We investigate the structural and dynamical properties of binary aluminum-titanium liquid metallic alloys, as a function of temperature and composition. We make use of MD-simulations, using a transferable machine-learning potential developed by Song et al. [Nature Communications 15, 10208 (2024)], and compare our results to experimental data. Although this potential was initially trained on solid properties, we find good agreement between the experimental data and the simulation results for the liquid state. The excess volume and compositional changes of the structure are captured well by the machine-learned potential. The simulation allows to disentangle local packing from chemical-ordering effects; the latter are found to be weak in Al-Ti. Dynamical quantities like the viscosity and the diffusion coefficients are also discussed.

Developing materials that combine both softness and stiffness is crucial for meeting the demands of complex and versatile applications. The realization of multistability through elaborate units has been demonstrated, but the trade-off between performance and light weight across different states remains underdeveloped. In this work, we pioneer the application of the soft-stiff responsive strategy to lightweight cellular materials through architecturally nesting two materials with contrasting properties. The proposed cellular materials can be reconfigured and switched between soft and stiff states, as demonstrated experimentally, theoretically and numerically. The soft state represents high perturbation sensitivity and prominent vibration isolation properties. The stiff state exhibits a strong load-carrying capability due to multi-synergistic mechanisms, with a crushing modulus and strength 668.78 and 1037.55 times as high, respectively, as the soft state in the cases of soft materials embedded in metal materials. The manipulable mechanical properties can be tuned across a broad design space while maintaining robust switchability. These advantages of the proposed bistate cellular materials offer promising application prospects from adaptive protection to shock absorption and beyond.

Gradient materials exhibit exceptional mechanical properties arising from their distinctive microstructure, whereas multi-principal element alloys have attracted intensive attention as a new class of advanced metallic materials. However, existing investigations on compositionally gradient structures have been primarily focused on steels, whereas research on multi-principal element alloys has been largely confined to the element species, leaving a knowledge gap regarding materials that combine compositional gradient with multi-principal element characteristics. Therefore, this paper presents a study on CoCrNi multi-principal element alloy with Co composition gradient in response to this gap. The uniaxial tensile deformation behavior is investigated employing molecular dynamics simulations, elucidating the microstructural evolution and clarifying the underlying mechanisms of the compositional gradient effect. The simulation results reveal that Co element contributes to enhancing the hardening capacity and reducing the elastic modulus of the material. Through quantitative statistical analysis of microstructural evolution, this paper reveals that introducing gradient distribution of Co can suppress HCP phase transformation and reduce the amorphization energy barrier, thereby enhancing the intensity of grain boundaries-related activities. Furthermore, the Cr segregation at grain boundaries induced by the distorted lattice is identified. It is revealed that Co gradient can promote the migration of Ni and Co atoms toward grain boundaries and grain interiors, and it also facilitates the uniform distribution of Cr atoms.

In this paper, a geometrically exact dynamic shell model incorporating flexoelectricity is developed, along with its formulation based on the weak form quadrature element method. The model accounts for the coupling between the strain gradient and the electric field within the framework of flexoelectricity, including size effects along the thickness direction. The validity and feasibility of the proposed formulation are demonstrated through several numerical examples involving typical geometrically nonlinear dynamic shell problems. Furthermore, the influences of the size-dependent coefficient and the flexoelectric coefficient on the dynamic response of microshell structures are investigated. In contrast to existing flexoelectric shell models, the present model employs a geometrically exact shell theory, providing an innovative framework for analyzing the dynamic behavior of flexoelectric microshells undergoing large displacements and rotations. This study is a step forward to better understand the flexoelectric effects on microshells under large deflections and also provides a feasible method to predict its nonlinear dynamic behaviors.

A hybrid Trefftz finite element method (HT-FEM) is developed for the elastic analysis of multiphase materials containing multilayer coated inclusions. Within each polygonal element, the intra-element displacement field is represented by a truncated, piecewise T-complete function set, in which the displacement and traction continuity conditions between adjacent phases are incorporated. A smooth auxiliary displacement field is defined along the element edges to describe boundary variations. The single hybrid functional couples the intra-element and boundary fields through boundary-only integration, forming a concise and efficient numerical scheme that requires no integration along material interfaces. Numerical validations are carried out on multilayer-coated fibers, coated-hole and coated-fiber systems, and annular domains with double coatings. The proposed method achieves consistent results compared with the fine-mesh ABAQUS simulations while using far fewer elements. These results demonstrate the high accuracy, high stability, and superior computational efficiency of HT-FEM for analyzing complex multilayer composite structures.

