There are a few examples of alloys with two or more passivating components where the specific role of each component in forming the passive film is understood. We examined the electrochemical passivation behavior of Fe1-xCrxVy alloys in 0.1 M H2SO4 in terms of the Cr + V content. Our results showed that for y $$\le$$ 0.04 we obtained an excellent fit to the percolation passivation theory, but for y > 0.04, the theory underestimated the number of monolayers dissolved in order for passivation to occur by about a factor of two. The chemical short-range order parameters for the alloys were characterized using neutron scattering; however, the differences among the alloys for y $$\le$$ 0.04 and y > 0.04 were minimal. Energy and wavelength dispersive spectroscopy revealed that all the alloys contained nanometer-scale V-oxygen clusters that served as sites for the initiation of pitting. Pit densities, pit diameters and pit depths were characterized using focused ion-beam machining, scanning electron microscopy and digital image analysis. These results allowed us to develop an analysis based on Faraday’s law for the difference in the number of monolayers dissolved for y = 0.04 and y > 0.04, and we found excellent agreement between our experimental results and the analysis. Our results provide a path forward for evaluating passivation behaviors of alloys that exhibit pitting.
Enhancing the corrosion resistance of aluminum (Al) matrix composites remains a significant challenge due to the inherent interfacial instability between the matrix and carbon nanotubes (CNTs). This study reports a superior corrosion inhibition mechanism in interfacially engineered Al-O/CNT composites, driven by the formation of robust Al-O-C chemical anchoring. We comparative analyzed the electrochemical degradation of pure Al, Al/CNT, and Al-O/CNT through salt spray tests and density functional theory (DFT) simulations. SEM analysis revealed that the Al-O/CNT composite exhibited the thinnest corrosion layer 0.45 μm, significantly outperforming Al/CNT (0.86 μm) and pure Al (2.45 μm). Furthermore, the Al-O/CNT composite demonstrated a negligible net mass gain of only 0.15 mg/cm2, which is significantly lower than those of Al/CNT (1.84 mg/cm2) and pure Al (2.12 mg/cm2). XPS analysis demonstrated that the Al-O-C interface effectively suppresses the hydration of the Al2O3 passive film into unstable Al(OH)3, while enabling a near-complete (99.8%) immobilization of metal chlorides at the interface to prevent deep Cl- penetration. DFT calculations corroborated these findings, revealing a thermodynamic shift from weak mechanical interlocking (−3.52 eV) to stable chemical anchoring (−5.72 eV). This high interfacial binding energy provides an electronic barrier against electrolyte ingress and stabilizes the protective oxide layer. The synergistic effect of the physical CNT network and the chemically anchored interface establishes a multi-level defense system, offering a new paradigm for designing highly corrosion-resistant metal matrix composites.
Steam coating forms protective boehmite films on aluminum alloys; however, identifying the primary factors governing corrosion resistance remains challenging due to strong descriptor covariance. We established a physics-informed interpretable machine-learning framework to predict pitting potential (Epit) from four physical descriptors: film thickness (FT), surface morphology (SQ), crystallite size (CS), and substrate dislocation density index (FS) using Random Forest (R² = 0.67). SHAP analysis identified SQ and FT as dominate descriptors, while ALE analysis showed that SQ’s role shifts from marking protective coverage in early-growth films to defect-mediated degradation in mature films. Two-dimensional ALE analysis indicated that corrosion resistance arose from region-dependent synergistic interactions among film geometry, crystallinity, and substrate defect structure, with the SQ–CS and FT–SQ pairs showing sign-reversing interaction landscapes rather than a single uniform synergy. Monte Carlo simulations confirmed that measurement-derived uncertainty (~0.080 V) accounts for only a minor fraction of the total model error, indicating residual errors stem mainly from unobserved physical heterogeneities. These findings demonstrate how interpretable machine learning can decouple intertwined physical descriptors and propose candidates for degradation-governing mechanisms in complex process–structure–property systems.
