Aerospace Equipment Research Articles

First-principles investigation of oxygen repulsion behavior on the Ir–Hf alloy surface

Enhancing the oxidation resistance of hot-end components under extreme conditions is a key focus in aerospace equipment research. We used first-principles simulations to investigate a series of IrxHf100−x (at. %) coatings. By employing density functional theory and the local density approximation method, we studied the surface oxygen repulsion energy and estimated the optimal composition ratio of IrxHf100−x for the strongest oxidation resistance. The results indicate that as the Hf content increases, the oxygen repulsion energy first rises and then falls, reaching a maximum value of 3.04 eV at x = 10 at. %, with active oxygen adsorption occurring when X exceeds 45 at.%. To understand the mechanism of the oxygen repulsion process, we analyzed the electronic characteristics between Ir, Hf, and O. O preferentially hybridizes its atomic orbitals with Ir, and the improvement in oxidation resistance of the Ir–Hf coating is attributed to the reduction in Ir atomic spacing due to Hf doping, which reduces O–Ir orbital hybridization.

The Microstructure and Wear Properties of Ni-coated and Agglomerated-Sintered WC-10Ni/316 Composite by Laser Melting Deposition

WC-10Ni particle-reinforced stainless steel matrix composites have potential applications in aerospace, energy engineering, automotive manufacturing, and marine engineering equipment. However, there is currently insufficient research on the integrated manufacturing and comparative analysis of Ni-coated (WC-10Ni)1.5/316 and agglomerated-sintered (WC-10Ni)1.5/316 composites using Laser Melting Deposition (LMD) technology. In this work, the fabrication and examination of the LMDed specimens are conducted to determine the influence of the forming process of particle reinforcement on the microstructure and wear properties of WC-10Ni/316 composites. The microstructure, phase composition, composition distribution, microhardness, and wear resistance of the two composites were comparatively analyzed using confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), microhardness tester, X-ray diffraction(XRD), energy-dispersive spectroscopy (EDS), and a reciprocating wear tester. The results indicate that the microstructure of Ni-coated (WC-10Ni)1.5/316 composite specimen contains a higher quantity of undecomposed Ni-coated WC-10Ni particles, with a lower proportion of precipitates, and dendrites predominantly exhibit an elongated dendrite morphology. In contrast, the agglomerated-sintered (WC-10Ni)1.5/316 composite specimen features a greater content of decomposed agglomerated-sintered WC-10Ni particles, a higher content of precipitates, and dendrites mainly present as slender dendrites. Both composites consist of phases such as γ-(Fe, Ni, Cr), WC, W2C, Fe6W6C, M6C, and Cr23C6. The undecomposed WC-10Ni particles and tungsten precipitates significantly enhance the microhardness and wear resistance of the specimen. Specifically, the Ni-coated (WC-10Ni)1.5/316 composite specimen displays a microhardness of 350.2±3.3 HV1.0, with a wear rate of 1.5797±0.0455mg/(N·km). Meanwhile, the Agglomerated-sintered (WC-10Ni)1.5/316 composite specimen reveals an average microhardness of 410.9±6.1 HV1.0 and a wear rate of 0.8057±0.0352mg/(N·km).

Concurrent multi-scale design optimization of fiber-reinforced composite material based on an adaptive normal distribution fiber optimization scheme for minimum structural compliance and additive manufacturing