Heterogeneous metamaterials constitute a new frontier in architected materials, combining multiphase compositions, hierarchical architectures, and coupled multi physics interactions to achieve unprecedented mechanical and functional performance. By harnessing synergistic interactions among diverse material phases, unit cell topologies, and physical mechanisms, these metamaterials enable programmable, adaptive, and multifunctional responses far beyond those of homogeneous systems. This review provides a systematic synthesis of six major design strategies, multiphase design, hybrid architectures, interpenetrating composites, multi material fusion, multifeature integration, and data driven approaches, emphasising their structure–mechanism–property relationships and nonlinear coupling effects. We critically analyse how structural heterogeneity governs deformation evolution, energy dissipation, and cross field functionality, and highlight their broad potential in impact protection, flexible electronics, acoustic control, adaptive actuation, and thermal management. Finally, we identify key challenges in correlating multiscale structures with emergent functions, improving manufacturing scalability, and developing unified modelling frameworks. By bridging fundamental design principles with engineering applications, this review outlines the roadmap towards intelligent heterogeneous metamaterials, offering fresh perspectives for next generation multifunctional systems.

Although hypertension may affect the local biomechanical properties of ascending thoracic aortic aneurysms (ATAAs) with a bicuspid aortic valve (BAV), a comparison of the regional elastic properties of BAV-ATAAs between patients with and without hypertension is not yet available due to lack of biomechanical data. In this study, we collected 25 fresh ATAA samples from 17 hypertensive and 8 age-matched non-hypertensive patients who underwent elective aortic surgery. Biomechanical tests were executed to investigate the regional failure stresses and biaxial mechanical properties of BAV-ATAAs with and without hypertension. A material model was fitted to the biaxial experimental data to obtain model parameters in different regions. Histological analysis was performed to investigate the underlying microstructure and determine the percentages of elastic and collagen fibers. The circumferential failure stresses in the anterior, lateral, and posterior regions were significantly lower for the hypertensive group than in the non-hypertensive group. Regarding equibiaxial stresses, the hypertensive BAV-ATAAs showed significantly higher longitudinal tissue stiffness in the anterior and lateral regions than the non-hypertensive BAV-ATAAs. Collagen fiber hyperplasia was observed in the anterior and lateral regions of both the hypertensive and non-hypertensive BAV-ATAAs. However, in these regions the laminar structure of the elastic fibers was disrupted in several places and apoptotic smooth muscle cells were observed in the group with hypertension compared to the group without hypertension. In addition, the circumferential failure stresses in the anterior and lateral regions were significantly increased in the hypertensive group and strongly correlated with the collagen content. These results suggest that the regional elastic properties of the hypertensive BAV-ATAAs are more deteriorated than those of the non-hypertensive samples. Due to the significant impact on circumferential tensile strength, the hypertensive BAV patients may be at a higher risk of ATAA rupture than non-hypertensive BAV patients.

Recently, the spin-momentum locking of elastic wave have been uncovered in beam structures. This work provides a theoretical and experimental study on flexural beam wave, as frequency goes from low to high values. First, both Timoshenko's and Euler's beam theories are used to reveal the polarization of general displacement, as well as the spin angular momentum of flexural wave. Then, the chiral spin source is built up, and the resonance of source cube is observed to reverse the polarization of source cube itself. After that, the same signal pair are put upon chiral source cube. The asymmetric transmission of flexural wave is experimentally observed, from low to high frequency, witnessing the reversal of asymmetric direction due to source resonance. These theoretical and numerical results confirm the spin-momentum locking for flexural wave, within broad frequency range, and evidence the influences of source cube resonance.

The crack propagation behavior of single-crystal materials exhibits pronounced orientation dependence due to inherent anisotropy of atomic lattice, yet its underlying physical mechanisms have not been fully elucidated. In this study, anisotropic fracture mechanics model combined with molecular dynamics simulations were employed to systematically investigate the crack propagation behavior in single-crystal copper with different lattice orientation angles (0°∼45°). The angular distribution function derived from anisotropic theory accurately predicts the initial cleavage direction. When the orientation angle α is less than 22.5°, the 100 plane is preferred, whereas when α exceeds 22.5°, the 110 plane becomes critical plane. As the orientation angle increases, the crack propagation mode transitions from brittle cleavage to ductile fracture, attributed to the orientation-dependent dislocation emission behavior. Microstructure evolution analyses reveal a competing mechanism between the cleavage where a dislocation-free zone (DFZ) facilitates fast crack propagation, and the blunting where the plastic zone formed by dislocations suppresses crack propagation through shielding effects. In addition, this study identifies the key role of geometric softening, which leads to crack healing in the 30° sample, while the extensive geometric softening triggers a texture evolution from 〈100〉 to 〈110〉 in the 45° sample, resulting in a brittle-to-ductile transition. The present work establishes a quantitative correlation among crystal orientation, dislocation activity, and fracture behavior, providing theoretical guidance for the toughness regulation in single-crystal materials.