The current study overcomes the limitations of Mg-Li alloys by creating a dataset with 450 data points sourced from literature. Two generative adversarial network (GAN) architectures, non-saturating GAN (NSGAN) with residual generator blocks, spectral normalization and feature matching loss, and Wasserstein GAN with gradient penalty (WGAN-GP) were used to generate augmented datasets. WGAN-GP had relatively better attribute fidelity to the KS/correlation values with composite score of 0.641 than NSGAN augmented data with score of 0.629. NSGAN-augmented data provided ML R2 mean of 0.752 than WGAN-GP with mean of 0.716 across all corrosion targets such as Ecorr, icorr, CR and H2 evolution rate. The NSGAN augmented dataset were combined with experimental data and Bayesian hyperparameter optimization was performed using Optuna m-TPE across five ML models, namely RF, XGBoost, SVR, AdaBoost and CatBoost. The integrated Experimental+NSGAN+CatBoost-HPO framework obtained test R2 values of 0.867, 0.814, 0.814 and 0.763 for Ecorr, icorr, CR and H2 evolution rate, respectively, which are 12.5%, 13.7%, 13.8% and 15.3% higher than experimental CatBoost-HPO baseline. SHAP analysis and permutation importance identified crystal structure as the dominant predictor for all targets. This framework establishes NSGAN-based augmentation as a preferred approach for electrochemical data of Mg-Li alloys.
A novel in situ, non-destructive technique for monitoring localized corrosion based on potential drop array mapping (PDAM) is proposed in this work. An electric-field model is established to derive a calculation formula for localized corrosion depth, and a corrosion-depth mapping dataset is generated using numerical simulations. An artificial neural network (ANN) is then trained to learn the mapping between measured PDAM responses and the corresponding true corrosion depths. This ANN reduces the mean square error (MSE) of the depth predictions from approximately 10−3 mm2 to less than 10−5 mm2, markedly improving the quantitative measurement accuracy. The monitoring system is further evaluated through accelerated electrochemical corrosion experiments, where the absolute error between the measured and actual corrosion depths is less than 0.4 μm. The results confirm the effectiveness and reliability of the method in characterizing non-uniform corrosion on steel surfaces, demonstrating its potential for practical in situ corrosion monitoring applications.
This study investigates the observed corrosion features and possible degradation pathways of an ash-green glazed Qingbai (bluish-white) porcelain sherd recovered from the Nanhai I shipwreck, which was produced at the Hutian kiln in Jingdezhen. A multi-analytical approach was employed to characterize the chemical composition, microstructure, and phase constitution of the sample. The results reveal that the black-brown contaminants in the glaze cracks were identified as FeS2, while the SiOx spheres within the glaze bubbles, some of which possess a well-aligned submicron particle structure, were observed. White spots, arc-shaped cracks, and corrosion pits densely distribute on the glaze surface. We hypothesize that local Mg-bearing environments could have influenced silica alteration. To understand the intrinsic correlation between the corrosion behavior and the original microstructure of the glaze, we provide a fundamental analysis of the processing defects in this specific artifact, referring to traditional Jingdezhen manufacturing techniques.
This work investigates the microbiologically influenced corrosion (MIC) behavior of TC4 titanium alloy fabricated via selective laser melting (SLM-TC4) and conventional forging (Forged-TC4), with Geobacter sulfurreducens as the model electroactive bacterium. Microstructural characterization revealed that SLM-TC4 features finer grains (≈ 4 μm), martensite-like α‘ phases, and denser intragranular dislocations, whereas Forged-TC4 exhibits a basket-weave microstructure with larger grains (≈ 900 μm) and grain-boundary dislocations. Electrochemical tests, surface analysis, and biofilm characterization were employed to evaluate the corrosion performance and MIC mechanisms. Forged-TC4 was found to outperform SLM-TC4 in corrosion resistance, due to its higher content (84.1%) of TiO2 in the passive film. In the presence of G. sulfurreducens, SLM-TC4 suffered more severe corrosion, with a corrosion current density (19.5 nA/cm²) about 2 times higher than Forged-TC4. G. sulfurreducens accelerated corrosion via extracellular electron transfer (EET), reducing TiO₂ content in the passive film and increasing metastable Ti₂O₃. CLSM observations confirmed deeper pitting (6.5 μm) on SLM-TC4 in the bacterial system than on Forged-TC4. This work demonstrates that SLM-induced microstructural characteristics weaken the passive film stability, rendering SLM-TC4 more susceptible to MIC by G. sulfurreducens. Optimizing the SLM process to improve passive film stability is proposed as an effective strategy for mitigating MIC of TC4.
