrhenius equation. These parameters make it possible to describe the dependence of the rate of hydrogen diffusion in a metal on temperature and to predict the behavior of hydrogen diffusion when changing the conditions of the kinetic process (concentration of substances, pressure, structure, composition, etc.). Tabular values of the calculated pre-exponential factor and activation energy of hydrogen diffusion in previously studied iron-based samples are presented. The temperature dependences of the hydrogen diffusion coefficient in a lattice of iron α–Fe can be divided into low-temperature and high-temperature regions. The calculated diffusion parameters of hydrogen in the metal lattice for the low-temperature 25– 800 oC and high-temperature 800–1250 oC regions differ markedly from each other. In addition, these calculated values are significantly influenced by the structure and composition of the metal. We also studied the diffusion of hydrogen in α-iron using ab initio density functional calculations. Molecular dynamics calculations using transition state theory were used. The calculated diffusion coefficient of hydrogen in α-Fe is consistent with previously obtained experimental data. Hydrogen embrittlement (HE) is considered using internal pressure, hydrogen enhanced localized plasticity (HELP) and hydrogen enhanced decohesion embrittlement (HEDE) theories.

Understanding the Activity and Stability Relationship on Metal Oxide Surfaces during the Electrochemical Generation of Reactive Oxygen Species

Inappropriate waste disposal is a significant anthropogenic source of water pollution. This action is responsible for the release of a variety of pollutants into water bodies, including heavy metals, inorganic and organic compounds, which can have severe consequences for aquatic ecosystems and human communities.[1] Particularly, some organic contaminants such as Bisphenol A (BPA) and Per- and Polyfluoroalkyl Substances (PFAS) commonly found in trace concentrations can remain in the environment due to their high resistance to breakdown.[2] Thus, the development of highly effective water remediation technologies is a challenge.Electrochemical methods stand out among the array of tools due to their ability to eliminate pollutants effectively and selectively in an environmentally friendly way. The advantage of the method is tied to the electrochemical advanced oxidation processes (EAOP), which involve the generation of highly reactive oxygen species (ROS), such as hydrogen peroxide (H2O2), ozone(O3), and hydroxyl radicals (•OH). These species can indirectly mineralize organic pollutants to CO2 and H2O. The ROS generation is related to the electrocatalyst's nature, being limited for some classes of materials, such as metal oxides (PbO2, SnO2, TiO2, WO3), and Boron-Doped Diamond (BDD).[2-5] Despite their highly reactive nature, we still know very little about the impact of ROS on the surface stability of metal oxide surfaces that show a high overpotential for the oxygen evolution reaction (OER), and therefore, are believed to generate predominantly ROS at high electrode potentials (e.g., >1.7 V vs reversible hydrogen electrode, RHE). Concerning the electrocatalysts' stability, the eventual deactivation constitutes a pivotal parameter with significant implications for the operational cost to commercialize this water remediation approach.Hence, to understand the trends in surface stability of metal oxides and their correlation to the activity toward ROS formation, we have deployed a combination of in situ electrochemical methods that allow us to directly measure the reaction rates (current) simultaneously with metal dissolution rates using the Stationary Probe Rotating Disk Electrode-ICP-MS method, and selectivity for the formation of O2, H2O2. Ou study framed metal oxides typically considered non-active for oxygen evolution and capable of generating ROS, such as PbO2, SnO2, TiO2, and ZnO.[3] To establish a comparative benchmark, we also utilized IrO2, known as a good OER catalyst due to its high activity-stability factor (ASF).[6-8] Figure 1 shows a set of cyclic voltammetry data obtained from a PbO2 surface in 0.1 mol L-1 NaOH. Although we observe oxidation currents only above 1.9 V vs RHE, monitoring the ring current at two different potentials reveals close to 100% selectivity towards O2 evolution and below 0.2% for H2O2 up to 2.2 V, while the onset of metal dissolution occurs above 2.1V. This result suggests that O2 evolution is still present even on materials that require very high overpotentials, and that metal dissolution might be intrinsically related to the formation of O2 and ROS from the electrolyte’s adsorbed oxygen anions on the metal oxide surface and/or (ionically) bonded oxygen anions in the metal lattice as expected from thermodynamic considerations.[9] Such fundamental comprehension about how the dissolution process impacts the activity of the surface sites for ROS generation can guide the design of not only active but also stable materials for water remediation systems.[10]

