Structural Evolution Mechanism Research Articles

Valuing the spatial structure and influencing factors of urban innovation from the perspective of social networks

ABSTRACT Valuing the spatial structural characteristics and evolution mechanisms of urban innovation networks (UIN) is crucial for promoting regional innovation development. This study constructs the UIN for the Yangtze River Economic Belt (YREB) and examines its spatial structural characteristics and driving factors from a social network perspective. The results indicate that: First, the network relationships within the urban innovation ecosystem in YREB continue to expand, enhancing stability, synergy and connectivity. Second, interaction relationships dominate the network, establishing distinct block functions, with provincial capitals serving as core nodes. Third, YREB can be divided into four blocks: the main inflow block, the main outflow block, the bidirectional spider block and the agent block, each exhibiting unique roles within the network. Fourth, increasing network density and connectedness while reducing hierarchy and enhancing efficiency positively impacts urban innovation. Strengthening node centrality characteristics is beneficial for promoting urban innovation. Lastly, proximity is conducive to the formation of UIN. Digital technology and traffic integration are replacing geographical and institutional factors, becoming key elements in the formation of UIN. Therefore, we propose optimising the spatial structure of UIN and shifting the driving paradigm from geographic and institution proximity to the digital technology and traffic proximity.

Mn vacancy engineering design of Fe/Mn based cathodes for breaking the spell between “sodium limiting” in air-stabilization and “sodium promoting” on kinetics

Fe/Mn-based cathode is considered a viable choice for sodium-ion batteries (SIBs) because of its affordability and high theoretical capacity. Nonetheless, bad actually comprehensive performance still impede its commercial application. In this work, based on the systematic study of P2-Na2/3Fe1/2Mn1/2O2 cathode materials with fewer Mn vacancies (NFM-Q), we realized a superior rate, cycling performance, air stability and more importantly unraveled the operation mechanism. Specifically, dual function of fewer Mn vacancies were explicitly clarified, which included the effect of shrinking sodium layers and the sodium-ion diffusion promoting effect, as confirmed by combining XRD, XANES, XAFS, EIS and GITT. So Mn vacancy engineering had the potential to break the contradiction between “sodium limiting” based on air-stabilization mechanism and “sodium promoting” based on kinetics. This has rarely been found before. And a series of characterizations strongly declared rapidly cooling rate could effectively regulated the creation of Mn vacancies. As a result, NFM-Q cathode not only delivered outstanding discharge capacity (192.7 mAh/g), cycling stability (123.8 mAh/g, 65 %, after 50 cycles) and energy density (574.0 Wh Kg−1), but also possessed splendid air stability (185.8 mA h/g, 61.8 % after 50 cycles and immersion). Moreover, ex-situ XRD and XAS further expounded structural evolution and charge compensation mechanism of NFM-Q cathode, confirming its superior performance. This work might offer fresh understanding about the roles of Mn vacancy engineering, which could open up new possibilities on the material design and the property improvement of Fe/Mn-based cathodes.

Structural evolution and stabilisation mechanism of foam fluids that contain cellulose nanofibres and cellulose nanocrystals: An experimental and theoretical study

Foam fluids are thermodynamically metastable systems, and they evolve over timescales comparable to their time of use, which makes the study of their destabilisation mechanisms crucial for many industrial applications. In our study, foams were made from fluids that contained cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs). We explored the effects of nanocelluloses and oils (n-heptane and n-dodecane) on foam stability, bubble coarsening and liquid drainage. Results show that the evolution of the bubble size is strongly slowed by the synergistic effect of CNCs and CNFs, and the structural evolution of foam is greatly impacted. The main responsible mechanism is an increase in local yield stresses due to the presence of CNCs in the foam. The jammed CNCs in foam produce a drainage delay, which makes the foam 50 % drainage time (t50%) of the experimental value deviate by up to 400 % from the classical theory value. When the bubbles coarsen and grow above a threshold size, liquid can drain out of the foam. Finally, a modified model for t50% that considers the drainage delay was proposed. The experimental results validated the proposed correlation and exhibited good reliability and predictive accuracy. The results enable us to elucidate the impact of CNCs and CNFs on the stability of foam fluids.