Lattice metamaterials have been demonstrated to hold significant potential in the field of energy absorption. However, certain inherent limitations considerably restrict their application in energy absorption field. For instance, under large deformations, lattice metamaterials are prone to buckling of vertical struts and plates, leading to an abrupt stress drop. Moreover, existing research on lattice metamaterials predominantly focuses on performance optimization for a single protective objective, which constrains their applicability across diverse energy absorption scenarios. In this study, based on the conventional simple cubic (SC) plate lattice metamaterial, a modified simple cubic (MSC) plate metamaterial is designed. The newly proposed MSC plate metamaterial not only effectively mitigates the issue of abrupt stress drop but also achieves multiple stress plateaus, thereby enabling protection for multiple targets. Remarkably, the MSC plate lattice demonstrates substantially enhanced energy absorption and crushing efficiency over the traditional SC design, with increases of 37.1% in crush force efficiency (CFE) during the first stress plateau and 38.7% in specific energy absorption (SEA). Comparison of the mechanical properties with representative lattice metamaterials reported in the literature reveals that the MSC design achieves a SEA level on par with that of conventional metamaterials, despite its advantageous lower relative density. In summary, the systematic investigation of the MSC not only advances the lightweight potential of existing lattice metamaterials but also realizes the objective of multi-target energy absorption protection.

High-quality α-Si3N4 powders are important raw materials for advanced ceramic fabrication. However, conventional pyrolysis or nitridation processes generally suffer from high crystallization temperatures, irregular particle morphology, and whisker-like growth. In this work, near-spherical α-Si3N4 powders were prepared by NaF-assisted molten-salt pyrolysis using silicon diimide [Si(NH)2] as the precursor. The effects of pyrolysis temperature and Si(NH)2:NaF volume ratio on the phase composition, crystallization behavior, particle size distribution, and morphology of the products were systematically investigated. Compared with the NaCl molten-salt system, the NaF system was more favorable for promoting the crystallization of Si(NH)2-derived Si3N4 at lower temperatures. The relative crystallinity increased with increasing pyrolysis temperature and reached 97.75% at 1500 °C. However, when the temperature was increased to 1400–1500 °C, partial transformation from α-Si3N4 to β-Si3N4 occurred, accompanied by particle coalescence and hard agglomeration. Considering both phase composition and morphology, the powder prepared at 1300 °C with a Si(NH)2:NaF volume ratio of 5:1 exhibited an α-Si3N4 content of 84.77 wt% and a relatively regular near-spherical morphology. Further variation of the molten-salt ratio showed that the mean particle size decreased from 1003.72 to 583.52 nm with increasing NaF content, whereas excessive NaF caused the attachment of fine crystallites on particle surfaces and reduced morphological regularity. The liquid-phase mass-transfer environment provided by NaF may facilitate the dissolution–precipitation and crystal growth of amorphous Si3N4, thereby weakening anisotropic growth and promoting the formation of near-spherical α-Si3N4 powders.

This paper investigates the fracture behavior and toughening mechanisms of diagonally reinforced square lattices with heterogeneous strong-weak phase distributions using finite element numerical simulations. The results indicate that the macroscopic fracture toughness is not solely determined by the geometric length of the crack path but also depends fundamentally on the intrinsic energy-dissipation properties of the material on the crack path. Configurations with a continuous strong-phase distribution can induce widespread plastic deformation and crack tip blunting, thereby significantly increasing energy dissipation and ultimately leading to enhanced fracture toughness. Based on the relationship of "strut breakage-unit cell failure-crack propagation", a reasonable method for quantitatively evaluating the fracture behavior of lattice materials is established through identifying the continuous evolution of macroscopic cracks from the discontinuous microscopic strut breakage. This enables effective characterization of equivalent crack extension and provides a basis for the calculation of fracture toughness. Furthermore, this paper updates the design strategy of fracture-resistant lattice materials that shifting from traditional fracture path regulation to energy dissipation proliferation, laying a theoretical foundation for the development of high-performance, strong, and tough lightweight structures.