Disclosing magnetic clusters in the metallic half-Heusler ferromagnet Cr4PtGa17 with a breathing pyrochlore lattice

We report a ferromagnetic resonance (FMR) study of a single crystal of Cr4PtGa17, the first material of a half-Heusler (HH) type with a metallic ferromagnetic breathing pyrochlore structure. The spatial distribution of the magnetic free energy density derived from the FMR data appears to be of a cubic symmetry despite the lower symmetry coordination of magnetic Cr ions. This surprising finding strongly suggests that the Cr4Ga14 structural unit at the Y site of the HH general XYZ formula forms an octahedrally shaped integral magnetic cluster, likely due to strong exchange interaction between the Cr ions via covalent Cr-Ga-Cr bonds. The presence of magnetic clusters within a regular metallic lattice appears to be a new intriguing characteristics of these novel types of HH compounds whereas Cr4PtGa17, at the same time, constitutes the rare example of such metallic pyrochlore-type material.

A multifunctional heterogeneous structure inspired by shell brick-mud structure: Balancing noise reduction and mechanical performance

Electric armoured vehicles, which are crucial for strategic operations, must possess superior mechanical properties and noise reduction to maintain normal functionality. However, achieving high energy absorption and noise reduction performance simultaneously is challenging with a single uniform material or structure. This study introduces heterogeneous structures with metal lattice skeletons filled with polymer materials. The skeleton, known as the bionic mantis shrimp structure (BMS), is filled with polyurethane and epoxy. Impedance tube experiments revealed that the sound absorption coefficients of Heterostructure-polyurethane foam (HS-PU) and Heterostructure-epoxy (HS-EP) are significantly higher than BMS. HS-PU achieved an average sound insulation of 33.6 dB, marking a 739 % improvement over BMS. Compression tests show that polymer filling can inhibit the destructive collapse of BMS and enhance its mechanical performance. HS-EP exhibits specific strength and specific energy absorption values of 57 MPa/(g·cm−3) and 30.75 J/g, respectively, representing an increase of 67.6 % and 315 % compared to BMS. Additionally, as the volume fraction of BMS increased in the heterogeneous structure, the elastic modulus and compressive strength increase while the specific energy absorption decreased. This research suggest that the design of metal/polymer heterogeneous structures offers a promising approach for developing high-strength and noise-reducing protective structures.

Assessing Hydrogen Embrittlement in Pipeline Steels for Natural Gas-Hydrogen Blends: Implications for Existing Infrastructure

Governments worldwide are actively committed to achieving their carbon emission reduction targets, and one avenue under exploration is harnessing the potential of hydrogen. Blending hydrogen with natural gas is emerging as a promising strategy to reduce carbon emissions, as it burns cleanly without emitting carbon dioxide. This blending could significantly contribute to emissions reduction in both residential and commercial settings. However, a critical challenge associated with this approach is the potential for Hydrogen Embrittlement (HE), a phenomenon wherein the mechanical properties of pipe steels degrade due to the infiltration of hydrogen atoms into the metal lattice structure. This can result in sudden and sever failures when the steel is subjected to mechanical stress. To effectively implement hydrogen-natural gas blending, it is imperative to gain a comprehensive understanding of how hydrogen affects the integrity of pipe steel. This necessitates the development of robust experimental methodologies capable of monitoring the presence and impact of hydrogen within the microstructures of steel. Key techniques employed for this assessment include microscopic observation, hydrogen permeation tests, and tensile and fatigue testing. In this study, samples from two distinct types of pipeline steels used in the natural gas distribution network underwent rigorous examination. The findings from this research indicate that charged samples exhibit a discernible decline in fatigue and tensile properties. This deterioration is attributed to embrittlement and reduced ductility stemming from the infiltration of hydrogen into the steel matrix. The extent of degradation in fatigue properties is correlated not only to the hydrogen content but also to the hydrogen permeability and diffusion rate influenced by steel’s microstructural features, with higher charging current densities indicating a more significant presence of hydrogen in the natural gas pipeline blend.

