Conventional aluminum matrix composites typically rely on hard secondary phases to improve strength, hardness, and wear resistance via second-phase strengthening and load-transfer mechanisms. However, in Al/steel tribopairs, such strategies focused solely on hardening the Al matrix composites often exacerbate abrasive wear on the steel counterpart, accelerating surface degradation and leading to premature system failure. To overcome this limitation, we propose a novel sepiolite-mediated reinforcement strategy: natural sepiolite (Spl) was incorporated into agglomerated Al powder and consolidated via spark plasma sintering to fabricate Spl/Al composites. The design exploits a tribo-triggered self-healing mechanism involving wear-induced dehydroxylation and exfoliation of sepiolite, release of reactive oxygen species, bidirectional transfer of metallic wear debris, and coupled tribochemical–mechanical reactions. Orthogonal SRV reciprocating sliding tests show that, compared with the pure Al/steel tribopair, the composite reduces wear volume by 7.59–47.68% and decreases the steel counterpart’s wear scar diameter by 1.25–34.3%, while the coefficient of friction is lowered by 4.85–58.88%. A self-healing tribolayer forms in situ on the contact surfaces, comprising hard phases (Al2O3, SiO2, SiC, MgSiO3, Fe3C, AlFe3) and lubricious components (graphite and unreacted sepiolite), which together confer an optimal balance of mechanical robustness and solid lubricity. This transforms the wear mode from direct Al/steel contact to sliding between conformal self-healing tribolayer, thereby significantly enhancing the overall tribological performance and durability of the tribopair

Titanium alloys are widely used in marine engineering but suffer from poor hardness and wear resistance, often leading to severe cavitation erosion. Conventional single-layer coatings struggle to balance hardness and toughness. In this work, a strong-tough integrated composite coating was fabricated on Ti–6Al–4 V alloy via laser cladding, featuring a heat-treated HT-Ni51.7Ti42.3Si4(YF3)2 tough bottom layer and a hard in-situ TiC-reinforced [Ni51.7Ti42.3Si4(YF3)2]C top layer. The microstructure, phase composition, and tribological and cavitation erosion performance were systematically investigated. The coating exhibits a dense, crack-free gradient structure. The top layer consists of NiTi (B2), NiTi2, and in-situ TiC, while the bottom retains a NiTi (B2), NiTi2, and Ti5Si3 eutectic structure. The average microhardness of the top, transition, and bottom zones reaches 1187 HV0.3, 727 HV0.3, and 456 HV0.3, respectively. The composite coating demonstrated exceptional wear resistance, reducing wear weight loss by 43.7% and 44.8% under 5 N and 15 N loads, respectively, compared to the single-layer coating. Concurrently, the specific wear rates of the LSC/HT composite coating were determined to be as low as 3.10 × 10−4 and 3.94 × 10−4 mm3·N−1·m−1 under 5 N and 15 N. Furthermore, The cavitation weight loss was reduced by 51.85%, with cavitation resistance increasing by 2.05 times. The coating achieves synergistic external hardness and internal toughness: TiC improves wear and cavitation resistance, while the bottom NiTi enables stress-induced martensitic transformation for energy dissipation. This work provides a novel, effective strategy for developing high-performance protective coatings for marine titanium alloy components.

The demand for the service performance of Zr alloys as conventional structural materials in extreme operating conditions is on the rise. The utilization of pre-oxidation technology to develop the high-entropy alloy (HEA) coating with a pre-oxidized layer on Zr alloy holds great potential for expanding the application scope of Zr alloy in the nuclear power field. Herein, this work aims to design a HEA coating system incorporating easily oxidizable the rare earth elements (Gd/Nd). By employing laser cladding and pre-oxidation technologies, the Al0.2Nb-TiV0.1W0.5Zr0.3-8 wt% Gd/Nd HEA coatings containing a pre-oxidized layer on the Zr alloy surface were successful fabricated. The pre-oxidation layer with rare earth elements as the main component exhibits superior compactness. The formation of this pre-oxidation layer can significantly enhance the corrosion resistance of the HEA coating in H3BO3-LiOH solutions and its high-temperature oxidation resistance. This work provided valuable theoretical basis for design of HEA coating system and structure with high performance on Zr alloy under harsh conditions.