A Cascade Reaction Triggered by H‐H Steric Hindrance: Dimeric Covalent Organic Frameworks on Au(111) and Dimeric Nanoribbons on Ag(111)

Comprehensive SummaryIn on‐surface synthesis, dimers are typically utilized to explore reaction mechanisms or as intermediates in the formation of final products. However, constructing the innovative nanostructures with dimers as building blocks remains challenging. Here, using non‐planar 2,2′,7,7′‐tetrabromo‐9,9′‐biflurenyliden molecules, we have successfully synthesized dimeric covalent organic frameworks (COFs) on the Au(111) surface through a temperature‐controlled cascade reaction. Notably, the H‐H steric hindrance within precursors caused by double bonds leads to selective stepwise debromination during the thermal annealing, which promotes the dimerization through intermolecular Ullmann coupling and cyclodehydrogenation reaction to form COFs primarily constituted by dimer building blocks. Combining scanning tunneling microscopy/spectroscopy and density functional theory calculations, we have precisely confirmed the structural evolution and reaction mechanism. Furthermore, by introducing Ag adatoms to form C−Ag−C intermediates, we have successfully regulated the reaction path and synthesized one‐dimensional nanoribbons with dimers as building blocks. This work not only validates the strategy of synthesizing dimeric nanostructures on different surfaces through cascade reactions induced by precursor design, but also enriches the research field of surface synthesis of COFs and nanoribbons.

Hydrothermal carbonization of woody waste: Changes in the physicochemical properties and the structural evolution mechanisms of hydrochar during this process

The Chinese medicine residue (CMR) is composed of wet woody waste, including licorice and ephedra, so using hydrothermal carbonization (HTC) to recover renewable energy from the CMR is a suitable treatment method. An in-depth analysis of the physicochemical properties and structural evolution mechanism of hydrochars is helpful in fundamentally promoting the energy utilization of traditional Chinese medicine waste residue. Therefore, this study analyzed the physicochemical properties and morphological structure of hydrochar produced under varying HTC conditions using multiple testing methods. The evolution of the hydrochar's structural characteristics can be categorized into three stages: component decomposition, structural rearrangement, and carbonization. During the component decomposition and carbonization stages, numerous nanoscale micropores form within the hydrochar. These micropores' specific surface area and pore volume can reach up to 113.420 m2/g and 0.01913 cm3/g, respectively. The highest fractal dimension values for D1 and D2 are 2.6354 and 2.5565, while the maximum values for the microcrystalline stacking height (Lc) and the average number of crystalline layers (Nave) are 0.3354 and 1.9968, respectively. Consequently, the hydrochar produced during these stages exhibits a rougher pore surface and a more complex structure, making it more suitable for adsorbing heavy metals from soil and sequestering CO2. During the structural rearrangement stage, the hydrochar exhibits higher contents of fixed carbon (FC), MgO, P2O5, and a higher C/N atomic ratio, with maximum values of 38.51%, 0.99%, 1.12%, and 28.49, respectively. Thus, the hydrochar produced during this stage is more suitable for soil remediation and nutrient recovery.

Structural evolution and catalytic mechanisms of perovskite oxides in electrocatalysis.

Electrocatalysis plays a pivotal role in driving the progress of modern technologies and industrial processes such as energy conversion and emission reduction. Perovskite oxides, an important family of electrocatalysts, have garnered substantial attention in diverse catalytic reactions because of their highly tunable composition and structure, as well as their considerable activity and stability. This review delves into the mechanisms of electrocatalytic reactions that use perovskite oxides as electrocatalysts, while also providing a comprehensive summary of the potential key factors that influence catalytic activity across various reactions. Furthermore, this review offers an overview of advanced characterizations used for studying catalytic mechanisms and proposes approaches to designing highly efficient perovskite oxide electrocatalysts.

Structure-activity relationship and deactivation behavior of iron oxide during CO2 hydrogenation

Identifying the dynamic structural evolution of iron during the thermocatalytic conversion of CO2 into liquid hydrocarbons is a promising approach for understanding the deactivation behavior and to design an efficient catalyst. Despite the understanding of the oxidation of χ-Fe5C2 to high-valent iron oxides (e.g., Fe3O4, Fe2O3) caused by water formed as the byproduct, the deactivation mechanism depending on the particle size during a long-term reaction remains unclear. Herein, the structural evolution and deactivation mechanism of Na-promoted Fe2O3 catalysts with varying particle sizes were investigated. The catalyst activity and deactivation behavior were highly dependent on the initial morphology of the calcined catalysts. The reduced iron catalyst with an average particle size (dave) of 0.52 μm maintained its domain integrity, whereas that with a dave value of 2.18 μm was severely pulverized during the CO2 hydrogenation. The pulverized particles exposed a new surface, making it highly susceptible to re-oxidation and catalyst deactivation. Conversely, maintenance of the iron integrity suppressed the re-oxidation, whereas the excess formation of graphitic carbon on the χ-Fe5C2 site was the main deactivation mechanism during long-term CO2 hydrogenation.

