Introducing nanoparticles (NPs) typically enhances the strength of composite, but compromises ductility. This study breaks this trade-off in TiB2 nanoparticle-reinforced Al-Zn-Mg-Cu composites, achieving a simultaneous increase in both properties. Through systematic investigation of microstructural evolution and strain-hardening behavior, we reveal that how NP addition dictates the dislocation dynamics and ductility. Crucially, composite ductility exhibits a non-monotonic trend, with a peak at 3 wt% where the composite surpasses the unreinforced alloy in both strength and ductility. We rationalize this synergy by developing a physics-based model that incorporates NP-dependent dislocation recovery kinetics. This model quantitatively explains and accurately analyzes the ductility trends: at low NP contents (1-3 wt%), NPs retard dislocation recovery, delaying necking, while at high NP content (5 wt%), recovery is accelerated. Microstructural analysis indicates that low NP addition suppresses localized slip band formation, promoting uniform dislocation distribution and stabilizing plastic flow. This work provides a fundamental understanding of dislocation-NP interactions and offers an assessment tool for designing high-performance metal matrix composite alloys by NP-induced dislocation dynamics.

The mechanical properties of aluminum alloys can be effectively enhanced by nano-and submicron-scale particles in-situ synthesized in aluminum melt. However, the presence of particles significantly influences the damage behavior of notched components. In this study, the fracture mechanisms of in-situ TiB2/Al-Zn-Mg-Cu composites with different notches are systematically investigated. The results indicate that the load-bearing capacity of the material is reduced with the decrease of notch radius. The reduction in notch radius leads to increasing stress triaxiality at the notch root, accompanied by a highly confined plastic zone, thereby suppressing macroscopic plastic deformation and promoting early damage initiation. In-situ tensile testing demonstrates that the particle aggregates increase the number of damage initiation sites due to intensified mechanical constraint, facilitating microcrack formation through particle aggregate fracture or particle/matrix interfacial debonding. Fractographic observations near the notch root reveal a triangular zone, the size of which decreases with decreasing notch radius. It indicates that highly localized plastic deformation forms at the notch root prior to shear-dominated tearing in the surrounding regions. It is found that the premature failure of notched TiB2/Al-Zn-Mg-Cu composite originates from the synergistic effects of notch geometry-induced mechanical constraint and the increasingly dominant role of TiB2 particles and aggregates as damage initiation sites. These findings provide valuable insights for the engineering design and application of such composites in notched structural components.

The quench sensitivity of an in situ TiB2/7050 Al composite was investigated by correlating hardness degradation with quench-induced precipitation. The time–temperature-property curve exhibited a nose temperature of approximately 350 °C, with pronounced quench sensitivity between 325 and 385 °C. The fastest hardness loss occurred near 355 °C, where the hardness retention decreased to approximately 55

High-strength Al-Zn-Mg-Cu alloys and their composites are attractive for aerospace and other lightweight structural applications. Wire-laser directed energy deposition (WLDED) offers high deposition efficiency, high material utilization, and suitability for large and complex components. However, microstructural heterogeneity induced by WLDED poses a significant challenge in achieving a desirable balance between mechanical properties and corrosion resistance. In this work, a 4.0wt% TiB2/7055 composite was successfully fabricated by WLDED and subsequently subjected to peak aging (PA) and retrogression and re-aging (RRA) treatments. In the different states, the composites all exhibited fine and relatively uniform equiaxed grain structure. After the PA treatment, the yield strength and ultimate tensile strength increased to 570 ± 8MPa and 634 ± 9MPa, respectively. Notably, RRA treatment further increased them to 618 ± 7MPa and 675 ± 7MPa, respectively. RRA treatment also enhanced corrosion resistance, compared with the AD state; its corrosion current density and intergranular corrosion depth were reduced by approximately 68.6% and 77.0%, respectively. The strength enhancement of the RRA state was mainly attributed to the retention of dense intragranular η′ precipitates and RRA-regulated precipitation at the TiB2/Al interfaces, which narrowed the particle-associated precipitate-free zones. Meanwhile, RRA treatment transformed connected precipitate-associated corrosion pathways into more isolated corrosion sites by promoting the discontinuous distribution of grain-boundary precipitates and the dispersion of TiB2/Al interfacial precipitates. This study provides new insights into the synergistic optimization of strength and corrosion resistance in additively manufactured high-strength aluminum matrix composites.