In this study, we propose a strategy for the in-situ formation of array Nitride phase to enhance the wear performance of eutectic high-entropy alloy coating. At both room temperature and 600 degrees C, the wear resistance of the coating significantly surpasses that of the substrate. The wear volume loss of this coating at RT and 600 degrees C are 1.79 % and 0.33 % of the Ti-6Al-4V alloy. Characterization through SEM and EBSD revealed that no plastic deformation occurred in the sub-surface of the coating. Instead, a substantial number of dislocations and subgrain boundaries were distributed within the gaps of the Nitride phase. This coating and technology hold promise for applications in wear-resistant protection for titanium alloys.

To investigate the impact of oxidation behavior on tribological properties of NiCrFe/Al/BN abradable seal coatings (ASCs), NiCrFe/Al/BN ASCs were prepared by thermal spraying. The oxidation behaviors at 650 degrees C for 192 h and the tribological properties of oxidized coating were discussed. The effect of oxidation on the tribological properties of the coating was that oxidation promoted the formation of hard oxides on the surface of the coating, aggravated the damage to the wear ball, and thus reduced the tribological properties of the coating. Specifically, the formation of theta-Al2O3 and Cr2O3 oxidation products the friction increased coefficient and grinding ball weight loss of oxidized coatings. In the initial 72 h, needle-like theta-Al2O3 and small block-like Cr2O3 formed on the surface of coatings. Over the subsequent 120 h, only Cr2O3 continued to grow, attributed to the depletion of aluminums on the surface. Eventually, the large block-like hard spinel Cr2O3 and needle-like theta-Al2O3 covered coatings, resulting in an increase in the friction coefficient of the oxidized coatings, as well as intensified weight loss on the grinding ball. Additionally, the inner oxidation was concentrated in the pores. The oxidation growth of alumina inside the coating will fill the pores inside the coating, thereby increasing the hardness of the coating. In summary, long-term oxidation would cause the NiCrFe/Al/BN ASCs to harden and intensify wear on the grinding ball, indicating that high-temperature oxidation weakened the abradability of the NiCrFe/Al/BN ASCs. Future research on novel NiCr-based ASCs should prioritize enhancing oxidation resistance as a key focus.

Thin-walled stiffened aluminum alloy structures are key load-bearing components of aerospace devices and other carrier equipment owing to their high strength, lightweight nature, and reliability. However, fatigue is a primary failure mode in them during stable operation. This study combined in situ fatigue using synchronous X-ray tomography, fracture morphology observation, and finite element simulation to analyze the failure behaviors of the thin-walled stiffened structure. The monitoring of the fatigue process and observation of fracture morphology indicated that fatigue crack initiation was affected by the coupling of the stress concentration and second-phase. It was indicated by FIB-TEM that the latter is caused by the plastic mismatch between phases and the increase in internal residual stress due to the accumulation of dislocations. Furthermore, the fatigue failure behavior across each zone of the thin-walled stiffened structure was discussed in detail to deduce the fatigue failure mechanism. Using SolidWorks for solid modeling and Abaqus-Franc3D for fatigue crack propagation (FCP) analysis, the crack propagation morphology, stress intensity factor (K), and fatigue life variation were determined to analyze changes in the mechanical properties at the crack tip during the fatigue damage process. Results showed that stiffened plates impeded FCP.

Improving wear resistance without sacrificing impact toughness remains a persistent challenge for protective coatings. To overcome this challenge, this study successfully fabricated a FeCoNiCr-WC gradient coating that combined external wear resistance with internal toughness. Microstructural analyses indicated that the coating features depth-dependent gradients in both the volume fraction of hard phases (WC particles and M3W3C) and the grain size (M3W3C and FCC). The gradient coating exhibited a surface hardness of 878.02 HV0.3 and a wear rate of 3.47 ± 0.22 × 10−6 mm3/(N·m). Compared with the homogeneous FeCoNiCr+60 wt%WC coating, the gradient coating exhibited a 69.3% enhancement in impact toughness (128.3 ± 6.1 J/cm2). These findings provide a theoretical basis for the design of protective coatings that synergistically combine wear resistance and toughness.