Laser Irradiation Induced Electronic Structure Modulation of the Palladium-Based Nanosheets for Efficient Electrocatalysts.

Palladium nanosheets (Pd NSs) are widely used as electrocatalysts due to their high atomic utilization efficiency, and long-term stability. Here, the electronic structure modulation of the Pd NSs is realized by a femtosecond laser irradiation strategy. Experimental results indicate that laser irradiation induces the variation in the atomic structures and the macrostrain effects in the Pd NSs. The electronic structure of Pd NSs is modulated by laser irradiation through the balancing between Au-Pd charge transfer and the macros-strain effects. Finite element analysis (FEA) indicates that the lattice of the nanostructures undergoes fast heating and cooling during laser irradiation. The structural evolution mechanism is disclosed by a combined FEA and molecule dynamics (MD) simulation. These results coincide well with the experimental results. The L-AuPd NSs exhibit excellent mass activity and specific activity of 7.44 A mg-1 Pd and 18.70mA cm-2 toward ethanol oxidation reaction (EOR), 4.3 and 4.4 times higher than the commercial Pd/C. The 2500-cycle accelerated durability (ADT) test confirms the outstanding catalytic stability of the L-AuPd NSs. Density functional theory (DFT) calculations reveal the catalytic mechanism. This unique strategy provides a new pathway to design the ultrathin nanosheet-based materials with excellent performance.

Crystal structure evolution and solid solution mechanism of Al2O3-Cr2O3 system under different reaction conditions

The (Al1-xCrx)2O3 solid solution (ACS) is expected to be an low pollution chromium source for high-performance alumina-chromium oxide refractory materials. In this work, the effects of Cr2O3 content and reaction conditions on the solid solution behavior in the Al2O3-Cr2O3 system were explored and the mechanism was revealed. The relationship between the lattice parameters of the formed ACS phase and the content of Cr2O3 was closer to a linear one as the temperature rose, serving as an indicator for a higher degree of reaction. The solid solution reaction between Al2O3 and Cr2O3 was governed by the diffusion processes of Al3+ and Cr3+ at 1300–1500 °C and 1200 °C, respectively, and thus the increase of Cr2O3 content slowed the solid solution reaction at a low temperature whereas promoted it at elevated temperatures. The diffusion process of solid solution reaction within the Al2O3-Cr2O3 system was consistent with the Cater model; The diffusion activation energy (Ea) decreased as the content of Cr2O3 increased at 1300–1500 °C. When the content of Cr2O3 increased from 25 to 60 mol%, the diffusion activation energy decreased from 92.48 to 86.49 kJ/mol−1, which was attributed to the augmentation in the diffusion rate of Cr3+ caused by the increase of Cr2O3 content and its vapor-phase transport mechanism at high temperatures.

Dissolution zone model of the oxide structure in additively manufactured dispersion-strengthened alloys

The structural evolution of oxides in dispersion-strengthened superalloys during laser-powder bed fusion is considered in detail. Alloy chemistry and process parameter effects on oxide structure are assessed through a parameter study on the model alloy Ni-20Cr, doped with varying concentrations of Y2O3 and Al. Small angle neutron scattering measurements of the complete dispersoid size distribution show the dispersoid size increases with higher laser power, slower scan speed, and increasing Al and Y2O3 content. Complementary electron microscopy measurements reveal reactions between Y2O3 and Al, even in nanoscale dispersoids, and the presence of micron-scale oxide slag inclusions in select specimens. A scaling analysis of mass and momentum transport within the melt pool, presented here, establishes that diffusional structural evolution mechanisms dominate for nanoscale dispersoids, while fluid forces and advection become significant for larger slag inclusions. These findings are developed into a theory of dispersoid structural evolution, integrating quantitative models of diffusional processes – dispersoid dissolution, nucleation, growth, coarsening – with a reduced order model of time-temperature trajectories of fluid parcels within the melt pool. Calculations of the dispersoid size in single-pass melting reveal a zone in the center of the melt track in which the oxide feedstock fully dissolves. Within this zone the final Y2O3 size is independent of feedstock size and determined by nucleation and growth kinetics. If the dissolution zones of adjacent melt tracks overlap sufficiently with each other to dissolve large oxides, formed during printing or present in the powder feedstock, then the dispersoid structure throughout the build volume is homogeneous and matches that from a single pass within the dissolution zone. Gaps between adjacent dissolution zones result in oxide accumulation into larger slag inclusions. Predictions of final dispersoid size and slag formation using this dissolution zone model match the present experimental data and explain process-structure linkages speculated in the open literature.

