This study investigated the role of grain orientation in the internal corrosion and hot salt stress corrosion cracking (HSSCC) behaviors of Ti60 under a humid NaCl-rich environment at 600 degrees C. By combining SEM morphology with grain orientation results, it is demonstrated that grain orientation controls the pathways of NaCl-induced internal corrosion and HSSCC. The internal oxides grow parallel to the (0001) basal planes within the alpha grains, proving high corrosion susceptibility along these planes. This crystal structure-dependent corrosion susceptibility further controls HSSCC behavior. Cracks propagate transgranularly along directions parallel to the basal planes, and the propagation mode between grains is governed by the difference in basal plane orientation.

Conventional protective coatings tend to fail prematurely under the extreme thermal-salt-steam coupled conditions typical of marine and aero-engine operating environments. Here, we present a strategy to enhance corrosion resistance by fabricating Cr2AlC MAX-phase coatings with a strong (1120) prism plane texture, achieved via synchronized pulsed HiPIMS deposition. As a control, a texture-free, equiaxed Cr2AlC coating was also prepared. Following a 5 h exposure to a simulated thermal-salt-steam environment at 600 degrees C, the textured coating demonstrated exceptional corrosion resistance, forming a corrosion scale that was only one-third the thickness of its equiaxed counterpart. Mechanistic investigations revealed that the Prism-plane coating orientation accelerates the formation of a dense, uniform amorphous Al2O3 scale, which acts as an effective barrier against corrosive species. These findings underscore the pivotal role of crystallographic orientation in environmental durability, offering a pathway to design high-performance MAX-phase coatings for extreme service conditions.

In this work, MAO/Cr bilayer coatings were deposited on Zr alloys by combining micro-arc oxidation (MAO) and high-impulse-power magnetron sputtering (HiPIMS) techniques. The coating exhibited outstanding resistance to electrochemical and high-temperature steam corrosion. As the surface defects of the MAO interlayer increased the nucleation sites of Cr grains, it refined the grain size of the Cr top layer, which could promote the growth of passive film in lithium borate aqueous solution and enhance its corrosion resistance. Moreover, under the simulated loss-of-coolant accident (LOCA) scenario, the MAO/Cr bilayer coating exhibited a weight gain roughly 34.9 % lower than the Cr coating after oxidation for 90 min. This was primarily due to the MAO interlayer inhibiting interdiffusion at the coating-substrate interface and reducing the rapid diffusion paths for oxygen in the residual Cr coating during oxidation.

Selective laser melting of Ti6Al4V offers rapid production but the formation of coarse prior-β columnar grains is detrimental to mechanical properties. This study explores an in-situ strategy using a dual-laser scanning sequence: a low- power (10 W) pre-scan followed by a high-power (190 W) main scan (Re10W). Compared to the single 190 W scan, the Re10W strategy improves the ultimate tensile strength by 6%, and elongation by38%. Relative to the same power remelted condition (Re190W), the Re10W samples also exhibit 25% higher elongation while maintaining better strength, confirming that the property enhancement originates from the duplex thermal sequence rather than mere remelting. Microstructural characterization reveals that the low-power pre-scan refines both the prior β grain size (from 150 μm to 100 μm) and the α' martensite lath width (from 0.39 μm to 0.33 μm). This synergy is attributed to the pre-scan refining the prior β grains and enabling dislocation rearrangement into substructures, as evidenced by refined microstructures, reduced KAM values and increased substructured fraction. These modifications effectively relieve stress while maintaining strength, showcasing an efficient method for producing high-performance Ti6Al4V components without extra post-processing.