Refractory high-entropy alloys （RHEAs）， owing to their exceptional high-temperature properties， show great potential for use in extreme environments such as aerospace systems. However， the inherent complexity of their multicomponent systems poses significant challenges to the efficiency of conventional alloy design methods. Although additive manufacturing （AM） overcomes some limitations of traditional fabrication routes， its intrinsic non-equilibrium solidification behavior and complex process-parameter space introduce new challenges in microstructural control and property optimization. In this context， machine learning （ML） offers a data-driven paradigm for uncovering the intricate composition-structure-property relationships in RHEAs and provides a powerful tool for intelligent materials design. This review systematically summarizes the latest advances in the application of ML to RHEAs， with particular focus on key issues in AM scenarios. On the one hand， the roles of ML in phase prediction， strength and ductility optimization， and hardness design are discussed. On the other hand， ML-enabled strategies for process-parameter optimization， defect mitigation， and microstructural tailoring in AM are thoroughly analyzed. Despite notable progress， several challenges remain， including the scarcity of AM-specific datasets， the limited generalization capability of process-property models， and the insufficient integration of physical mechanisms. Therefore， establishing standardized databases oriented toward additive manufacturing， developing machine learning models integrated with physical constraints， and constructing an integrated process-microstructure-property optimization framework are key directions for promoting the transition of refractory high-entropy alloys in the field of additive manufacturing from “printable” to “designable”.

Supersonic fine particle bombardment (SFPB) pretreatment was applied to 10CrNi2Mo3Cu2V aerospace gear steel using La2O3-, Yb2O3-, and Sm2O3-doped blasting media, followed by vacuum carburizing in a vacuum carburizing furnace. The surface morphology, phase constitution, carbide evolution in the carburized layer, and tribological properties were systematically characterized. Combined with first-principles calculations, the mechanism by which different rare-earth regulate carbon adsorption on the surface and subsequent subsurface migration was investigated. The underlying mechanisms were analyzed through lattice expansion, C adsorption energy on the Fe surface, and local charge transfer. The experimental and computational results indicate that La doping weakens C adsorption, reducing the adsorption energy from −9.067 eV for pure γ-Fe to −7.655 eV and lowering the vertical position of the C atom from z = 0.593 on the pure Fe(110) surface to z = 0.578, thereby facilitating carbon migration into the deeper region and producing the largest effective case depth of 1.18 mm. In contrast, Yb doping enhances the adsorption energy to −12.917 eV and shifts the C atom upward to z = 0.635, promoting near-surface carbon trapping and fine carbide precipitation; the fraction of carbides smaller than 0.2 μm reaches 64.38%, resulting in the best wear resistance. The effect of Sm doping lies between those of La and Yb. These findings provide theoretical guidance for the selection of rare-earth carburizing promoters and the microstructural regulation of carburized aerospace gear steels.

This study investigates the tribological and electrochemical corrosion behavior of laser-clad nickel-aluminum bronze (NAB) coatings reinforced with WC particles (0, 8, 16 wt.%). Through microstructural characterization and phase analysis, it was found that in the NAB coating containing 16% WC, the WC particles and carbides were uniformly distributed, serving as a reinforcing scaffold. During the friction and wear process, they effectively reduced the contact area between the counter ball and the NAB matrix to a certain extent, smoothing the wear process and resulting in a more stable friction coefficient. Electrochemical testing demonstrates that WC addition significantly enhances corrosion resistance: NAB + 8%WC exhibits a low corrosion current density (icorr), the highest polarization resistance, and the densest protective film. The dual mechanisms-grain boundary blocking and ion channel obstruction-reduce selective Al/Fe leaching and minimize Cl- penetration. The 8% WC formulation optimizes the electrochemical performance, providing excellent corrosion resistance in a simulated marine environment.