High Mg content in Al-Mg-Zn-Cu aluminum crossover alloys (ACA) induces severe Portevin-Le Chatelier (PLC) effects and reduces elastic modulus. In this work, introducing nanoparticles into an Al-8.5Mg-3Zn-0.81Cu-0.11Zr ACA significantly enhances strength and modulus, yielding a high-Mg aluminum crossover composite (ACC). The nanoparticles cannot only arrest mobile dislocations directly, but also refine grains and accelerate T’ precipitation to reduce the diffusing Mg solutes, which enhance the dislocation pining effect. Finally, the PLC effect of high-Mg ACA is effectively suppressed by the modified microstructures. This study provides a viable strategy for designing high-strength and low-density aluminum alloys with stable plastic flow.

Spray-formed 3.5 wt% TiB2/7075 aluminum (Al) composites were successfully fabricated, exhibiting a homogeneous multiscale dispersion of in-situ synthesized TiB2 particles throughout an equiaxed and randomly oriented Al matrix. Hot compression tests were conducted across deformation temperatures of 350–450 °C and strain rates of 0.001–1 s−1 to systematically investigate the flow behavior, constitutive characteristics, processing capability, and microstructure evolution. The flow stress exhibited pronounced sensitivity to both temperature and strain rate, while constitutive analysis yielded an apparent activation energy of 160.46 kJ/mol, slightly higher than that of spray-formed 7050 Al. Processing maps constructed using the dynamic materials model identified the optimal hot working window at 430–450 °C and 0.001–0.1 s−1 where flow instability is avoided. Microstructural characterization demonstrated that continuous dynamic recrystallization is the dominant restoration mechanism, significantly promoted by TiB2 particles. The transition between dynamic recovery and dynamic recrystallization occurs at ln Z ≈ 23–24, notably higher than in unreinforced spray-formed Al alloys. These findings establish a comprehensive framework for thermomechanical processing of particle-reinforced Al matrix composites.

The corrosion behavior of Al-Zn-Mg-Cu alloys in intergranular corrosion (IGC) and exfoliation corrosion (EXCO) environments has been widely studied, but the associated corrosion-induced mechanical damage remains unclear. This study systematically investigates the relationship between dissolution, corrosion product formation, and corrosion-induced mechanical damage in IGC and EXCO solutions. Experimental observations and thermodynamic calculations show that the alloy maintains a passive state in the IGC solution, though the passivation film may rupture. Micro-galvanic corrosion at Fe-bearing phases and grain boundary precipitates leads to pitting along grain boundaries. The resulting flocculent corrosion products exhibit low hydration and limited volumetric expansion, causing only minor damage. In contrast, the EXCO solution is much more aggressive, with a corrosion rate two orders of magnitude higher than in the IGC solution. Initially, the EXCO solution etches the alloy along high-angle grain boundaries, causing significant dissolution during the first similar to 12 h. With longer immersion, the alloy becomes passive again, but the ruptured passivation film offers limited protection. Meanwhile, the formation of expansive corrosion products drives layered exfoliation, which markedly reduces both strength and ductility. In comparison, the intergranular dissolution primarily degrades ductility. This work deepens the understanding of corrosion behavior and corrosion-induced mechanical damage in Al-Zn-Mg-Cu alloys under different levels of aggressiveness, paving the way for improved corrosion resistance.

This study investigates the influence of ceramic particles on controlling recrystallization and enhancing thermal stability in the pre-deformed aluminum matrix composite. Using an Al-Mg alloy reinforced with TiB2 particles as a model system, we demonstrated that ceramic particles act as potent nucleation sites for recrystallization while pinning grain boundaries to effectively inhibit the growth of recrystallized grains. This synergistic effect results in a significantly refined and thermally stable microstructure in the composite compared to the unreinforced alloy. We proposed a quantitative method to estimate the pinning force of TiB2 particles and thermal activation energy (Q) for grain growth from microstructure characterization. Our analysis reveals that the pinning force is not static but is influenced by the heat treatment schedule, and the grains recrystallized during low-temperature annealing exhibit a higher Q value for subsequent growth at elevated temperatures. This enhanced stability is attributed to the large grain boundary curvature resulting from particle-stimulated nucleation (PSN) at low temperature, which is then effectively stabilized by the TiB2 particles. These findings provide quantitative insights into the synergistic effects of PSN and Zener pinning, offering guidelines for designing particle-reinforced metal matrix composites with exceptional microstructural stability for demanding high-temperature applications.