It is greatly challenging to monitor real-time dynamic evolution of pre-catalysts in complicated redox reactions, and there is, therefore, still a lack of profound understanding into their behavior mechanisms. Herein, we reveal a dynamic dual-evolution mechanism of Co-CoO heterostructure catalyst in Li-S batteries through combining a series of in situ characterization techniques. In situ phase transformation of partial CoO into CoS2 couples with synchronous crystal-plane slip, and the crystal-plane slip induced by lattice distortion continuously exposes new active sites. The dynamic dual-evolution of heterostructure catalysts broadens the catalytic selectivity toward sulfur redox reactions, establishes a unique bidirectional catalytic reaction pathway for sulfur conversion, and realizes controllable full-range reaction kinetics manipulation in Li-S batteries. Eventually, Li-S batteries exhibit a low capacity decay of 0.035% per cycle for 1000 cycles at 1.0 C, and multilayered Li-S pouch cells harvest an ultrahigh energy density of 362.7 W h kg-1 even under a high areal loading of 8.33 mg cm-2. This work provides direct atomic-level evidence to real-time dynamic evolution of catalysts, deepens insights into the catalyst evolution mechanism, and inspires new design routes for developing low-cost and high-energy-density Li-S batteries.

The anti-corrosion and electromagnetic wave-absorbing (EWA) performance evolution of series carbonyl iron (CIP) microwave absorbing coatings with different mass fractions have been investigated in 3.5 wt.% NaCl solution. The results reveal that NaCl solution penetrates in the coatings, subsequently triggering CIP surface corrosion and epoxy resin hydrolysis, both of which reduced the coating's anti-corrosion properties and influenced the wave absorption abilities. The NaCl solution and corrosion products synergistically promote the conductivity and interfacial polarization of the coatings, thus affecting the attenuation ability and impedance matching of the coatings to electromagnetic wave. The effects of various defects introduced by adding CIP fillers or coatings have been discussed according to the analysis of anti-corrosion and wave absorption properties on serious CIP filler coatings.

The Ti₂AlC MAX phase coating is expected to become one of the potential protective coatings for aircraft compressor blades because of its excellent resistance to thermal corrosion. Considering the stresses imparted to blades by structural design, it is urgent to elucidate the mechanism by which stress influences the interfacial corrosion behaviour of Ti₂AlC coatings. In this paper, a four-point bending beam stress loading method was employed to investigate the corrosion behavior of TiAl/Ti2AlC coatings with solid salt deposition under 600 °C + water vapor environments. Results show that stress caused an increase in the thickness of the corrosion product film and the number of cracks within the TiAl/Ti₂AlC coatings, following linear and parabolic laws, respectively. The applied stress promotes the internal diffusion of Cl and O along the crack path towards the Ti₂AlC side of the TiAl-Ti₂AlC interface within the coating. The synergistic effect of Cl cycling and the activation-oxidation mechanism accelerates the depletion and outward migration of Al, leading to cracking initiation in Al-depleted zones, fracture at the TiAl-Ti₂AlC interface, and coating failure.

Lithium-sulfur batteries (LSBs) are still plagued by major challenges of the shuttle effect of polysulfides and the slow redox kinetics through years of rapid development. Herein, a CoS2-WS2/GNC heterostructure is designed to modify the separators and provide an efficient strategy to tackle these challenges. This heterostructure combines the strong adsorption of CoS2 for lithium polysulfides (LiPSs) and the high catalytic activity of WS2 for LiPSs, generating a synergistic effect that jointly achieves the "capture-adsorption-catalysis" of LiPSs, effectively alleviating the problems of polysulfide shuttling and slow redox kinetics. Therefore, the LSBs assembled with the CoS2-WS2/GNC modified separator delivers an initial discharge specific capacity of 1079 mA h g- 1 at 1C with a capacity fading 0.055 % per cycle during 1000 cycles. Impressively, the battery can provide a reversible discharge specific capacity of 423 mA h g- 1 even at a higher current density of 5C, with a capacity retention rate of 65 % after 600 cycles. This work provides new ideas for the design of functionalized separators that combine efficient adsorption and catalysis.

