Low fracture toughness is one of the factors limiting the widespread applications of magnesium and its alloys. Mg17Al12 is a common precipitation phase in magnesium-aluminum-based alloys, and it favours crack nucleation in the experiment. While its effects on brittle and ductile crack-tip behaviours in magnesium are still lacking. This work examines the effect of Mg17Al12 phase on brittle and ductile crack extension behaviours in magnesium via atomic-scale 'K-field' loads simulation. The results show that the Mg17Al12 phase changes the brittle and ductile crack tip behaviours by affecting the distribution of the crack tip stress field. Under model I loading, the stress along the crack extension direction mainly concentrates at the interface of the Mg17Al12 phase and the matrix, which leads to a significant blunting of the crack tip geometry powered by the crack opening stress. For a ductile crack tip, the concentrated interfacial stress is mainly dissipated by dislocation nucleation, slip, void nucleation and growth. For a brittle crack tip, the concentrated interfacial stress is mainly dissipated by twin nucleation and void nucleation, growth, and cleavage along the matrix. This work presents the atomic-scale mechanisms of the effects of the Mg17Al12 phase on brittle and ductile crack tip activities in magnesium, which offer references for crack-tip activity analysis in magnesium-aluminum-based alloys.

Laser cleaning with a UV picosecond laser offers an effective solution for removing degraded radar absorbing coatings. This study systematically investigates the cleaning process, focusing on efficacy, substrate modifications, and removal mechanisms across a range of scanning speeds. Complete coating removal is achieved at 1500 mm/s, resulting in a clean surface with negligible oxidation. Lower scanning speeds result in spherical microstructures and coating residue, whereas extensive ablation prevails at 500 mm/s. The spherical microstructures increase surface roughness, which exhibits a non-monotonic dependence on scanning speed. At 1000 mm/s, surface roughness peaks at 2.52 mu m, accompanied by a contact angle of 46.86 degrees and a surface energy of 55.20 mJ/ m2. Corrosion resistance, determined by both wettability and microstructure, is worst at this speed and optimal at 1500 mm/s. The removal mechanism shifts from predominantly photochemical decomposition and plasma shock at 1500 mm/s to progressively dominant thermal ablation at lower speeds. At 500 mm/s, thermal ablation becomes the dominant mechanism, leading to coating carbonization and substantial residue formation. Notably, the near-surface crystal structure of the substrate remains unaltered after processing at the optimal speed of 1500 mm/s, confirming the negligible internal impact of the UV picosecond laser cleaning process.

Medium-entropy superalloys (MESAs) are effective candidates for next-generation wrought superalloys, yet their hot deformation behavior is not well understood. In this study, a novel MESA was subjected to isothermal compression tests over a wide range of temperatures (1040-1200 degrees C) and strain rates (0.01-10 s_ 1). The microstructures resulting from these varied deformation parameters were then systematically characterized and analyzed. It was found that the gamma' solvus temperature acts as a critical threshold, fundamentally governing microstructural evolution. Below the solvus, the strong pinning effect of the gamma' phase, combined with twins, provided multiple nucleation sites. This activated a complex interplay of discontinuous dynamic recrystallization (DDRX), continuous dynamic recrystallization (CDRX), particle-stimulated recrystallization (PSN), and twinninginduced recrystallization (TDRX), resulting in an ultrafine-grained structure. Conversely, above the solvus, recrystallization proceeded via a combination of DDRX and CDRX, making the final grain size highly sensitive to the thermomechanical parameters. This research advances the fundamental understanding of microstructure evolution and its associated deformation mechanisms in MESAs during hot deformation, providing critical guidance for optimizing the microstructure and mechanical properties of MESAs.