Structural lightweight is a core technical requirement for the structural design of aerospace and new energy power equipment structures. For multi-scale variable stiffness design optimization of discrete fiber-reinforced composite laminates, one of the challenges is how to avoid the explosion of design variable combinations caused by the increase in the number of candidate discrete fiber laying angles. The Normal Distribution Fiber Optimization (NDFO) interpolation scheme has the numerical advantage that the number of design variables does not increase with an increase in the number of candidate discrete fiber laying angles. However, the traditional NDFO interpolation scheme uses uniform penalty parameters across all elements, which means that normalizing the penalty parameters for all the elements ignores the convergence differences of discrete fiber laying angles in different elements within the macro-scale structure topology. This leads to time-consuming and unstable optimization iteration of the macro-scale structural topology and micro-scale discrete fiber laying angle selection. Especially, it easily causes the micro-scale discrete fiber laying angle selection to fall into the local optimum prematurely. Therefore, considering the difficulties and challenges of the traditional NDFO interpolation scheme in the multi-scale variable stiffness design optimization of fiber-reinforced composites. This paper proposes an Adaptive Normal Distribution Fiber Optimization (ANDFO) interpolation scheme, and the feedback mechanism of the convergence rate of the element design variable and the objective function is introduced to achieve the adaptive reduction of the penalty parameters. Based on the proposed ANDFO interpolation scheme, a multi-scale design optimization model of fiber-reinforced composite laminates is established, considering the macro-scale structure topology and micro-scale discrete fiber laying angel selection. The explicit sensitivity of the objective function of minimizing structural compliance to the macro-scale topological design variables and the micro-scale fiber laying angle design variables is derived. Considering the manufacturability of additive manufacturing based on the optimized design results, a multi-scale nonlinear continuous filtering strategy for discrete fiber laying angle is adopted to improve the continuity of the local fiber laying path. Numerical examples systematically present the coupling effects of macro-scale structural topology and micro-scale fiber laying path, multi-scale nonlinear discrete fiber continuous filtering laying path structure, and continuous fiber additive manufacturing multi-scale optimized structure. The proposed ANDFO scheme provides a new theoretical and methodological approach for the lightweight and integrated multi-scale design and manufacturing of fiber-reinforced composite laminates through additive manufacturing technology.

Mechanics of peeling adhesives from soft substrates: A review

Abstract Understanding peeling behavior in soft materials is integral in diverse applications, from tissue engineering, wound care, and drug delivery to electronics, automotive, and aerospace equipment. These applications often require either strong, permanent adhesion or moderate, temporary adhesion for ease of removal or transfer. Soft adhesives, especially when applied on soft substrates like elastomer-coated release liners, flexible packaging films, or human skin, present unique mechanical behaviors compared to adhesives applied on rigid substrates. This difference highlights the need to understand the influence of substrate rigidity on peeling mechanics. This review delves into both energy and stress-based analyses, where a thin tape with an adhesive layer is modeled as a flexible beam. The energy analysis encompasses components like the energy associated with tape deformation, kinetic energy, and energy lost due to interfacial slippage. The stress analysis, on the other hand, zeroes in on structures with thin, deformable substrates. Substrates are categorized into two types: those undergoing smaller deformations, typical of thin soft release liners, and thicker deformable substrates experiencing significant deformations. For substrates with small deformations, the linear Euler-Bernoulli beam theory is applied to the tape in the bonded region. Conversely, for substrates experiencing significant deformations, large deflection theory is utilized. These theoretical approaches are then linked to several practical, industrially-relevant applications. The discussion provides a strategic guide to selecting the appropriate peeling theory for a system, emphasizing its utility in comprehending peeling mechanisms and informing system design. The review concludes with prospective research avenues in this domain.

Aerospace Equipment Fault Diagnosis Method Based on Fuzzy Fault Tree Analysis and Interpretable Interval Belief Rule Base

The stable operation of aerospace equipment is important for space safety, and the fault diagnosis of aerospace equipment is of practical significance. A fault diagnosis system needs to establish clear causal relationships and provide interpretable determination results. Fuzzy fault tree analysis (FFTA) is a flexible and powerful fault diagnosis method, which can deeply understand causes and fault mechanisms. The interval belief rule base (IBRB) can describe uncertainty. In this paper, an interpretable fault diagnosis model (FFDI) for aerospace equipment based on FFTA and the IBRB is presented for the first time. Firstly, the initial FFDI is constructed with the assistance of FFTA. Second, a model inference is implemented based on an evidential reasoning (ER) parsing algorithm. Then, a projection covariance matrix adaptive evolutionary strategy algorithm with an interpretability constraints (IP-CMA-ES) optimization algorithm is used for optimization. Finally, the effectiveness of the FFDI is verified by a flywheel dataset. This method ensures the completeness of the rule base and the interpretability of the model, avoids the problem of exploding certain combinations of rules, and is suitable for the fault diagnosis of aerospace equipment.