Study on combustion characteristics of crustacean biomass derived fuel coupled with in-situ capture of SO2 based on pulsed microwave radiation

Crustacean waste has great potential as fossil fuel substitution and efficient desulfurization to reduce pollutant emissions, but high moisture and poor quality restrict broad-scale utilization. This study used microwave radiation on crayfish shell to investigate the combustion characteristics and desulfurization effect in different atmospheres/pulse microwave cycle. Meanwhile, the structure evolution mechanism and molecular reaction pathways were revealed. The results show that crayfish shell derived fuel has a pleasurable combustion performance and sulfur fixation ability after microwave radiation in flue gas. The heat release of derived fuel increased by 29.9 % after five microwave cycle in flue gas, and activation energy decreased by 3.7 %. By contrast, the heat release increased by 17.4 % after five microwave cycle in inert gas, and activation energy increased by 39.3 %. Subsequently, the effect of microwave cycle times in flue gas on crayfish shell combustion and desulfurization performance was studied. The results show that the heat release of derived fuel gradually increases with microwave cycle. After seven microwave cycle, the derived fuel heat release and SO2 removal efficiency increased by 34.9 % and 44.4 %, respectively. The results establish the foundation for expanding the utilization pathway of crustacean waste and realizing the low-carbon energy transition.

Computational insights from the thermal spike model into mesoporous silica behavior during swift heavy ion irradiation

Mesoporous silica materials are pivotal in various scientific domains due to their unique properties and versatile applications. However, understanding their response to irradiation, particularly from Swift Heavy Ions (SHI), remains limited. We address this gap by investigating experimental mesoporous silica behavior under 12 MeV Carbon and 92 MeV Xenon bombardment using the Three-Dimensional Thermal Spike Model (3DTS) simulation. Our computational simulations reveal localized heating effects and provide mechanistic insights into experimental observations, shedding light on pore closure and different observed damage patterns. This study is the first application of this model to porous silica and deepens our knowledge of the mechanism of structural evolution under ion bombardment.

Pressure-Induced Changes in the Phase Distribution and Carrier Dynamics of Quasi-Two-Dimensional Ruddlesden-Popper Perovskites.

Quasi-two-dimensional (quasi-2D) perovskites hold significant potential for diverse design strategies due to their tunable structures, exceptional optical properties, and environmental stability. Due to the complexity of the structure and carrier dynamics, characterization methods such as photoluminescence and absorption spectroscopy can observe but cannot precisely distinguish or identify the phase distribution within quasi-2D perovskite films or correlate phases with carrier dynamics. In this study, we used pressure to modulate the intralayer and interlayer structures of (PEA)2Csn-1PbnBr3n+1 quasi-2D perovskite films, investigating charge carrier dynamics. Steady-state spectroscopy revealed phase transitions at 1.62, 3, and 8 GPa, with free excitons transforming into self-trapped excitons after 8 GPa. Transient absorption spectroscopy elucidated the structural evolution, energy transfer, and pressure-induced transition mechanisms. The results demonstrate that combining pressure and spectroscopy enables the precise identification of phase distribution and pressure response ranges and reveals photophysical mechanisms, providing new insights for optimizing optoelectronic materials.

All‐in‐One: Plasmonic Janus Heterostructures for Efficient Cooperative Photoredox Catalysis

AbstractJanus heterostructures consisting of multiple jointed components with distinct properties have gained growing interest in the photoredox catalytic field. Herein, we have developed a facile low‐temperature method to gain anisotropic one‐dimensional Au‐tipped CdS (Au−CdS) nanorods (NRs), followed by assembling Ru molecular co‐catalyst (RuN5) onto the surface of the NRs. The CdS NRs decorated with plasmonic Au nanoparticles and RuN5 complex harness the virtues of metal‐semiconductor and inorganic‐organic interface, giving directional charge transfer channels, spatially separated reaction sites, and enhanced local electric field distribution. As a result, the Au−CdS−RuN5 can act as an efficient dual‐function photocatalyst for simultaneous H2 evolution and valorization of biomass‐derived alcohols. Benefiting from the interfacial charge decoupling and selective chemical bond activation, the optimal all‐in‐one Au−CdS−RuN5 heterostructure shows greatly enhanced photoactivity and selectivity as compared to bare CdS NRs, along with a remarkable apparent quantum yield of 40.2 % at 400 nm. The structural evolution and working mechanism of the heterostructures are systematically analyzed based on experimental and computational results.