This study investigates the effect of thermo-mechanical densification on the fire behaviour of wood using cone calorimetry. Scots pine wood was thermo-mechanically densified from an initial thickness of 20 mm to target thicknesses of 14 and 10 mm and compared with non-densified specimens of the same thickness as well as non-densified 20 mm samples. For non-densified specimens, the time to ignition (TTI) remained nearly constant (18–20 s) across the investigated thicknesses, indicating thermally thick behaviour. In contrast, delayed ignition was observed for the specimens densified to 10 mm (the higher densification ratio), with TTI increasing to 28 s. While the first peak heat release rate (pHRR) remained comparable across samples, densification increased the time to the second peak heat release rate by up to 85% and its magnitude by approximately 9% relative to non-densified specimens of the same thickness (10 mm). Densification was found to alter the combustion behaviour of wood by modifying the thermal inertia of the material and the characteristics of the resulting char layer, thereby affecting the transport and release of pyrolysis gases and producing distinct effects at different stages of combustion rather than an overall enhancement of fire performance.
Membrane distillation (MD) enables water purification under moderate conditions but relies heavily on fluorinated, non-biodegradable membranes, which raise serious environmental concerns. This Review evaluates four categories of eco-friendly bio-based polymers for MD, linking physicochemical properties, thermal stability, and degradability to operational performance. Comparative analysis under practical conditions highlights relationships between polymer degradability, process stability, water flux, salt rejection, and ecological impact, while identifying key challenges for large-scale adoption.
Direct culturing Human Umbilical Vein Endothelial cells (HUVECs) on Mo reduced viability by ~50% from 24 to 48 h, while an equivalent Mo species maintained >80%, showing cytotoxicity stems from interfacial processes. Local analysis at Mo interface in Hanks’ solution revealed minimal pH change (0.2 unit) but severe oxygen depletion (down to 0.6 ppm) probably facilitated by MoOx. Degrading Mo markedly alters its interfacial microenvironment, likely correlating to cytocompatibility loss.
Polyolefins, commonly used in packaging and single-use products, are notoriously persistent in the environment, contributing significantly to environmental pollution. In scientific literature to date, polyolefins have not been reported to fully biodegrade. This study examines the biodegradation potential of polyolefin materials, specifically polyethylene (PE) and polypropylene (PP), enhanced through the incorporation of Biotransformation Masterbatch technology. The inclusion of the Biotransformation Masterbatch accelerated and enabled the full biodegradation of PE and PP, as demonstrated by laboratory weathering, and biodegradation studies in soil at mesophilic temperatures. Ecotoxicity tests revealed no adverse effects on test organisms in both soil and water environments, while metagenomics analysis demonstrated that biodegradation of these polyolefins did not significantly change the soil microbiota composition, which showed higher metabolic activity compared to virgin plastic controls. These findings demonstrate that Biotransformation technology provides an effective solution for delivering polyolefin-based materials with reduced environmental impact. It offers a sustainable alternative to conventional plastics, preserving the performance characteristics of traditional polyolefins while addressing the problem with fugitive plastic waste in the environment.
Localized corrosion remains a critical challenge limiting the durability and service life of aluminum (Al) alloys. Coarsened intermetallic particles (IMPs), formed during casting and heat treatment, can act as strong cathodic sites and significantly influence the corrosion behavior of Al alloys. In this study, first-principles calculations are performed to examine the oxygen reduction reaction (ORR) activities of Cu- and Fe-based solute clusters and representative IMPs in 2xxx, 6xxx, and 7xxx series aluminum alloys. Our results reveal that Al7Cu2Fe exhibits particularly high ORR activity, making it especially detrimental to corrosion resistance. Finally, through a systematic elemental screening across the periodic table, we discover that boron (B) can be preferentially incorporated into Al7Cu2Fe relative to the Al matrix and can effectively suppresses the cathodic reaction on the Al7Cu2Fe surface. These findings provide atomic-level insights and strategies for improving the corrosion resistance of Al alloys in industrial applications.