Aluminum alloy micro-grooved miniature heat pipes offer significant advantages for dissipation of high heat flux densities in confined spaces within thermal management systems of electronic equipment in aerospace and other fields, owing to their high thermal conductivity, miniaturization, and lightweight properties. However, the insufficient capillary performance of the micro-grooved wicks in aluminum alloy miniature heat pipes has become a key factor limiting their heat transfer efficiency. This study addresses the enhancement of capillary performance in aluminum alloy heat pipes by proposing a self-sealing hydrothermal process (SSHP) to construct micro/nanostructures on the surfaces of micro-grooved heat pipes, thereby improving capillary performance. The study investigates the ways in which the SSHP process affects aluminum alloy surface wettability and the underlying mechanisms, analyzes the effects of SSHP process parameters on the capillary performance of aluminum alloy micro-grooved miniature heat pipes, and optimizes these parameters. The results demonstrate that SSHP treatment induces a superhydrophilic transformation on the aluminum alloy surface, strongly correlated with the shape characteristics of the constructed surface nanostructures. A smaller average aspect ratio and longer average length of boehmite nanostructures correlate with increased hydrophilicity of the aluminum alloy surface. Following SSHP treatment, the capillary performance of aluminum alloy micro-grooved heat pipes increases by up to 2679%. The mechanism behind this enhancement is elucidated, and optimal SSHP process parameters for aluminum alloy micro-grooved heat pipes are proposed. This study provides theoretical and technical support for the fabrication of high-capillary-performance aluminum alloy miniature heat pipes.

For environmental protection, and for the exploration of size effects of friction in micro-forming, diamond-like carbon (DLC) has been gaining increasingly more attention as a candidate for substituting for conventional lubricants on account of its excellent tribological properties. Silicon-doped DLC, nano-laminated DLC, DLC with gradient properties, etc. have been developed to change and enhance its properties. The small dimensions of the micro-die cavities used in micro-forming have obvious effects on the surface topography and mechanical properties of DLC. Micro-sheet-forming experiments, such as strip drawing, bending, and deep drawing, have show that DLC can bear high contact stress and strain, improve the micro-forming properties, e.g., the limiting drawing ratio, and extend the working life of coated tools under dry condition. In micro-bulk forming, DLC can be used to reduce the forming load in micro-extrusion, and protect the template in respect of antiadhesion properties in nano-printing. In this paper, a model is introduced for analyzing the wear mechanism of DLC from the viewport of graphitization, by considering frictional work.

The next generation of space-based gravitational wave observatories, such as LISA, TianQin, and Taiji, requires ultra-precise drag-free control and therefore micro-propulsion systems with thrust noise below 0.1 mu N/Hz. This paper presents the design and experimental validation of a high-precision pressure regulation unit (PRU) for cold-gas micro-propulsion, guided by a requirement-driven analysis of pressure-induced thrust-noise sensitivity. A first-order mapping translates the mission-level thrust-noise constraint into a subsystem-level pressure-stability target, yielding an upper bound of about 50Pa/Hz and an adopted design budget of about 40Pa/Hz. On this basis, a dual-stage architecture integrating solenoid pre-conditioning and piezoelectric fine regulation is developed. Stochastic simulations indicate that thermal drift dominates at very low frequency, whereas pressure fluctuation is the dominant contributor in the main 0.01-1Hz control band under the adopted budget. Experimental validation under three operating modes shows that solenoid-only regulation provides the smallest performance margin, that the piezoelectric stage significantly improves outlet stability, and that the integrated dual-stage configuration achieves the strongest pressure-noise suppression in the mission-relevant sensitive band. These results provide a subsystem-level pressure-conditioning basis for the further development of high-precision cold-gas micro-propulsion systems for future drag-free missions.

Laser cleaning provides a green and efficient method for cleaning oxide films from aluminum alloys. This study systematically investigated the surface state and chemical composition specimens after laser cleaning with different laser fluence. By combining scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), an evaluation criterion for assessing oxide film removal on aerospace aluminum alloys was established. This criterion was used to develop cleaning processes and determine cleaning and damage threshold. The optimal cleaning parameters were identified, and the underlying removal mechanisms were analyzed. The results demonstrated that at a 70% overlap rate, the cleaning threshold was measured at 3.82 J/cm2. The optimum state was achieved at 7.64 J/cm2, while the damage threshold was 11.46 J/cm2. At the damage threshold, the surface exhibited severe melting and crack formation, leading to substrate damage. The removal mechanism was closely related to laser fluence (F). At lower laser fluences, the dominant mechanism was likely associated with laser-induced phase explosion. As the fluences increased, the mechanism transitioned to predominantly laser ablation. At even higher laser fluences (F), laser-induced evaporation became predominant. This study may provide valuable insights for the application of laser cleaning in the pre-weld treatment of aerospace aluminum alloys.