Floquet Modification of the Bandgaps and Energy Spectrum in Flat-Band Pseudospin-1 Dirac Materials

In this paper, we investigate the so-called electronic dressed states, a unified quasiparticle resulting from the interaction between electrons in a two-dimensional material with an off-resonance optical dressing field. If the frequency of this field is much larger than all characteristic energies in the system, such as the Fermi energy or bandgap(s), the electronic band structure is affected by radiation so that some important properties of the electron dispersions could be modified in a way desirable for practical applications. For example, circularly polarized light can be used to vary the bandgap of Dirac materials: it opens a gap in graphene and other metallic and semimetallic lattices, or it modifies the magnitude of an existing gap. This will either enhance or reduce a gap, depending on its initial value as well as properties of a host material. Here, we consider gapped dice and Lieb lattices as samples, and we put forward a full theoretical model to reveal how these electronic states are deformed by elliptically-polarized irradiation with a focus on the generation and modification of a bandgap.

Rainbow trapping of out-of-plane mechanical waves in spatially variant beam lattices

We numerically and experimentally investigate the propagation of mechanical waves in two-dimensional periodic and spatially graded elastic beam lattices. Experiments on metallic lattices admit the characterization of the linear elastic wave dispersion over a wide range of frequencies, resulting in complete, experimentally-constructed dispersion surfaces in excellent agreement with predictions obtained from finite element-based Bloch wave analysis. While Timoshenko beam theory is shown to be sufficiently accurate for predicting the lowest modes, experiments prove that solid finite elements are required to capture the dispersion relations at higher frequencies as well as when mode coupling occurs. Based on an improved numerical procedure, group velocity maps further highlight the directionality of wave dispersion and allow for the simple identification of bandgaps. In addition to classically studied periodic trusses, we extend the framework to spatially graded structures and demonstrate acoustic rainbow trapping in beam lattices undergoing out-of-plane vibrations. Our experiments confirm broadband vibration attenuation of the typical meta-wedge type previously observed only in optics and few mechanical studies. Results further show convincing agreement between Bloch theory-based predictions, finite element simulations, and experimental measurements. Such spatially-variant architected lattices show great promise for steering the motion of elastic waves in applications from wave guiding and wave shielding to energy harvesting.

Evaluation of Lattice Structures for Medical Implants: A Study on the Mechanical Properties of Various Unit Cell Types

Lattice structures are a prime candidate for applications in the medical implant industry due to their versatile mechanical behaviour, which can be tailored to meet specific patient needs and reduce stress shielding, while enabling the natural flow of body fluids. In this work, the mechanical properties of metallic lattices made of five different unit cell types, Cubic (C), Truncated Octahedron (TO), Truncated Cubic (TC), Rhombicuboctahedron (RCO), and Rhombitruncated Cuboctahedron (RTCO), were evaluated under uniaxial compression at three different relative densities, 5%, 15%, and 45%. The evaluation was experimental, and it was compared with previous and new finite element simulations. Specimens for the experimental tests were fabricated in stainless steel 316L by laser powder bed fusion, and stress–strain curves were obtained for the different lattices. The combination of the test results with a critical interpretation of the deformation mechanisms allowed us to confirm that two unit cell types, TO and RTCO, are stable for the whole range of relative densities evaluated. The other three unit cells exhibit more unpredictable behaviour, either due to manufacturing defects or limitations, or because their unstable compression behaviour leads to bucking. For these reasons, TO and RTCO unit cell types are mechanically more adequate for applications in the medical implant industry.