Polypropylene (PP) nonwoven fabrics offer many advantages, such as interconnected microstructures, flexibility, and chemical stability. However, their intrinsic hydrophobicity severely restricts applications in oil-water separation. In this work, inductively coupled plasma-enhanced chemical vapor deposition (IC-PECVD) was employed to endow PP nonwoven fabrics with superhydrophilic-underwater superoleophobic properties. After hexamethyldisiloxane deposition, a subsequent 5 min oxygen plasma treatment transformed the fabric surface from highly hydrophobic (>130 degrees) to superhydrophilic (complete wetting), and from lipophilic (similar to 60.3 degrees) to underwater superoleophobic (similar to 151 degrees). The fiber surface evolved progressively from smooth to conical structure with high roughness and distributed different sizes of nanoparticles, while hydrophilic oxygen-containing polar functional groups were introduced. Importantly, the coating designed by this unique combination improved the crosslinking degree of the fiber surface, stabilized hydrophilic hydroxyl, carboxyl and other functional groups, which greatly improved the problem of plasma aging effect, maintaining high stability in air over 260 days. The long-term stability and cyclic oil-water separation tests were carried out on the pre-wetted modified nonwoven fabrics. The fabrics consistently exhibited an oil-water separation efficiency exceeding 99.0%, along with longterm stability, chemical resistance and self-cleaning capability. These results are broadening the application of modified nonwoven fabrics in the field of actual oil-water separation.

The reliability of titanium alloy welded joints is critical to the service safety of deep-sea engineering systems. The welding thermal cycle generates complex microstructures in Ti-6Al-4V, resulting in pronounced mechanical and electrochemical heterogeneity across joint regions. Herein, in-situ electrochemical testing was conducted to investigate stress corrosion cracking (SCC) behavior in distinct weld zones under hydrostatic pressure. Results reveal that hydrostatic pressure accelerates electrochemical reactions and enhances the SCC susceptibility-most severely in the heat-affected zone. This heightened vulnerability stems from the transformed beta phase and lamellar secondary alpha phase, which promotes strain localization and impairs repassivation capability. This work presents the evidence of region-dependent-SCC susceptibility in Ti-6Al-4V welds under hydrostatic pressure, offering essential experimental insights for the safety assessment and welding optimization in deep-sea titanium structures.

An investigation was conducted into the corrosion mechanism of 321 stainless steel (SS) without and with 10% strain in a simulated secondary circuit steam pipeline environment of nuclear-powered vessels, which involved exposure to intermediate temperature water vapor (480 degrees C, 95%vol) and normal temperature dilute salt solution (30 degrees C, 0.5 wt% NaCl). The results indicate that ferrite in 321 SS is the vulnerable site for alternating corrosion. Localized corrosion along the ferrite is caused by the combined effects of oxidation and electrochemical reactions. Residual NaCl particles from a 30 degrees C dilute salt solution undergo an oxidation reaction with water vapor at 480 degrees C, which destroys the protective oxide film, leading to the formation of a Cr-depleted zone where the Cr content in ferrite becomes lower than that in austenite. In the 30 degrees C dilute salt solution, the ferrite in the Crdepleted zone exhibits a higher self-corrosion current density, and the galvanic effect between the two phases in this zone further promotes the dissolution of ferrite, thereby leading to localized corrosion. Under an applied strain of 10%, the difference in Cr content between the two phases increases. This both enhances the difference in icand intensifies the galvanic effect between the phases, thereby accelerating localized corrosion.

This study employed electrochemical impedance spectroscopy (EIS) to investigate the evolution of pore structures within the NaCl-induced corrosion-affected zone. When a small amount of NaCl was deposited, mesopores within the matrix initially formed and were subsequently repaired by the growth of oxides. The amount of NaCl promoted the formation of mesopores by accelerating the destruction of the oxide layer and Cl-induced active corrosion. A transmission line model (TLM) was proposed for the studied porous titanium electrode. The high-frequency slope of the Nyquist plot can monitor the mesopores formation, which are the positions for stress corrosion crack initiation in titanium alloys exposed to NaCl-containing environments. The angle between the Nyquist plot and the real axis was less than 31° when the abundant mesopore formed.