To address the issue of inferior formability for titanium alloy sheet at room temperature with a relatively higher efficiency, we proposed induced current-assisted forming and carried out the corresponding basic research. With finite element simulation and experiments, the bending property improves as the coil current increases. At the maximum coil current (18A), the bending load drop and springback angle reach 815.15N and 25°, respectively, which reflects the optimal bending property in this research. The corresponding evolution in bending behavior depends on the stress state and dislocation motion. With the adequate thermal effect provided by the induced current, refined grains after recrystallization appear, and dislocation density decreases. This induced a load drop and stress reduction in the bending part. Meanwhile, the shape of grains, distribution of dislocations, and activation of the slip systems contribute to the increasingly active dislocation motion during bending, which enhances the plastic deformation. With the contribution of enhanced plastic deformation and reduced stress, the springback of the sheet can be effectively relieved. Therefore, the feasibility of the approach proposed has been validated.

The ultra-thin flat heat pipe (UTFHP) wick with an arrayed microchannel structure represents an ideal choice for next-generation spacecraft in extreme thermal management applications. It is challenging to achieve efficient, high-precision, and low-cost arrayed microchannel processing using conventional manufacturing techniques. The electrically assisted micro-rolling (EAMR) technology proposed in this study demonstrates significant advantages in the fabrication of array microchannels on pure titanium sheets. At the outset, EAMR experiments were performed at varying current densities using the developed equipment. Subsequently, the effects of current density on microchannel surface quality, filling behavior, and microstructural evolution in the filling zone were examined, thereby revealing the mechanism behind the enhanced filling performance. The results show that higher applied current densities sharply define the edges of microchannel valleys and ridges, with filling capacity increasing as current density rises. The microchannels exhibited a uniform structure, straightness, and no significant defects. The applied current density markedly increased filling height while substantially improving microchannel uniformity and symmetry, with filling performance at rounded corners gradually improving. Electron backscatter diffraction (EBSD) analysis revealed that the average grain size in the filling zone was significantly smaller than that in the initial sheets. As the current density increased, the coordinated deformation capability between grains improved, the proportion of twins decreased markedly, and dislocation slip characteristics gradually became more pronounced. Pronounced dynamic recovery occurred, with grain sizes in various regions gradually growing. In the filling zone of pure titanium, the Schmid factor (SF) of non-base plane slip markedly increased, while the slip capacity of pyramidal and prismatic slip was enhanced. Non-base plane texture gradually became dominant, with corresponding non-base plane slip emerging as the primary deformation mode in pure titanium. This study provides experimental and theoretical foundations for the efficient manufacture and application of water-filled titanium UTFHP wicks.

Airport runways are the lifeline of the aviation industry, and their maintenance plays a crucial role in ensuring flight safety. How to thoroughly remove the stubborn aircraft tire tread rubber layer under extreme working conditions (rainy/snow season) while ensuring the integrity of the cement or asphalt runway surface structure is an urgent technical challenge that needs to be overcome in the field of runway maintenance. This paper conducts laser rubber layer of different thicknesses removal tests on runways with different base structures (cement/asphalt) using nanosecond pulsed lasers under various laser conditions (power/spot overlap rate) and surface dry or wet states (sunny weather/rainy season/post-snow conditions). The laser rubber removal process database under different weather conditions was obtained using an optical microscope, high-speed camera, and pendulum friction coefficient tester, revealing the coupling mechanisms of laser ice breaking and water hazard penetration to remove rubber. The mapping relationship between the cleaning mechanism and laser conditions, rubber deposition thickness, and cleaning effect was established. There is a linear relationship between the laser ablation depth (Y) and the logarithm of laser energy (X): Y= 1.1X-0.31. The initial cleaning threshold for rubber deposition is 0.28 J/cm2, and under sunny conditions, chemical combustion removal accounts for 2.24 % - 33.4 % of the entire removal mechanism, with optical thermal ablation mechanism dominating. Under the unit area (1 cm2), the laser energy consumed by 1 mm of ice layer is 1.8 J/cm2. Under the action of the laser, the upper surface of the ice layer is melted, and the remaining laser passes through the ice layer and melts the bottom by heating the rubber deposit. Under the rainy season conditions, the plasma plume area decreases, the interaction between the pulsed laser and rubber deposition weakens, and the damage to the runway is reduced under the same laser flux, but it is not sufficient to completely avoid the excessive thermal effects. The research results can provide a solution to the safety dilemma of airport operations during rainy and winter seasons, and promote the construction of ''safe, green, and smart'' airports.