Boron-Induced Interstitial Effects Drive Water Oxidation on Ordered Ir-B Compounds.

Interstitial filling of light atoms strongly affects the electronic structure and adsorption properties of the parent catalyst due to ligand and ensemble effects. Different from the conventional doping and surface modification, constructing ordered intermetallic structures is more promising to overcome the dissolution and reconstruction of active sites through strong interactions generated by atomic periodic arrangement, achieving joint improvement in catalytic activity and stability. However, for tightly arranged metal lattices, such as iridium (Ir), obtaining ordered filling atoms and further unveiling their interstitial effects are still limited by highly activated processes. Herein, we report a high-temperature molten salt assisted strategy to form the intermetallic Ir-B compounds (IrB1.1) with ordered filling by light boron (B) atoms. The B residing in the interstitial lattice of Ir constitutes favorable adsorption surfaces through a donor-acceptor architecture, which has an optimal free energy uphill in rate-determining step (RDS) of oxygen evolution reaction (OER), resulting in enhanced activity. Meanwhile, the strong coupling of Ir-B structural units suppresses the demetallation and reconstruction behavior of Ir, ensuring catalytic stability. Such B-induced interstitial effects endow IrB1.1 with higher OER performance than commercial IrO2, which is further validated in proton exchange membrane water electrolyzers (PEMWEs).

Simulation study of compressive mechanical properties of spheroidal cytosolic lattice structures

Ultra-lightweight metallic lattice structures are lightweight functional materials, and the design of their cell elements is a focus of research. Based on the idea of hollow sphere and lattice structure, this paper designs a kind of spherical cytosolic lattice structure, investigates its mechanical properties when compressed by numerical simulation, analyzes its deformation law, derives the nominal stress-strain curve, and investigates the effects of the rod diameter and the cytosolic sphere center distance on the structure’s properties of the effective modulus of elasticity, yield limit, plateau stress, energy absorption and specific energy absorption. The results of the study show that the compressive deformation of the structure exhibits three types depending on the spherical center distance. The mechanical properties of the structure, such as effective modulus of elasticity, yield limit, and plateau stress, show a pattern of decreasing and then increasing with the increase of the spherical center distance, and the minimum value is reached when the spherical center distance is 9.0, but the specific energy absorption of the structure shows a pattern of increasing and then decreasing, and it reaches the maximum value when the spherical center distance is 9.6 mm. The validity of the numerical analog simulation analysis was experimentally verified by 3D printing specimens.

Energy absorption performance of woven metallic lattices with orthogonal spiral wires under quasi-static compression

Woven metallic lattice (WML) structures are gaining attention for their beneficial mechanical properties, such as low weight and special energy absorption capability. They hold potential for diverse applications, including energy absorption components in aerospace. Drawing inspiration from the traditional double-arrow lattice, this study proposes a novel WML design featuring multi-plateau stresses. The deformation behavior of this structure under compression was investigated using finite element analysis and experimental methods. Three gradient structures defined by the different layer arrangements along load direction associated with specific structure variables, namely positive gradient (PG), negative gradient (NG), and hybrid gradient (HG), were introduced, along with an examination of their mechanical properties. The study explored the influence of key parameters of the cell structure on compression characteristics. Findings suggest that enhancing cell vertex angle and wire diameter can improve energy absorption, while the opposite holds true for cell base angle. Among the gradient structures analyzed, the PG WML structure demonstrates optimal energy absorption due to its dual-plateau stress characteristics. The NG WML structure is noteworthy for its uniform lattice deformation during initial compression stages, which is crucial for precision engineering with subtle deformation control strategies. Lastly, the deformation pattern of the HG WML structure during compression progresses from low to high strength.