This study systematically investigates the effects of dual Mg and Si additions on microstructural evolution and mechanical properties of a cast Al-Li-Cu alloy. The Mg and Si contents and their ratio (Mg/Si) strongly influence phase formation during solidification, dissolution behavior during solution treatment, and precipitation evolution during aging. Increasing the Mg/Si ratio promotes the formation of Mg2Si and suppresses AlLiSi formation, particularly at a Mg/Si ratio of 3. However, excessive Mg additions (>2.4 wt%) lead to severe grain-boundary segregation and promote the formation of low-melting-point phases, such as Al2CuMg and complex Al-Li-Cu-Mg phases, thereby reducing the incipient melting temperature and hindering complete dissolution during solution treatment. Alloys with moderate Mg and Si contents (e.g., 5M2S and 12M4S alloys) exhibit more effective dissolution of Cu-rich phases, while those with excessive additions retain coarse undissolved particles that deteriorate fracture toughness. During aging, Mg and Si additions inhibit theta' precipitation, promote a more uniform distribution of T-1 and nanoscale Mg2Si precipitates, and suppress the coarsening of delta '-Al3Li. Consequently, pronounced solid-solution and precipitation strengthening are achieved. Among the investigated alloys, the 5M2S alloy exhibits an optimal balance of strength and ductility after aging at 175 degrees C for 8 h, achieving a yield strength of 291 MPa, an ultimate tensile strength of 381 MPa, and an elongation of 3.1%. These findings elucidate the synergistic roles of Mg and Si in tailoring microstructural evolution and provide practical guidance for designing high-performance cast Al-Li-Cu alloys.

The precipitation behavior and microstructural evolution of cast Al-Li-Cu-Mg-Si alloys with varying Cu contents were systematically investigated. Cu addition alters the solidification pathway by promoting Cu-containing intermetallics (e.g., Al2CuMg and Al6CuLi3), suppressing Al2MgLi, and, at higher levels, destabilizing Mg2Si while inducing AlLiSi formation. During solution treatment, near-complete dissolution of Cu-rich primary phases occurs at Cu <= 2 wt%, whereas excessive Cu leads to persistent undissolved phases and reduced solute supersaturation. Aging behavior is predominantly governed by coherent delta '-Al3Li precipitates across all compositions, with nucleation and coarsening following diffusion-controlled ripening and showing limited sensitivity to Cu content. Only at prolonged aging times and Cu >= 1.5 wt% are minor amounts of plate-like T1-Al2CuLi and/or theta '-Al2Cu observed, with low volume fractions due to kinetic constraints inherent to cast microstructures. Mg2Si precipitates exhibit a Cu-dependent morphological transition during long-term aging. These results reveal a simplified, delta '-dominated precipitation pathway in cast Al-Li-Cu alloys, distinct from wrought counterparts, and provide insights for precipitation control in high-Li cast Al-Li-Cu systems.

A yield strength model is developed for the TiB2 nanoparticle (NP) reinforced precipitate-hardened aluminum (Al) matrix (TiB2/Al–Zn–Mg–Cu) composites based on microstructure characterization. According to the performance of alloy and counterpart composites with different particle additions (1, 3, 5 wt pct) and established model, the strength increments caused by reinforced particles and precipitates were quantified. The calculated results indicate that NPs addition may deteriorate to the strengthening contribution by precipitates. In particular, the negative influence of NPs on the strength increment caused by matrix precipitates should be attributed to the formation of interface precipitates at NP/Al interface and coarse MPs near dislocations pinned by NPs. The present work paves a way to understand the strengthening mechanisms in multi-phase strengthened alloys/composites.

The inherent limitations of traditional von Neumann architectures hinder the rapid development of internet of things technologies. Beyond conventional, complementary metal‐oxide‐semiconductor technologies, imaging sensors integrated with near‐ or in‐sensor computing architectures emerge as a promising solution. In this study, the multi‐scale van der Waals (vdWs) interactions in 1D tellurium (Te) atomic chains are explored, leading to the deposition of a photothermoelectric (PTE) Te nanomesh on a polymeric polyimide substrate. The self‐welding process enables the lateral vapor growth of a well‐connected Te nanomesh with robust electrical and mechanical properties, including a PTE responsivity of ≈120 V W −1 in the infrared light regime. Leveraging the PTE operation, the thermal‐coupled bi‐directional photoresponse is investigated to demonstrate a proof‐of‐principle in‐sensor convolutional network for edge computing. This work presents a scalable approach for assembling functional vdWs Te nanomesh and highlights its potential applications in PTE image sensing and convolutional processing.