Efficient and high-quality continuous production of glass micro-structure elements meets significant application requirements in various fields such as electronics, architecture, medicine, automotive and optics. The roll-to-plate (R2P) hot embossing process is a promising and cost-effective manufacturing technique for the rapid fabrication of high-quality and large-area glass micro-structures. However, the filling deformation of glass during the R2P hot embossing process is complex due to the unique contact interface between mold and glass, as well as the viscoelastic characteristic of softened glass. To reveal the deformation characteristics and filling pattern of glass during R2P hot embossing process, a controlled variable method test with 3 factor 5 level was conducted in the home-made machine. The sensitivity of processing parameters (roller temperature, roller speed, and roller pressure) for the surface morphology of the rolled glass was analyzed. The deformation profiles and defect evolution of glass micro-structures under different process conditions were investigated using scanning electron microscopy (SEM) and white light interferometry. The experimental results demonstrated that the height of the micro-structures exhibited a positive correlation with the roller temperature and embossing force, and an inverse correlation with the embossing speed. The experimental results show that the interface friction behavior of the glass mold in the R2P hot embossing process can be reflected by the roller torque. The low embossing speed, high embossing temperature, and high embossing speed will all lead to interface instability. The microstructure formation types under different process parameters are summarized as flat-peak-filled pattern, curvature-peak-filled pattern, bump-filled pattern. This work provides a theoretical guidance for the efficient and high-quality production of glass microstructures.

Superelastic degradation (SED), a progressive loss of functionality in NiTi shape memory alloys under cyclic loading, remains challenging to characterize precisely, thereby constraining their engineering applications and broader adoption. In this study, an interpretable learning framework was proposed to predict the SED of NiTi alloys and uncover the degradation mechanisms using interpretability analysis methods. The framework incorporates multi-source microstructure and loading conditions through a multi-branch architecture that effectively decouples and integrates heterogeneous features, achieving an R2 of 0.981. The competition between slip and transformation was identified: at high amplitudes, SED is dominated by transformation regions with high Schmid factors, whereas at low amplitudes, dislocation slip on the {011}〈001〉 and {011}〈111〉 systems prevails. Subsequently, the influence of Ni4Ti3 precipitates was quantified, revealing a loading-dependent and non-uniformly beneficial role. The results highlight the potential of interpretable machine learning in exploring the cyclic deformation process and pave the way for AI-driven research on smart materials. This manuscript highlights an interpretable learning framework to explore superelastic degradation in NiTi alloys, revealing mechanisms linked to grain orientation and Ni4Ti3 precipitates, and promoting data-driven design of shape memory alloys.

Die forging inevitably induces metal flow toward both the die cavity and flash, leading to the formation of a flow boundary between these two regions. However, the influence of such a flow boundary on the final microstructure and properties of forgings remains unclear. To address this gap, this study investigates the effects of flow boundaries on the microstructure and mechanical properties of disk-shaped 7075 aluminum alloy casing forgings via a combination of finite element (FE) simulations and experimental characterizations. Results show that two distinct flow boundaries form at different locations during disk forging, and their formation mechanisms and evolutionary characteristics were systematically clarified. Electron Backscatter Diffraction (EBSD) analysis revealed significant microstructural inhomogeneities at different locations of the forging: regions adjacent to flow boundaries (Locations 2 and 3) exhibit coarse grain structures with an average grain size of 54.02 µm and 32.70 µm, and low recrystallization fractions of 22.7% and 31.9%, which are only half of those in non-boundary regions (48.8%–51.9%). Tensile tests demonstrated that the yield strength of flow boundary regions in the radial direction is 362 MPa–371 MPa, which is 40 MPa–50 MPa lower than that of non-boundary regions (400 MPa–413 MPa). Although flow boundaries have a significant impact on grain morphology and texture development, they exert only a minor effect on phase distribution and texture intensity. These quantitative findings offer critical theoretical support for optimizing the forging processes of high-performance aluminum alloy components and improving the uniformity of forging properties.