A Review on hydrogen embrittlement behavior of steel structures and measurement methods

Hydrogen can be found within metals under a variety of industrial and environmental conditions. Hydrogen-metal interactions can take place through hydrogen embrittlement, hydrogen sulfide corrosion, or hydrogen absorption. Steel and other metals that are exposed to hydrogen may experience a difficulty known as hydrogen embrittlement that affects their mechanical properties. The material's ductility and toughness may be reduced as a result of this phenomena, it also increasing the risk of brittle fracture. In steel, atomic hydrogen mainly diffuses into the microstructure of the steel, causing hydrogen embrittlement. Localized weakening of the bonds between the metal atoms might result from hydrogen atoms occupying interstitial positions in the metal lattice. Especially when under stress, this may lead to a more susceptible to fracture and cracking. Concerns with hydrogen embrittlement arise in sectors like aerospace and oil and gas that use high-strength steels. If not appropriately handled, it may result in catastrophic failures. Use of hydrogen-resistant alloys, appropriate heat treatments, and protection from conditions that promote hydrogen uptake are examples of preventive measures. This literature review paper covers the definition of hydrogen embrittlement (HE), mechanisms causing HE, measurement of hydrogen concentration and preventive measures that restrict hydrogen diffusion to the steel.

Construction of Two-Dimensional Organometallic Coordination Networks with Both Organic Kagome and Semiregular Metal Lattices on Au(111).

Two-dimensional metal-organic networks (2D MONs) having heterogeneous coordination nodes (HCNs) could exhibit excellent performance in catalysis and optoelectronics because of the unbalanced electron distribution of the coordinating metals. Therefore, the design and construction of 2D MONs with HCNs are highly desirable but remain challenging. Here, we report the construction of 2D organometallic coordination networks with an organic Kagome lattice and a semiregular metal lattice on Au(111) via the in situ formation of HCNs. Using a bifunctional precursor 1,4-dibromo-2,5-diisocyanobenzene, the coordination of isocyano with Au adatom on a room-temperature Au(111) yielded metal-organic coordination chains with isocyano-Au-isocyano nodes. In contrast, on a high-temperature Au(111), a selective debromination/coordination cascade reaction occurred, affording 2D organometallic coordination networks with phenyl-Au-isocyano nodes. By combining scanning tunneling microscopy and density functional theory calculations, we determined the structures of coordination products and the nature of coordination nodes, demonstrating a thermodynamically favorable pathway for forming the phenyl-Au-isocyano nodes.

Boron‐Induced Interstitial Effects Drive Water Oxidation on Ordered Ir‐B Compounds

Interstitial filling of light atoms strongly affects the electronic structure and adsorption properties of the parent catalyst due to ligand and ensemble effects. Different from the conventional doping and surface modification, constructing ordered intermetallic structures is more promising to overcome the dissolution and reconstruction of active sites through strong interactions generated by atomic periodic arrangement, achieving joint improvement in catalytic activity and stability. However, for tightly arranged metal lattices, such as iridium (Ir), obtaining ordered filling atoms and further unveiling their interstitial effects are still limited by highly activated processes. Herein, we report a high‐temperature molten salt assisted strategy to form the intermetallic Ir‐B compounds (IrB1.1) with ordered filling by light boron (B) atoms. The B residing in the interstitial lattice of Ir constitutes favorable adsorption surfaces through a donor‐acceptor architecture, which has an optimal free energy uphill in rate‐determining step (RDS) of oxygen evolution reaction (OER), resulting in enhanced activity. Meanwhile, the strong coupling of Ir‐B structural units suppresses the demetallation and reconstruction behavior of Ir, ensuring catalytic stability. Such B‐induced interstitial effects endow IrB1.1 with higher OER performance than commercial IrO2, which is further validated in proton exchange membrane water electrolyzers (PEMWEs).