All-in-One: Plasmonic Janus Heterostructures for Efficient Cooperative Photoredox Catalysis.

Janus heterostructures consisting of multiple jointed components with distinct properties have gained growing interest in the photoredox catalytic field. Herein, we have developed a facile low-temperature method to gain anisotropic one-dimensional Au-tipped CdS (Au-CdS) nanorods (NRs), followed by assembling Ru molecular co-catalyst (RuN5) onto the surface of the NRs. The CdS NRs decorated with plasmonic Au nanoparticles and RuN5 complex harness the virtues of metal-semiconductor and inorganic-organic interface, giving directional charge transfer channels, spatially separated reaction sites, and enhanced local electric field distribution. As a result, the Au-CdS-RuN5 can act as an efficient dual-function photocatalyst for simultaneous H2 evolution and valorization of biomass-derived alcohols. Benefiting from the interfacial charge decoupling and selective chemical bond activation, the optimal all-in-one Au-CdS-RuN5 heterostructure shows greatly enhanced photoactivity and selectivity as compared to bare CdS NRs, along with a remarkable apparent quantum yield of 40.2 % at 400 nm. The structural evolution and working mechanism of the heterostructures are systematically analyzed based on experimental and computational results.

Phase structure evolution and coercivity mechanism of high-Co containing permanent magnets

Abstract The phase structure and magnetic properties of high-Co containing permanent magnets with high thermal stability have been systematically studied in this work. It is abnormal that the coercivity of annealed samples was slightly lower than that of sintered samples, while the coercivity was usually enhanced after annealing in conventional Nd–Fe–B samples. Further analysis showed that in addition to RE2(Fe,Co)14B main phase and RE-rich grain boundary phase, there were also new Co-rich magnetic phases located in the grain boundary. During annealing, the phase structures of high-Co containing magnets were readjusted, especially the increasing Co-rich magnetic phase and emerging RE-rich particles precipitated from the main phase. Eventually, the isolated RE-rich particles would act as the pinning center of the domain wall movement in demagnetization process. It was confirmed that the coercivity of annealed high-Co containing magnets was controlled by both nucleation and pinning. Pinning mechanism can partially compensate for the weakening of magnetic isolation due to increased Co-rich magnetic phase, which explained the moderate decrease in coercivity of annealed high-Co containing magnets. The discovery of new coercivity mechanism contributed to in-depth understanding of high-Co containing magnets.

Structural evolution mechanism and magnetic properties of soft magnetic composites transformed from FeSiAl/Co3O4 composites

Simultaneous optimization of core loss and saturation magnetization in soft magnetic composites (SMCs) is crucial for the development of high frequency and high power in power electronic devices. In this work, FeSiAl/(Al2O3-Co) and FeSiAlCo/Al2O3 SMCs were prepared by sintering FeSiAl/Co3O4 composite powders at different temperatures. The corresponding structural evolution mechanism and magnetic properties of the prepared SMCs were studied systematically. When the sintering temperature was below 950 ℃, a chemical reaction at the FeSiAl/Co3O4 interface occurred and led to the formation of Al2O3-Co composite coating. The Al2O3 coating, as an isolation band, can effectively hinder the interdiffusion between Co coating and FeSiAl magnetic powder. When the sintering temperature increased to above 1000 ℃, the interdiffusion began to occur and was accelerated by the high temperature and chemical potential educed by concentration gradient, finally resulting in the formation of FeSiAlCo alloy. The prepares SMCs exhibited a low core loss due to the high integrity of Al2O3 coating. Its saturation magnetization and permeability significantly increased with the sintering temperature due to the generation of Co coating with ferromagnetism. This work provides a new strategy for the construction of ceramic oxide coating with high integrity and elemental doping of magnetic powder in SMCs, which is expected to be applied to the preparation of high-performance SMCs.