In this study, the corrosion behavior of Cr–Ni alloyed 690 MPa-grade weathering steel in simulated marine atmospheric environments was investigated in comparison with commercial E690 steel. After wet/dry cyclic corrosion testing, the corrosion resistance was quantitatively evaluated by weight-loss measurements, while the evolution, structure, and composition of the rust layers formed on the Cr–Ni alloyed 690 MPa weathering steel and commercial E690 steel were characterized using SEM, energy-dispersive spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and electrochemical measurements. The alloying elements Cr and Ni facilitate the development of a compact and protective rust layer by promoting the enrichment of Cr- and Ni-containing oxides and the formation of α-FeOOH, thereby significantly enhancing the corrosion resistance of the E690 weathering steel from the initial stage of corrosion. Furthermore, the Cr–Ni alloyed weathering steel forms a cation-selective rust layer during the corrosion process, which effectively suppresses the penetration of Cl⁻ ions and exhibits superior localized corrosion resistance.
A novel thermal/environmental barrier coating (T/EBC) composed of a Si-15 mol% HfO2 bond coat, a Yb2SiO5-50mol% Yb2Si2O7 intermediate layer, and a (Gd0.2Dy0.2Ho0.2Tm0.2Yb0.2)4Hf3O12 (15SH/50YbMDS/(5RE)4Hf3O12) top layer was fabricated by air plasma spraying (APS). Its oxidation and corrosion behavior in air/water vapor environments at 1450 °C were systematically studied. In air environments exposure, the coating underwent sintering, characterized by the grain growth and surface roughening of (5RE)4Hf3O12 layer. With prolonged oxidation, the micro-cracks become discontinuous and even heal, dominated by the multipoint contacts mechanism. Concurrently, the 15SH bond coat undergoes oxidation, especially at the edge regions. Under water vapor environments, edge regions degraded via (5RE)4Hf3O12 layer dissolution into non-stoichiometric garnet (RE3Al5-xSixO12) and oxygen-deficient hafnates (5RE)4Hf3-xO12-2x), driven by synergistic Si(OH)₄ volatilization and Al(OH)3 attack, while the corrosion of central region was limited. Compared to its oxidized counterpart, the 15SH bond coat underwent more severe oxidation under corrosive environments. The incorporation of HfO2 partially improves the service performance of the 15SH bond coat by reacting with SiO2 to form HfSiO4. These findings provide essential insights into the design of high‑entropy hafnate‑based T/EBCs with enhanced durability in both dry and humid high‑temperature environments.
The emergence of private fusion enterprises, combined with advancements in U.S. and EU ITER-TBM as well as EU DEMO liquid breeder blanket concepts, has renewed focus on the materials challenges. This study examines the compatibility of reduced activation ferritic/martensitic (RAFM) steel in liquid Lithium (Li) containing various Nitrogen (N) concentrations, tested at 600 and 700 °C for 500 and 1000 h under static conditions. Microstructural characterization revealed the corrosion-induced dissolution and precipitation in Li containing 0.082 and 0.17 wt.% N at 600 °C, while limited dissolution and precipitation were observed in N-gettered Li using zirconium (Zr) and titanium (Ti) foils at 600 °C. Tensile testing at room temperature after Li exposure revealed a decrease in strength and ductility of the RAFM steel as a function of N content in Li. Severe embrittlement was observed after 500 h in Li containing 0.17 wt.% N at 600 °C and after 500 h in hot-gettered Li at 700 °C. Chromium (Cr) depletion from the steel matrix was observed, leading to the formation of M6C-type carbides on the surface identified by electron microscopy (SEM), X-ray diffraction (XRD), in agreement with thermodynamic calculations. These findings highlight the critical materials challenges posed by liquid Li breeder blanket concepts, emphasizing the need for improved strategies to address Li-induced dissolution, precipitation, and steel embrittlement due to N contamination of the coolant.
Liquid-metal embrittlement (LME) in Zn-coated steels is traditionally understood as a consequence of liquid Zn penetration along grain boundaries (GBs) during thermo-mechanical processing. However, recent thermodynamic predictions brought to light a massive Zn segregation transition at Fe GBs that suggest a strong driving force for intermetallic phase formation at substantially lower temperatures than the melting point of Zn. Leveraging bulk mechanical testing, high-energy synchrotron diffraction, and transmission electron microscopy, we demonstrate here that embrittling Fe-rich intermetallic grain-boundary phases emerge in an advanced high-strength steel prior to any melting of Zn. Their formation and increasing presence with temperature correlates with severe mechanical degradation. These findings provide consistent evidence that the solid-state formation of Fe-rich Fe-Zn intermetallic phases constitutes an early contributing step to LME in galvanized high-strength steels.