Enhancing Engine Cylinder Heat Dissipation Capacity Through Direct Optimization (DO) Techniques

Internal combustion (IC) engines are used widely as the primary power source for automobiles of all types, cars, motorcycles, and trucks. Because of the high combustion temperatures involved in the operation, the excess heat is removed by means of extended fins that increase the surface area for adequate cooling. Significant improvement in the heat dissipation characteristics of the engine cylinder can be achieved by optimizing the design of these fins. The aim of this study is to evaluate the thermal performance of engine cylinder fins using an analytical system of finite element analysis (ANSYS FEA) software, using a direct optimization (DO) approach to identify optimal fin design. Analysis shows that fin length and width play critical roles in improving cooling efficiency, lowering the maximum temperature within the cylinder to 549.46 K and enhancing total heat flux to 7225.31 W/m2, which is a 25.87% increase from the generic design, capable of heating removal of 5740.22 W/m2. The current fin design is effective but could be improved in heat dissipation, mainly at fin tips. To optimize thermal performance while minimizing material costs, a balanced fin dimension is recommended. Alternative materials, transient heating analysis, and experimental verification may be examined in the future to achieve a total understanding of fin geometry and behavior under real operating conditions. These insights lay a foundation to accelerate cooling systems development in the automotive, aerospace, and heavy equipment industries, where efficient heat transfer is key for performance and long-term durability.

Free vibration characteristics of honeycomb sandwich cylindrical shells reinforced with graphene nanoplatelets/polymer coatings

This study conducts a comprehensive analysis of the free vibration characteristics of honeycomb sandwich cylindrical shells reinforced with graphene nanoplatelets (GNPs). The shells are modeled with a hexagonal honeycomb core, which not only provides a lightweight structure but also enhances the stiffness and dynamic stability. This core design is ideal for high-performance applications such as aerospace and light transport equipment. In addition, the incorporation of graphene nanoplatelet/polymer coatings further improves the structural stiffness, making these shells suitable for demanding environments where both strength and lightweight properties are critical. In the theoretical model, the refined trigonometric shear deformation theory (RTSDT) is applied to accurately represent both bending and shear deformations, capturing the complex behavior of honeycomb sandwich cylindrical shells without requiring shear correction factors. Various parameters, including axial and circumferential wave numbers, as well as geometry and material properties, are examined to assess their impact on natural frequencies. Comparisons with existing literature validate the theoretical models, demonstrating strong agreement with previous results. The analysis reveals that the fundamental natural frequency and other natural frequencies are significantly affected by the inclusion of GNPs and variations in sandwich cylindrical shell geometry. The findings underscore the effectiveness of the RTSDT in modeling these complex sandwich structures.

Opportunities and Challenges for Predicting the Service Status of SLM Metal Parts Under Big Data and Artificial Intelligence.

Selective laser melting (SLM) technology is a high-end dual-use technology that is implemented in aerospace and medical equipment, as well as the automotive industry and other military and civilian industries, and is urgently needed for major equipment manufacturing and national defense industries. This paper examines the challenges of uncontrollable service states and the inability to ensure service safety of SLM metal parts under nonlinear and complex operating conditions. An overview of the prediction of the service status of SLM metal parts was introduced, and an effective approach solving the problem was provided in this paper. In this approach, the cross-scale coupling mechanism between mesoscopic damage evolution and macroscopic service state evolution is clarified by tracking the mesoscopic damage evolution process of SLM metal parts based on ultrasonic nonlinear responses. The failure mechanism is organically integrated with hidden information from monitoring big data, and a "chimeric" model to accurately evaluate the service status of SLM metal parts is constructed. Combining nonlinear ultrasound technology with big data and artificial intelligence to construct a "chimeric" model and consummate the corresponding methods and theories for evaluating the service status of SLM metal parts is an effective way to reveal the mesoscopic damage evolution and service status evolution mechanisms of SLM metal parts under complex factor coupling, and to accurately describe and characterize the service status of parts under complex operating conditions. The proposed approach will provide a theoretical basis and technical guarantee for the precise management of SLM parts' service safety in key equipment fields such as aerospace, medical equipment, and the automotive industry.