Radar absorbing coatings are prone to damage in harsh operating environments, requiring prompt removal and repair to maintain their functionality. In this study, radar absorbing coatings on roughened aluminum alloy surfaces were successfully cleaned using a UV picosecond laser, with the influence of different energy densities on surface integrity and overall performance systematically analyzed. The optimal laser cleaning energy density is determined to be 2.41 J/cm2, enabling complete removal of radar absorbing coatings while maximally preserving original substrate morphology and minimizing oxidation. At 3.03 J/cm2, spherical microstructures form on the surface, evolving into cluster protrusions at 3.66 J/cm2. Only a 5 nm amorphous oxide layer forms on the surface after laser cleaning at 2.41 J/cm2. When the laser energy density increases to 3.66 J/cm2, this layer thickens to 8 nm with spherical oxide particles in the near-surface region, while the overall cross-sectional microstructure remains unchanged. These changes in morphology, composition, and microstructure significantly influence surface performance. While higher energy density improves hardness and wear resistance, excessive energy density leads to a decline in corrosion resistance. Particularly, UV picosecond laser cleaning only modifies the near-surface layer of the substrate, leaving the internal phase composition, microstructure and bulk mechanical property virtually unaffected.

For water-filled titanium ultra-thin flat heat pipes (UTFHPs), superior wick performance is essential to ensure efficient operation and prevent dry-out. In this study, rectangular microgroove wicks were fabricated by electrically assisted micro-rolling, followed by hydrothermal treatment, acid pickling, and calcination to construct TiO2 nanostructures on the microgroove surfaces. The results show that pure titanium was successively transformed from Na2Ti3O7 to H2Ti3O7 and finally to TiO2. With increasing NaOH concentration, the TiO2 morphology evolved from relatively loose structures to denser coverage, while W100-5 exhibited more open and interconnected nanoscale pores. Surface wettability and XPS analyses showed that abundant surface-OH groups on TiO2 promoted water adsorption and spreading, resulting in excellent hydrophilicity. The capillary rise behavior was characterized by high-speed imaging, and the maximum average wicking velocity and capillary performance parameter (K/Reff) reached 18.33 mm/s and 3.41 mu m, respectively, corresponding to 280% and 741% of those of the untreated wick. Stability tests further showed that the TiO2 nanostructures and primary microgroove morphology were generally maintained after vacuum storage, ambient aging, and 90 degrees C water flushing, while the main capillary enhancement effect was retained. The proposed "plastic microformingchemical modification" strategy enhances the capillary performance of titanium wicks while maintaining the wick thickness within 75-240 mu m, showing potential for UTFHPs applications.

To address interfacial delamination of spacecraft thermal control coatings, this study employs laser texturing to construct controllable surface microstructures on aluminum alloy substrates. Process parameters were optimized using Taguchi experimental design, and surface morphology evolution was analyzed through combined experiments and numerical simulations. Results show that single pulse energy is the dominant factor governing surface roughness and microstructural features. As laser energy increases, micro-pits deepen and splashing intensifies, while the substrate microstructure remains stable. Finite element simulations identify 0.80 mJ as the critical threshold at which the governing mechanism transitions from heat conduction to evaporation–recoil dominance. At 1.00 mJ, enhanced inertial flow further reshapes pit geometry, maximizing mechanical interlocking despite a slight reduction in surface polarity. Higher laser energy also drives the transformation of the surface oxide from a hydroxyl-rich porous layer to a denser alumina film, significantly improving surface hydrophilicity. Stress analysis of droplet spreading confirms that the textured morphology induces stress concentration and retention, indicating mechanical interlocking as the primary adhesion mechanism. The enhanced coating adhesion is attributed to the synergistic effects of mechanical anchoring, geometric interlocking, and laser-induced surface activation. This work clarifies the multiphysical mechanisms underlying laser-textured interfacial strengthening for reliable thermal control surface design.