Metal-ceramic composite coatings are widely employed across industries; however, the effects of high-temperature environments on their microstructural evolution and corrosion behaviour remain inadequately understood. In this study, a NiCrMoAl-Al2O3 composite coating was fabricated via plasma-enhanced high-velocity arc spraying and subsequently subjected to heat treatment at 800 degrees C for 2 h. The microstructural evolution and corrosion resistance of the coating before and after heat treatment were analysed using multiple characterisation techniques. In addition, corrosion products and elemental distributions were characterised via transmission electron microscopy, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. Electrochemical corrosion testing revealed that the corrosion potential of the coating shifted positively after heat treatment, whereas the corrosion current density decreased. In addition, the maximum corrosion depth of the heat-treated coating was only similar to 40% of that of the untreated coating, and a uniform oxide layer formed on the coating surface after corrosion. The enhanced corrosion resistance was primarily attributed to the increased density of the coating after heat treatment and the formation of internal oxide phases and a dense surface barrier layer enriched in Cr2O3 and Al2O3. Overall, this study elucidates the microstructural evolution and corrosion-protection mechanisms of metal-ceramic composite coatings under high-temperature service conditions and provides useful guidance for their engineering application and process optimisation.

This study utilizes multi-arc ion plating (MAIP) to construct AlCrTiNbZr film and (AlCrTiNbZr)N film on TC11 titanium alloy and silicon wafers. The phase composition, microstructure, mechanical properties, tribological performance, and erosion resistance of the films were characterized. The findings indicate that the AlCrTiNbZr film exhibits a single-phase BCC structure. Nitrogen treatment results in the development of FCC nitride phases, yielding a dual-phase composite structure comprising both BCC and FCC. The introduction of nitrogen significantly enhances the mechanical properties, with the nano-hardness of the (AlCrTiNbZr)N film being nearly 1.85 times higher than that of the AlCrTiNbZr film, while the elastic modulus increases from 235.93 f 5.5 GPa to 375.34 f 4.1 GPa. Additionally, the residual stress rises from 293.9 f 6.9 MPa to 353.8 f 5.7 MPa. The (AlCrTiNbZr)N film demonstrates exceptional tribological performance and erosion resistance, with the wear rate is 1.65 f 0.15 x 10-14 m3 N- 1 m-1, representing a remarkable 96.40 % reduction compared to the TC11 titanium alloy substrate. The erosion rates in 30 degrees and 90 degrees impact angles are reduced by 89.78 % and 83.22 %, respectively.

Although body-centered cubic (BCC) duplex high-entropy alloys (DHEAs) show promising high-temperature performance, their room-temperature brittleness and insufficient ductility limit practical applications. Herein, we report a novel in-situ synthesized FeCoCrNiAl DHEA coating with a "single-double-single" phase-gradient architecture (BCC -> BCC + FCC -> FCC) fabricated via laser cladding under optimized parameters (laser power: 1500-1800 W; scanning speed: 5-15 mm/s). The coating exhibits exceptional oxidation resistance at 800 degrees C, with a negligible mass gain of 0.09 mg/cm2 after 200 h, owing to the formation of a dense Al2O3/Cr2O3 layer. Moreover, it demonstrates outstanding tribological performance with a low friction coefficient of 0.2617 and a wear rate of 9.23 x 10-7mm3/(N & sdot;m), alongside remarkable erosion resistance (erosion rate: 5.3 x 10-4g/ (cm2 & sdot;s)) under high-temperature conditions. The gradient structure synergistically enhances mechanical robustness and interfacial cohesion, effectively resolving the strength-ductility trade-off. This work provides a strategic design pathway for developing high-performance DHEA coatings suitable for extreme thermal--mechanical environments.