Interlaminar fracture under mode II-dominated loading is a critical damage mechanism in fibre-reinforced composite laminates, but conventional edge-based measurements cannot resolve non-planar crack growth in multidirectional architectures. Here, in situ X-ray computed tomography is combined with a bespoke four-point bending rig to visualise delamination in carbon-fibre-reinforced laminates. A unidirectional 0° laminate showed planar crack growth confined to the original interface, enabling conventional fracture-toughness interpretation. By contrast, a ±45° laminate exhibited successive crack-migration events, producing a non-planar zig-zag fracture path involving interlaminar fracture and intralaminar splitting. These observations show that crack propagation in multidirectional laminates is non-self-similar and that conventional data-reduction methods may not yield a physically meaningful interlaminar fracture toughness. Instead, the measured response represents an apparent global fracture resistance influenced by laminate architecture, crack-front distortion, and crack-path evolution.
Aluminum alloys are widely used in research reactor systems, yet the mechanisms governing irradiation‑induced degradation remain poorly understood. Here, we combine conventional displacement cascade-overlap molecular dynamics simulations with an accelerated iterative kinetic approach (IKA) to investigate defect evolution in single‑crystal Al subjected to 50 keV He irradiation. Benchmarking shows that IKA reproduces the essential defect kinetics of cascade simulations while enabling access to substantially higher accumulated damage. By extending the IKA to higher damage levels, we identified three distinct regimes governing radiation-induced degradation in Al: recombination-driven annihilation, defect accumulation, and sink-controlled absorption. At higher damage, Frank loops dissociate into Shockley partials and stair‑rod loops, ultimately driving the nucleation and growth of stacking‑fault tetrahedra (SFTs). These transformations progressively convert mobile defects into SFTs. Ultimately, the synergistic effect of interstitial and vacancy loops, and SFT increases irradiation hardening in Al at 300 K. This work provides insight into irradiation‑induced degradation in aluminum reactor materials.
This study examines the long-term devitrification of selenium over 25 years, examining structural, thermal, electrical, and mechanical changes. XRD analysis reveals an increase in crystallinity, accompanied by an apparent reduction in coherent diffraction domain size (CDDS) from 83.1 ± 4.1 nm in the fresh sample to 30.1 ± 1.5 nm after 25 years of ageing, accompanied by an increase in microstrain and dislocation density. The surface texture reveals surface roughening, microvoids, and cracks, indicating degradation. A narrowed glass transition and dual crystallization peaks suggest phase separation; the crystallization activation energy increases with ageing. The augmentation in ε‘ to 29.8 and ε“ to 14.04 in aged samples is due to dipolar and space charge polarization. Microhardness decreases from 84.6 to 45.6 kgfmm−2, accompanied by an increase in microvoid volume and a reduction in modulus and yield strength. Hence, the slow devitrification as a sign of physical ageing in selenium glasses leads to structural relaxation, increased crystallinity, and compaction at the atomic scale, resulting in improved thermal and electrical behavior but compromised mechanical resilience. These insights are crucial for predicting the long-term performance and stability of chalcogenide glasses in technological applications.
Earthen heritage is highly vulnerable to water-induced deterioration, particularly under increasingly intense rainfall events. This study evaluates the effectiveness of hydrated lime (HL) and magnesium oxide-hydrated lime (MgO-HL) stabilization in improving the hydric durability of adobe prepared from earthen material collected at the Campo del Pozzo archeological site, Nazzano, Italy. Adobe specimens with different stabilizer dosages were evaluated through accelerated rainfall simulation, capillary water absorption, and 72 h immersion tests, while mineralogical and microstructural changes were investigated using X-ray diffraction and FE-SEM-EDS analyses. All stabilized samples revealed enhanced resistance to water-induced degradation compared with untreated material, with the best performance achieved by the 15 wt% HL sample and the hybrid formulation containing 10 wt% MgO + 10 wt% HL. These treatments reduced rainfall erosion, limited capillary water uptake, and preserved sample integrity during immersion. Stabilization promoted the formation of C-S-H, C-A-H, and C-A-S-H phases, while Mg-bearing hydrates promoted pore-filling and interparticle cementation. The improved durability is attributed to reduced clay mineral expandability, precipitation of secondary hydrate phases, and aggregation of clay-sized particles. These results demonstrate that HL and MgO-HL stabilization can provide mineralogically compatible strategies for enhancing the durability and resilience of earthen heritage materials.