In this paper, we systematically investigate the size-dependent mechanical response and crack propagation behavior of face-centered cubic (FCC) CoCrNi medium-entropy alloys (MEAs) with pre-existing cracks via molecular dynamics (MD) simulations. The investigation focuses on the stress-strain response, yield strength evolution, and microstructural deformation mechanisms in specimens with different grain sizes. In contrast to the classical Hall-Petch and inverse Hall-Petch relations observed in crack-free counterparts, the pre-cracked samples exhibit an anomalous size dependence. Specifically, the yield stress decreases with grain refinement in the larger-grain regime, whereas it exhibits a slight recovery in the smaller-grain regime (inverse Hall-Petch range), accompanied by the restoration of plasticity governed by grain boundary (GB) activities. Based on fracture mechanics theorem, this anomaly is fundamentally attributed to the stress concentration near the crack-tip. Furthermore, a transition in the crack propagation mode from transgranular to mixed, and ultimately to intergranular, is observed as grain size decreases, attributed to the intragranular dislocation starvation and the formation of nanotwins. Also observed are the dislocation emission/absorption at GBs and the reversible transformation of nanolayered HCP phases (stacking faults), among other microstructural evolution phenomena. This work provides insights into the synergy between crack propagation and plastic deformation in CoCrNi MEAs across different grain sizes, unraveling the atomic-scale mechanisms behind their superior mechanical properties.

Modeling elastic fields in materials with inclusions is pivotal to understanding the mechanical behavior of composites, yet conventional finite element formulations often suffer from high computational cost when dealing with complex inclusion geometries or fine stress concentrations. To address this challenge, we develop a hybrid Trefftz finite element method (HT-FEM) based on a single-functional formulation. The method assumes two independent displacement fields, one within the element domain and the other along its boundary, and couples them through a modified functional with the matrix-inclusion continuity conditions inherently satisfied by the intra-element field. This strategy avoids the need for interface integration, while preserving displacement and stress continuity across matrix-inclusion boundaries. Numerical studies demonstrate that the proposed method captures inclusion-induced local stress concentrations with high fidelity even on coarse meshes, and significantly reduces degrees of freedom and computational time compared with conventional finite element method (FEM). Further analysis reveals an intrinsic balance between the number of Gauss integration points and the admissible number of T-complete functions, and shows that increasing the number of polygonal element edges can further increase the accuracy. Benchmark cases with randomly distributed inclusions or voids in various domains and extreme inclusion configurations confirm the formulation's robustness and efficiency.

Lattice metamaterials are widely optimized for compression-dominated applications, yet their tensile fracture resistance, often governing reliability in load bearing lightweight systems, remains far less understood. Here, we develop a bio-inspired variable-density toughening strategy for brittle triangular lattices by tuning the unit cell opening angle to program relative density and morphology without altering topology, and by embedding dense triangular subcells into a full triangular lattice to form heterogeneous architectures. A predictive scaling model is established for the effective tensile strength and modulus, and the tensile fracture and mode I crack propagation are quantified via validated finite element simulations of elastic brittle lattices. Increasing the opening angle systematically enhances tensile strength and stiffness, while the mode I toughness exhibits a consistent stretching-dominated density scaling. Introducing dense regions near the crack path promotes crack tip stress redistribution and delays catastrophic collapse. The first strut failure triggers stress redistribution rather than immediate global failure, evidencing an enhanced resistance to unstable crack propagation through stress redistribution induced by density contrast. Notably, the mode I fracture toughness of heterogeneous lattices follows a composite like mixture relation between the constituent lattices, enabling closed form estimates of fracture performance and revealing an optimal mixing range when normalized by weight. These results provide a mechanistic and quantitative route to designing lightweight lattice metamaterials with improved tensile damage tolerance for engineering deployment.

Gradient nanograined (GNG) architectures exhibit exceptional mechanical properties arising from their distinctive microstructure, whereas multi-principal element alloys (MPEAs) have attracted intensive scrutiny as a new class of advanced metallic materials. Nevertheless, reports on the materials that possess both GNG topology and multi-principal element composition remain absent. To bridge this knowledge gap, this paper presents a first investigation on the uniaxial tensile deformation of GNG CoCrNi MPEAs by means of quasi-three-dimensional molecular dynamics simulations. From a micro-mechanical perspective, the elastic-plastic deformation mechanism and grain boundary behavior are systematically delineated. The simulation results reveal that a portion of strain energy is dissipated through atomic phase transformation during the plastic deformation of the specimen, whereas larger grain size gives rise to higher intragranular deformation capability. Quantitative tracking of microstructural evolution demonstrates that grain boundary formation and annihilation proceed concurrently throughout straining, accompanied by pronounced grain boundary motion. Furthermore, a tendency of Cr segregation at grain boundaries is identified, which can be attributed to the atomic size misfit. These findings furnish understanding of the deformation mechanisms in GNG MPEAs and offer atomistic guidelines for the design of next-generation high-performance metallic materials.