Electrically assisted forming (EAF) introduces electric current to induce Joule heating and the electroplasticity effect, thereby reducing the deformation resistance while improving the plastic deformation capability of materials. This provides a promising route for the high-precision forming of high-strength aluminum alloys. In this study, the electrically assisted tension (EAT) behavior of 6061-T651 aluminum alloy under different current densities was systematically investigated, with particular emphasis on the correlation among Joule heating, local strain evolution, microstructural evolution, and fracture behavior. The results show that the Joule heating effect was significantly enhanced with increasing current density, leading to a nonlinear increase in the peak temperature of the specimen. Meanwhile, both the flow stress and ultimate tensile strength (UTS) were markedly reduced. The elongation first increased and then decreased with increasing current density, reaching its maximum value at 250 A/mm2. Digital image correlation (DIC) results revealed that the applied electric current promoted strain localization in the central region of the gauge section. Fractographic analysis showed that EAT gradually changed the fracture behavior of 6061-T651 aluminum alloy from quasi-cleavage features to ductile fracture. Electron backscatter diffraction (EBSD) results demonstrated that the applied electric current weakened the tensile deformation texture. Transmission electron microscopy (TEM) observations further revealed that the electric current facilitated dislocation depinning, rearrangement, local recovery, and the dissolution or refinement of Mg–Si precipitates. Overall, the improved formability of 6061-T651 aluminum alloy during EAT cannot be attributed solely to thermal softening, but results from the combined effects of Joule heating and electron-dislocation interaction.

Developing precision forming of magnesium alloy micro-grooved heat pipes is of great significance for improving the lightweight level of aerospace thermal management systems. In this paper, the electrically-assisted extrusion of magnesium alloy heat pipes is explored, and the effects of extrusion and electrical parameters on the forming accuracy, microstructures, and mechanical properties are studied. Finite element simulation found that electrifying the extrusion ram and preheating the extrusion cylinder could effectively ensure the billet temperature, and an extrusion window (30–60 s) could be obtained. Reducing the extrusion velocity and increasing the current could both reduce the extrusion load. Within the range of the studied parameters, the micro-grooved heat pipes are relatively fully formed. It is found that increasing the extrusion velocity and electrical parameters would increase the grain size of the magnesium alloy. While the electrical parameter increases from 0 to 300 A, the grain size increases from ∼5.9 to ∼12.6 µm, and the tensile strength and yield strength of the extruded profiles are also 20.7

V-shaped riblets are widely studied shark-skin-inspired microstructures, but their continuous high-fidelity replication on soft hyperelastic substrates remains challenging because large substrate deformation complicates complete profile filling. This study establishes an Abaqus-based finite-element process-window and morphology-screening method for roll-to-roll (R2R) hot embossing of 100 μm-scale V-shaped riblets on a fluoroelastomer (FKM) sheet as a model hyperelastic substrate. A Yeoh hyperelastic law calibrated from room-temperature uniaxial tension was implemented in a three-dimensional large-deformation contact simulation. Embossing temperature T and imposed nip-compression depth D were examined as screening variables, with formed riblet height, filling ratio, and auxiliary field indicators used to evaluate the forming response. The simulated filling ratio increased from about 69% to 76% as T increased from 120 to 180 °C and from about 39% to 76% as D increased from 60 to 120 μm, indicating that nip-compression depth exerted the stronger geometric control over profile filling. R2R hot embossing experiments and laser-confocal profilometry evaluated the retained riblet morphology. For the 160 °C D-series, the measured retained morphology followed the simulated filling trend, with a filling-ratio RMSE of 3.09 percentage points and top-width RMSE of 2.01 μm. The integrated numerical-experimental framework provides an experimentally supported manufacturing basis for process-window selection and retained-morphology control in the R2R hot embossing of riblet-textured hyperelastic sheets.