Maximizing metal-substrate interactions by self-reconstruction of coadjutant metastable phases can be a delicate strategy to obtain robust and efficient high-density single-atom catalysts. Here, we prepare high-density iridium atoms embedded ultrathin CoCeOOH nanosheets (CoCe-O-IrSA) by the electrochemistry-initiated synchronous evolution between metastable iridium intermediates and symmetry-breaking CoCe(OH)2 substrates. The CoCe-O-IrSA delivers an overpotential of 187 mV at 100 mA cm−2 and a steady lifespan of 1000 h at 500 mA cm−2 for oxygen evolution reaction. Furthermore, the CoCe-O-IrSA is applied as a robust anode in an anion-exchange-membrane water electrolysis cell for seawater splitting at 500 mA cm−2 for 150 h. Operando experimental and theoretical calculation results demonstrate that the reconstructed thermodynamically stable iridium single atoms act as highly active sites by regulating charge redistribution with strongly p-d-f orbital couplings, enabling electron transfer facilitated, the adsorption energies of intermediates optimized, and the surface reactivity of Co/Ce sites activated, leading to high oxygen evolution performance. These results open up an approach for engineering metastable phases to realize stable single-atom systems under ambient conditions toward efficient energy-conversion applications. Maximizing metal-substrate interactions through self-reconstruction is a key strategy for efficient oxygen evolution catalysts. Here, the authors report high-density iridium atoms embedded in ultrathin oxyhydroxide nanosheets, showing high performance in the oxygen evolution reaction.

This study investigates the hot deformation mechanisms of a spray-formed 7050 Al-Zn-Mg-Cu alloy, focusing on the influence of temperature and strain rate via comprehensive microstructure characterization. Microstructure analysis reveals that both the dynamic recovery (DRV) and dynamic recrystallization (DRX) are governed by the Zener-Hollomon parameter (Z). DRV-formed substructures exhibit distinct stability: grains with high grain orientation spread (GOS, 3-4 degrees) stabilize at low temperatures, while those with low GOS (1-2 degrees) stabilize at high temperatures. Elevated temperature promotes DRX, but the operative mechanism critically depends on strain rate. Continuous DRX (CDRX) dominates at low rates (0.001-0.01 s(-1)), whereas discontinuous DRX (DDRX) prevails at high rates (0.1-1 s(-1)). Optimizing strain rate is key: low rates (0.001 s(-1)) achieve near-complete DRX and grain growth (80 % recrystallized area), while high rates (1 s(-1)) limit recrystallization (<= 50 % area) despite enhanced nucleation, yielding finer grains (5-15 mu m) with residual substructures. Local strain analysis shows recrystallized grains maintain low kernel misorientation (KAM<0.8 degrees), but high strain rates increase substructure KAM by 41.3 %, indicating incomplete energy dissipation. This study provides new insights on the microstructure modification by deformation for developing high performance aluminum alloys.

Electrochemically converting nitrate (NO3 -) to value-added ammonia (NH3) is a complex process involving an eight-electron transfer and numerous intermediates, presenting a significant challenge for optimization. A multi-elemental synergy strategy to regulate the local electronic structure at the atomic level is proposed, creating a broad adsorption energy landscape in high-entropy alloy (HEA) catalysts. This approach enables optimal adsorption and desorption of various intermediates, effectively overcoming energy-scaling limitations for efficient NH3 electrosynthesis. The HEA catalyst achieved a high Faradaic efficiency of 94.5 ± 4.3% and a yield rate of 10.2 ± 0.5 mg h-1 mgcat -1. It also demonstrated remarkable stability over 250 h in an integrated three-chamber device, coupling electrocatalysis with an ammonia recovery unit for continuous NH3 collection. This work elucidates the catalytic mechanisms of multi-functional HEA systems and offers new perspectives for optimizing multi-step reactions by circumventing adsorption-energy scaling limitations.

This work experimentally and analytically investigated the incipient cavitation behavior in four liquids with different physical properties: ethanol, de-ionized water, glycerine, and aluminum melt under ultrasonic irradiation close to the cavitation threshold with a frequency of 20 kHz. To identify the cavitation structure development and bubble motion of different liquids, cavitation structure under condition close to the cavitation threshold was in-situ observed via high-speed photography for optically transparent liquids and synchrotron radiation X-ray radiography technology for aluminum melt. The dynamic process of the cavitation bubble was numerically simulated on the bubble wall motion. Bubble characteristics were analyzed by more accurate relevant dimensionless quantities comparison obtained from the translational maximum bubble velocity measured by Particle Image Velocimetry (PIV). Based on the simulation results through multi-technology combination methods and dynamic simulation, the incipient cavitation characteristics of various liquid bulks in experimental conditions were estimated and compared. The insights gained from this study are valuable for improving the design and optimization of industrial processes involving cavitation, such as ultrasonic degassing, ultrasonic-assisted metal casting, and material processing. Understanding these cavitation characteristics can lead to more efficient and controlled applications in these fields and help in identifying more suitable transparent media for simulating the cavitation behavior of metal melts.