ABSTRACT Electrical contact materials for advanced power transmission and electromagnetic systems must simultaneously provide high electrical conductivity, arc‐erosion resistance, and tribological stability under extreme electro‐thermo‐mechanical conditions. Herein, Cr 2 AlC and Cu‐doped Cr 2 AlC (Cr 2 AlC‐Cu) coatings were deposited on 7075 aluminum alloy via hybrid arc‐magnetron sputtering followed by low‐temperature annealing at 400°C. With increasing Cu content (0‐9.1 at.%), the coating microstructure evolves from single‐phase Cr 2 AlC to a dual‐phase architecture consisting of Cr 2 AlC and Al 4 Cu 9 . All coatings exhibit high hardness values (18.8‐21.2 GPa), originating from grain refinement and amorphous‐nanocrystalline structures induced by low‐temperature annealing. The Cu‐rich coating demonstrates the lowest electrical resistivity (119 µΩ·cm) and superior resistance to arc erosion. This performance enhancement is attributed to Cu‐assisted Al‐Cu interdiffusion, which accelerates in situ MAX‐phase crystallization and promotes the formation of conductive interfacial networks under Joule heating, establishing a positive feedback mechanism that stabilizes electrical transport and suppresses arc erosion. Moreover, the formation of an adherent Cu transfer layer transforms the frictional interface into a Cu‐Cu sliding contact, effectively reducing friction and preventing adhesive wear of the aluminum substrate. These synergistic effects activate a self‐adaptive crystallization and lubrication mechanism during service, highlighting Cu‐doped Cr 2 AlC coatings as promising candidates for next‐generation electrical contact applications.

Amorphous carbon (a-C) coating can effectively reduce wear of the counterpart PEEK components in engineering equipment. While, the tribological performance of both a-C and PEEK demonstrates pronounced sensitivity to ambient atmosphere. Here, tribological behaviors of a-C/PEEK were compared under various environments including atmosphere, vacuum, and O2, the interfacial tribo-chemical reaction was discussed from experimental investigation and atomic-level simulations. Results show that, oxygen content is one key factor to influence interfacial tribo-chemical reaction and wear mechanism for a-C/PEEK pair. Under ambient atmosphere and O2, oxygen molecules break molecular chains of PEEK, even bond or absorb on the a-C under higher oxygen content, which can hinder the formation of the transfer film and result in elevated COF and worse wear of PEEK.

Currently, the stability analysis of the beta phase in titanium alloys at high temperatures is mostly speculative or relies on simulations. In contrast, this study conducted in-situ high-temperature experiments on TC21 samples using a scanning electron microscope (SEM) equipped with a high-temperature stage. A slow temperature ramp rate (0.5 degrees C/s) was applied to induce the phase transformation from alpha to beta and back to alpha in the titanium alloy. Real-time secondary electron images were captured, and electron backscatter diffraction (EBSD) data were recorded at various temperatures. The results indicate that during the alpha to beta phase transformation, nucleation and growth of the beta phase occur at both the alpha/beta phase boundaries and within the alpha/alpha grain boundaries. Grain boundary migration was observed after the alpha phase had fully transformed into the beta phase. During the beta to alpha phase transformation, it was obversed that alpha variants initially nucleate near the beta grain boundaries (GBs) and subsequently grow inward into the alpha grains. Additionally, alpha variants were observed to nucleate at the alpha/beta phase boundaries, resulting in a distinct variant selection pattern, a phenomenon not previously reported.