Metallic glasses are widely investigated for corrosion due to their compositional homogeneity. To mitigate the deficiency of low plasticity in metallic glasses and expand their application scenarios, this study designed the novel Fe52Ni5Nb5Cr16Mo5B12Si5 metallic glass coatings. The systematic investigation into crack and pore formation established a direct correlation between the HVAF process parameters, key coating quality indicators (compactness and amorphous phase content), and corrosion resistance, leading to the successful fabrication of dense coatings free of macroscale defects. During corrosion, the passive film formation follows a sequential process. First, Si oxidation establishes a primary film matrix. Then, the subsequent incorporation and accumulation of Cr2O3 within this matrix plays a critical role in densifying the passive film. This densification process is key to improving the film’s barrier property against Cl−. Conversely, localized pitting primarily results from the reduction of Mo6+ to Mo4+, which compromises the film’s local stability.

Conventional aluminum matrix composites typically rely on hard secondary phases to improve strength, hardness, and wear resistance via second-phase strengthening and load-transfer mechanisms. However, in Al/steel tribopairs, such strategies focused solely on hardening the Al matrix composites often exacerbate abrasive wear on the steel counterpart, accelerating surface degradation and leading to premature system failure. To overcome this limitation, we propose a novel sepiolite-mediated reinforcement strategy: natural sepiolite (Spl) was incorporated into agglomerated Al powder and consolidated via spark plasma sintering to fabricate Spl/Al composites. The design exploits a tribo-triggered self-healing mechanism involving wear-induced dehydroxylation and exfoliation of sepiolite, release of reactive oxygen species, bidirectional transfer of metallic wear debris, and coupled tribochemical–mechanical reactions. Orthogonal SRV reciprocating sliding tests show that, compared with the pure Al/steel tribopair, the composite reduces wear volume by 7.59–47.68% and decreases the steel counterpart’s wear scar diameter by 1.25–34.3%, while the coefficient of friction is lowered by 4.85–58.88%. A self-healing tribolayer forms in situ on the contact surfaces, comprising hard phases (Al2O3, SiO2, SiC, MgSiO3, Fe3C, AlFe3) and lubricious components (graphite and unreacted sepiolite), which together confer an optimal balance of mechanical robustness and solid lubricity. This transforms the wear mode from direct Al/steel contact to sliding between conformal self-healing tribolayer, thereby significantly enhancing the overall tribological performance and durability of the tribopair.

The passive films formed on distinct regions (heat-affected zone (HAZ), base metal (BM), and weld metal (WM)) of Ti-6Al-4V alloy welded joints were comparatively investigated under hydrostatic pressures of 0.1 and 15 MPa in a simulated deep-sea environment. Results demonstrate that elevated hydrostatic pressure significantly degrades the corrosion resistance of passive films, with region-dependent susceptibility following the order: HAZ > BM > WM. This phenomenon is attributed to the synergistic interaction between hydrostatic pressure and residual stress. Among them, the residual tensile stress in HAZ enhances the effect of hydrostatic pressure, which greatly increases the density of defects in the passive film. Conversely, the compressive residual stress in WM exerts a protective effect, mitigating the detrimental influence of hydrostatic pressure on passive film integrity. The reduction of V content in beta phase in the WM region improves the stability of the passive film. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

This study successfully fabricated a gradient high-entropy alloy (GHEA) coating with structural and compositional dual heterogeneities, namely GHEA-Mo, on 38CrMoAl die steel via laser cladding. The microstructure evolution, mechanical properties, and tribological behavior under varying loads were systematically investigated. Results indicate that the coating exhibits a typical three-layer gradient structure: a dendritic dual-phase region dominated by the Laves phase at the top, a single-phase FCC structure at the bottom, and a nanoscale lamellar eutectic transition layer composed of FCC and Laves phases in the middle. This unique microstructure endows the coating with an excellent hardness gradient and a strength-ductility synergy. Tribological tests demonstrate that compared to the homogeneous Mo40Ni40Si20 coating, the GHEA coating exhibits lower friction coefficients and wear rates under loads ranging from 10 N to 100 N. The enhanced wear resistance is attributed to the toughening effect of the gradient structure, the formation of a stable oxide lubricating layer, and a transition in the dominant wear mechanism from abrasive wear to oxidative wear. This research provides new insights for designing high-performance wear-resistant coatings suitable for severe operating conditions.