The Influence of Grain Size Gradation on Deformation and the Void Structure Evolution Mechanism of Broken Rock Mass in the Goaf

The high porosity and high specific surface area of the broken rock mass in abandoned mine goaf make it an excellent thermal storage space. The void structure is an important factor that affects the permeability characteristics of broken rock mass, which determines the efficiency of extracting geothermal water from abandoned mine shafts. To accurately describe the void structure of broken rock mass, the effect of particle erosion on the fracture of rock blocks is considered in this study, based on which an impact-induced strength corrosion calculation model was proposed. Then, this calculation model was embedded into the three-dimensional numerical simulation of broken rock mass for secondary development. A discrete element numerical calculation model was established for broken rock masses with different size grading distributions under water immersion and lateral compression conditions. On this basis, considering the strength erosion effect of impacts, this study investigated the deformation and fracture characteristics of broken rock masses with different size grading distributions and analyzed the evolution laws of porosity in the broken rock masses. The main findings are as follows: The impact effect has a significant influence on the growth of microcracks and the breakage rate of broken rock mass. When the particle size of the broken rock mass differs significantly (size grading as G3), impact-induced strength erosion exerts the greatest impact on the growth of microcracks and the breakage rate. When the particle size of the broken rock mass is uniform (size grading as G1), impact-induced strength erosion minimally impacts the secondary fracturing of the broken rock mass. When the strain of the broken rock sample is less than 0.175, the distribution of microcracks is scattered; when the strain reaches 0.275, microcrack propagation accelerates and exhibits a clustered distribution; and when the strain reaches 0.375, microcracks exhibit a reticular distribution and their connectivity is enhanced. With the increase in deformation, the broken rock mass porosity decreases, and the porosity curve fluctuates along the z-axis with a decreasing trend and gradually becomes more uniform. This study provides a theoretical foundation for assessing the efficiency of extracting and storing mine water with heat in abandoned mine geothermal mining projects.

Study on the mechanism of rapid densification and structural evolution of C/C composites by cooling pyrolysis

A large thermal gradient about 190 ℃/cm was established in the thickness direction of preform and the cylindrical carbon/carbon composites with radial gradient pyrocarbon (PyC) distribution were rapidly prepared via the cooling pyrolysis technology in the high temperature surface based on the large thermal gradient chemical vapor infiltration (CPTHTS-LTGCVI). The decrease of initial temperature and the increase of cooling rate both contribute to the opening of closed pore and pore expansion, which are conducive to improving the densification degree. Moderate initial temperature (about 1130℃) and cooling rate (10 ℃/5 h) are optimal to rapidly preparing C/C composites with good density uniformity. For the whole cylindrical C/C composites, the faster the cooling rate, the higher the density and density uniformity, the fewer the super macropores. As the cooling rate is 10 ℃/2.5 h, the density of sample can reach 1.57 g/cm3 within 50 h, and the carbon yield in the first stage and accumulation can reach 84 % and 50 %, respectively. From the inner wall (IW) to the outer wall (OW), there are three successive regions about RL, RL+SL and SL PyC with gradually weakened texture, which is related to the insufficient pyrolysis caused by the decreased temperature and increased concentration, and the aromatization caused by the extended gas retention time. The edge dislocations and non-coherent sub-grain boundaries of PyC may be related to the distorted aromatic carbon planes containing five-membered rings. The edge dislocations may be the main reason of texture reduction and structural evolution of PyC.

Study on pore structure evolution and water damage of asphalt mixture under cyclic loading

For a long time, the water damage issues of asphalt mixture pavements have been highly regarded by engineers. However, the existing research is difficult to accurately describe the fatigue damage process of asphalt mixture under hydrodynamic pressure environments. In order to reveal the influence of water damage on the asphalt mixture structure and its mechanism, this study combined low-field NMR technology to investigate the evolution law of asphalt mixture pore structure under cyclic loading with different parameters. The erosion effect of the coupled loading-dynamic water environment on asphalt mixtures and their failure mechanisms are analyzed. The results show that the initial damage dominated by harmful pores and major-harm pores provides space for water migration and storage, and improves the sensitivity of asphalt mixture to water damage. Under the action of repeated cycles of stress increase-decrease, the irreversible hydrodynamic extrusion-cracking and friction-stripping deformations in the asphalt matrix increase. The micro-cracks inside the materials continue to expand and the pores are interconnected. To comprehensively consider the influence of initial porosity, maximum cyclic stress and the number of cycles, the cumulative damage model of the material is optimized based on the mechanism of pore structure evolution, and obtained more accurate porosity prediction results. This study can provide scientific reference and guidance for solving the problem of asphalt pavement disease and durability design.