High-entropy materials possess high hardness and strong wear resistance, yet the key bottleneck for their practical applications is the poor corrosion resistance in harsh environments. In this work, the highentropy nitride (HEN) coatings of (MoNbTaTiZr) 1- x N x ( x = 0-0.47) were fabricated using a hybrid direct current magnetron sputtering technique. The research focus was dedicated to the effect of nitrogen content on the microstructure, mechanical and electrochemical properties. The results showed that the as-deposited coatings exhibited a typical body-centered cubic (BCC) structure without nitrogen, while the amorphous matrix with face-centered cubic (FCC) nanocrystalline grain was observed at x = 0.17. Further increasing x in the range of 0.35-0.47 caused the appearance of polycrystalline FCC phase in structure. Compared with the MoNbTaTiZr metallic coating, the coating containing nitrogen favored the high hardness around 13.7-32.4 GPa, accompanied by excellent tolerance both against elastic and plastic deformation. Furthermore, such N-containing coatings yielded a low corrosion current density of about 10 -8 -10 -7 A/cm 2 and high electrochemical impedance of 10 6 Q cm 2 in 3.5 wt.% NaCl solution, indicating the superior corrosion resistance. The reason for the enhanced electrochemical behavior could be ascribed to the spontaneous formation of protective passive layers over the coating surface, which consisted of the dominated multi-elemental oxides in chemical stability. Particularly, noted that the (MoNbTaTiZr) 0.83 N 0.17 coating displayed the highest hardness of 32.4 +/- 2.6 GPa and H/E ratio at 0.09, together with remarkable corrosion resistance, proposing the strongest capability for harsh-environmental applications required both good anti-wear and anti-corrosion performance. (c) 2024 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Solid lubricating coatings play a crucial role in preventing friction and wear failure of the hot-end sliding components in aviation engines. In this study, VAlN/Ag multi-layer coatings with excellent interfacial matching were fabricated using a hybrid magnetron sputtering technique. The type and energy of discharge plasmas were analyzed to comprehend their effects on depositing coatings. The coatings exhibit self-adaptive lubrication properties during the designed consecutive friction with stepwise heating from 25 degrees C to 650 degrees C. The microstructure evolution during early friction facilitates sufficient tribo-chemical reaction at 650 degrees C, leading to the formation of a distinctive "ball-on-rail" structure that significantly reduces friction coefficient. Based on the first-principles calculations, it was found that the bond energy of Ag-O is lower than that of V-O in both AgVO3 and Ag3 VO4 , which promotes slipping along the (110) crystal plane and contributes to exceptional tribological properties. The fatigue wear failure mechanism of hard coatings under the thermal-force coupling effects has been elucidated, alongside an exploration of consecutive tribology mechanism at atomic scales over a wide temperature range. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

The corrosion behavior and rust layer structure of two high-Mn austenitic steels (Fe- 18.5Mn-7Cr- 0.6C and Fe- 18.5Mn-7Cr- 0.6C- 0.2 N) were investigated in a simulated industrial atmosphere. N alloying improved the corrosion resistance, primarily through microstructural modifications in the rust layer structure. N alloying enhanced Cr enrichment (mainly as Cr2O3) in the inner rust layer, resulting in greater thickness and compactness. Additionally, N alloying refined the alpha-FeOOH grains and increased the alpha-FeOOH/gamma-FeOOH ratio, improving the protective properties of the outer rust layer.

High-entropy ceramics (HECs) are a novel category of multicomponent ceramics featuring significant atomic-scale disorder. This unique structure preserves the intrinsic properties of individual elements while enabling their interactions to generate intriguing phenomena. In this study, single-phase and dual-phase (TiVCrNbTa)O-2 high-entropy oxide ceramics (HEOs) were fabricated via a straightforward sintering process. The synthesis of single-phase HEOs with a pure rutile structure was achieved at 1400 degrees C by altering the sintering atmosphere from air to argon. The single-phase (TiVCrNbTa)O-2 HEOs exhibited remarkable dielectric properties, with dielectric constants (similar to 5) and dielectric loss attain the order of 10(-3) in the frequency range of 2-4 GHz. The dual-phase (TiVCrNbTa)O-2 HEOs also have approximate dielectric properties and exhibit excellent thermal stability from room temperature to 1200 degrees C under the air atmosphere. A new single-phase and dual-phase HEOs was successfully synthesized, and their dielectric properties as well as thermal stability meet the requirements of wave-transparent materials.