A novel composite coating with sandwich structure was prepared on the anodic oxidation coating (AO coating) of Mg-Li alloy, which was mainly composed of layered double hydroxide (LDH) nanosheets and electroless NiP coating. The microstructure differences between MgAl-LDH nanosheets and high entropy MgAlNiCrZn-LDH nanosheets (HE-LDH) and their effects on the corrosion resistance of the coatings were investigated, especially the effects of the two types of LDH nanosheets on the galvanic corrosion between Mg-Li alloy and metal Ni. The results show that the sandwich composite coating can effectively improve the corrosion resistance of Mg-Li alloy, especially to inhibit galvanic corrosion. The improvement effect of high entropy LDH sandwich composite coating is significantly higher than that of the MgAl-LDH sandwich composite coating. The coupling current density between Mg-Li alloy and Ni alloy was reduced by approximately one order of magnitude, and the selfcorrosion current density of composite coating was reduced to 3.31 & times; 10-7 A & sdot;cm-2. HE-LDH nanosheets had better corrosion resistance, which may be due to the high charge density and densification of high-entropy LDH, which increased the adsorption and physical barrier to Cl-.

With increasingly stringent requirements for Zr alloys in terms of wear, corrosion, and tribocorrosion under extreme environments, the development of high-performance coating materials emerges as an effective approach to expand their application prospects. In this work, the laser-cladded AlNbTiV0.1W0.5Zr0.3-Cr/Cu high-entropy alloy (HEA) coatings were deposited on Zr alloys to facilitate their safe operation in harsh environments. The addition of Cr and Cu elements led to the formation of Cr2Nb Laves and CuZr phases, which considerably influenced the tribocorrosion behavior of the coating. The high-density stacking faults in the Cr2Nb-Laves phase served to significantly enhance the micro-hardness. The Cr2Nb Laves phase promoted the formation of a bipolar passive film in a lithium borate solution, thereby enhancing the corrosion resistance of the coating. The Cu-containing coating exhibited superior load-bearing capacity and stronger corrosion-wear resistance compared to the Cr-containing coating owing to its soft-hard alternating phase structure. In the solution, the HEA coatings primarily exhibited adhesive wear, where the synergistic effect between corrosion and wear accelerated pit development. Finally, mechanical wear was identified as the predominant mechanism of material degradation in friction and wear processes, while the dense passive layer on the coating surface effectively mitigated damage from tribocorrosion.

To investigate the two-phase strengthening mechanisms of nickel-based metal-ceramic composite coatings and their friction behavior at different temperatures, this study focuses on the high-temperature wear behavior of NiCrMoAl-Al2O3 composite coatings. NiCrMoAl-Al2O3 composite coatings were prepared using plasma enhanced high-velocity arc spraying (PE-HAS), and their mechanical properties were tested. Finally, friction and wear tests were conducted in air at 25℃, 300℃, and 500℃. The results indicate that the incorporation of Al2O3 significantly improves the mechanical properties of the coating. The coating’s microhardness was 655 HV0.2, representing a 74.2% increase compared to the base alloy, with an average bond strength of 59.33MPa and good ductile-brittle behavior. The wear mechanism changes with temperature; the coating exhibited optimal wear resistance at 300℃, while wear resistance decreased significantly at 500℃. This is primarily due to the hard Al2O3 phase, which is uniformly dispersed throughout the composite coating, enhancing its hardness and wear resistance. At 300℃, a dense oxide protective film forms at the friction interface to mitigate wear, whereas at 500℃, the oxide film fractures, generating a large number of hard abrasive particles. This induces a synergistic failure mechanism involving abrasive, adhesive, and fatigue wear, thereby accelerating coating degradation. The research findings elucidate the friction behavior of metal-ceramic coatings under varying temperature conditions, providing a reliable reference for the process optimization and practical engineering applications of such coatings.