Performance evaluation of facilities in flight area is a key factor affecting the safety of airport, and monitoring the infrastructures in real time and reporting the performance of the airport runway are critical for ensuring the airport in safe condition. However, traditional way of evaluating the airport infrastructure needs to shutdown the traffic, and cannot report the performance of airport infrastructure in real time. Nowadays, many airport authorities are trying to use multiple sensors to measure the properties of airport infrastructure in real time, but the performance evaluation parameters for the airport runway are still needed. This work proposed an airport digital runway construction method based on in-situ sensing data for potentially developing the airport runway performance evaluation parameters in a timely format. The method consists of obtaining real-time multisource state information of the runway through sensors, analyzing the runway evaluation indexes through the measured data, as well as the architecture and main functions of the digital runway system. The airport digital runway, constructed by using 3Ds Max + DATAV, can provide the performance information of runway and predict the potential risks of runway, which helps the airport runway management department to better understand the performance of airport runway. This result has been piloted at Chengdu Tianfu International Airport and greatly enhanced the ability to manage safety risks. (c) 2026 Tongji University and Tongji University Press. Publishing Services by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BYNC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

This study introduces a bio-inspired approach aimed at improving the abrasion resistance of Portland cement concrete (PCC) pavements. The method involves the in-situ precipitation of hydroxyapatite (HAP), the hardest mineral in the human body, on the concrete surface through repeated treatments with diammonium phosphate (DAP) solution. Experimental results demonstrate a significant reduction in mean profile depth (MPD) loss under accelerated wheel loading, with a remarkable 90.65% decrease after 90 000 wheel loads compared with the untreated surface. In the rotating wear test, mass loss was reduced by more than 50 %, following DAP treatment. Additionally, the compressive strength of the PCC increased notably, with a maximum improvement of 15.80 %, accompanied by a rise in surface Leeb hardness (LH). Importantly, the DAP treatment preserved both the friction coefficient and surface texture of the pavement, as evidenced by threedimensional (3D) texture mapping and field tests. Thermogravimetric analysis (TGA) confirmed the precipitation of HAP on the PCC surface through an in-situ reaction between DAP and calcium-rich minerals, primarily calcite, present in the concrete. Scanning electron microscopy (SEM) analysis revealed a denser microstructure, primarily attributed to the formation of HAP that fills the pores. As a result, significant increases in the average indentation hardness values of the concrete surface were observed after DAP treatment. Overall, this bio-inspired method proves highly effective in enhancing the abrasion resistance of PCC surfaces, thereby significantly extending the service life of PCC pavements. (c) 2026 Tongji University and Tongji University Press. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/bync-nd/4.0/).

Abstract Preceding investigations on the atomic dynamics in melts of Ti 75 Ni 25 revealed faster atomic dynamics as compared to that found in melts of Zr 64 Ni 36 and Ni 66.7 B 33.3 , despite the fact that all these melts are characterized by similar packing fractions. In order to find a structural explanation for the different dynamic behavior, we have studied the short-range structure of stable and undercooled Ti 75 Ni 25 melts. The melts were containerlessly processed under high-purity conditions by application of the electrostatic levitation technique. Partial structure factors of the liquid alloys have been determined by a combination of neutron diffraction (with isotopic substitution) and synchrotron x-ray diffraction. The studies reveal that Ti 75 Ni 25 melts are characterized by a chemical short-range order, where heterogeneous Ti-Ni nearest neighbors are preferentially formed. This chemical short-range order, however, is less pronounced than the chemical short-range order reported for melts of Zr 64 Ni 36 and Ni 66.7 B 33.3 . The less pronounced chemical short-range order may account for the faster atomic dynamics reported for liquid Ti 75 Ni 25 . For a further analysis of the structure-dynamics relationship the experimentally determined partial structure factors were used as an input for calculations in the framework of the mode coupling theory (MCT) of the glass transition. These reveal that the Ni self-diffusion is only slightly faster than the Ti self-diffusion with a ratio of the self-diffusion coefficients D Ni / D Ti ≈ 1.2. Moreover, the Onsager coefficients calculated by MCT are in good agreement with those estimated by use of Darken’s equation indicating that cross-correlation effects are negligible when describing the interdiffusion in liquid Ti 75 Ni 25 .