The multiscale topological learning framework, based on persistent topological Laplacians, captures complex interactions and enhances energy prediction accuracy in multi-atom systems.

The spin-polarization strategy by manipulating magnetic electrocatalysts can promote the spin-sensitive oxygen evolution reaction (OER) while developing efficient spin-polarized materials toward ampere-level OER is still challenging. Herein, a hierarchical inter-doped (Ru-Ni)Ox nanosheet array in situ grown on nickel foam is designed, which exhibits a distinguished overpotential of 286 mV at 1 A cm-2 under 0.4 T magnetic field and a steady lifespan of 200 h at the ampere current density (i.e., 1 A cm-2), outperforming most reported state-of-art spin-selective OER catalysts in alkaline electrolytes Integrating intrinsic and interfacial spin-polarization on the inter-doped (Ru-Ni)Ox nanosheet array can significantly boost the catalytic activity for ampere-level OER under a magnetic field. Specifically, the spin-aligned Ru sites optimize the rate-determined O & horbar;O coupling step to reduce the thermodynamic barrier of OER. Meanwhile, the charge transfer kinetics is promoted due to the accelerating spin-selective electron transfer via spin pinning at the ferromagnetic-antiferromagnetic interface. The design of a hierarchical spin-polarized structure that integrates intrinsic and interfacial spin-polarization strategies provides an additional route to developing a spin-polarized OER catalyst capable of serving ampere current densities.

Metal nitride coatings have been considered as a promising approach to improve the performance of metal bipolar plates for proton exchange membrane fuel cells (PEMFCs). In this study, NbNx coatings with three different ratios of N2/Ar (1:2, 1:1 and 3:1) were prepared on TC4 alloy substrates using the double glow plasma alloying technology. The NbNx coatings are homogeneous and dense, and the phase of the coating transforms from hexagonal β-Nb2N to δ′-NbN phase as the nitrogen content increases. All coatings demonstrate high protective efficiency, with the coating (N2/Ar ratio of 3:1) displaying the lowest current density of 8.92×10−6 A/cm2 at a working voltage of 0.6 V. The EIS results also show that this coating has the best corrosion resistance. Notably, it also presents the lowest interfacial contact resistance of 7.29 mΩ·cm2 at 1.5 MPa and good hydrophobicity. More importantly, this study provides a new idea and method for corrosion-resistant coatings of metal bipolar plates for PEMFC applications.

Additive friction stir deposition (AFSD) provides an innovative solution for the additive manufacturing of Al-Zn-Mg-Cu alloys and composites with poor printability due to their high hot crack sensitivity. The present work successfully fabricates TiB2/7055 composite deposit as high as 50 mm by AFSD, and systematically investigates the evolution of microstructure and mechanical properties during AFSD and heat treatment. The as-deposited composite exhibits fine equiaxed grains and dispersed TiB2 particles, being different from the feedstock with elongated grains and non-uniformly dispersed particles. Both the size of the primary eta-Mg(Zn,Cu,Al)(2) precipitates and hardness in the as-deposited composite show a significant height gradient along building direction, while the bottom region shows the largest precipitates with the lowest hardness and the top region shows the smallest precipitates with the highest hardness. After heat treatment, these non-uniform features can be eliminated, and the eta-Mg(Zn,Cu,Al)(2) precipitates dissolve into matrix. The fine grains exhibit excellent stability during heat treatment due to the pinning effect of dispersed TiB2 particles. Numerous homogenous nano-sized precipitates (similar to 4.8 nm, GPII zone and eta' phase) form at grain interior, and the interface precipitates (eta-Mg(Zn1.5Cu0.5)) form at the interface between TiB2 particle and Al matrix. In addition, the heat-treated composite achieves uniform mechanical properties across different height positions, with a hardness of 219 HV, tensile strength of 644-650 MPa, and ductility of 13-14.6 %. The corresponding strengthening and toughening mechanisms are thoroughly discussed. These findings provide valuable insights for the fabrication of Al matrix composites with an excellent strength-ductility combination.