Crystal Chemistry at Interfaces Between Liquid Al and Polar SiC{0001} Substrates

Silicon carbide (SiC) has been widely added into light metals, e.g., Al, to enhance their mechanical performance and corrosion resistance. SiC particle-reinforced metal matrix composites (SiC-MMCs) exhibit low weight/volume ratios, high strength/hardness, high corrosion resistance, and thermal stability. They have potential applications in aerospace, automobiles, and other specialized equipment. The macro-mechanical properties of Al/SiC composites depend on the local structures and chemical interactions at the Al/SiC interfaces at the atomic level. Moreover, the added SiC particles may act as potential nucleation sites during solidification. We investigate local atomic ordering and chemical interactions at the interfaces between liquid Al (Al(l) in short) and polar SiC substrates using ab initio molecular dynamics (AIMD) methods. The simulations reveal a rich variety of interfacial interactions. Charge transfer occurs from Al(l) to C-terminating atoms (Δq = 0.3e/Al on average), while chemical bonding between interfacial Si and Al(l) atoms is more covalent with a minor charge transfer of Δq = 0.04e/Al. The prenucleation at both interfaces is moderate with three to four recognizable layers. The information obtained here helps increase understanding of the interfacial interactions at Al/SiC at the atomic level and the related macro-mechanical properties, which is helpful in designing novel SiC-MMC materials with desirable properties and optimizing related manufacturing and machining processes.

Fuze vibration reduction design based on high-speed rocket sled vibration effect

Abstract Rocket sled is one of the important methods to realize the performance test in fields such as aerospace and weapon equipment. In response to the extremely high overload phenomenon of the tested fuze system in rocket sled impact tests, this paper proposes a new method of fuze vibration reduction. By optimizing the layout and multi-layer potting of fuze shell and internal components, the influence of vibration effects on electronic components is effectively reduced. Comparative analysis of results is based on epoxy resin sealant potting, silicone rubber potting, or without additional protection, to further improve the safety and service life of internal key components and provide necessary structural reference for vibration reduction treatment in rocket sled tests.

Identifying the influence of pouring temperature, Al-RHA composition, and pattern thickness on the properties of Al-RHA composites produced by evaporative casting

This study investigated the effect of pouring temperature, Al-RHA composition and pattern thickness on fluidity length, surface roughness at Al-RHA composition (85:15, 80:20, 75:25) %, pouring temperature (650, 700, 750) °C, and pattern thickness (1, 2, 3, 4, 5, 6, 10) mm. The challenge in this study is to optimize the fluidity length and hardness but minimize the surface roughness and porosity of the composite. The results showed that raising the pouring temperature increased the fluidity length, surface roughness, hardness, and porosity. Higher pouring temperature caused an increase in fluidity length by 13.51–54.17 % when the temperature raised from 650 °C to 750 °C. This was accompanied by an increase in hardness by 1.96–10.69 %. However, higher temperature also resulted in increased surface roughness by 3.9–7.92 % and increased porosity by 1.3–3 %. The composition ratio of Al-RHA plays an important role in determining the physical and mechanical properties of the composites. Increasing RHA content tends to increase the fluidity length but increases the surface roughness, hardness, and porosity. The higher RHA content increases the fluidity length by 2.44–11.9 % and the hardness also increases by 1.26–12.87 %. However, the higher RHA composition also increases the surface roughness by 1.2–30.95 % and the porosity increases by 2–2.7 %. The larger pattern thickness increases the fluidity length by 10.53–60.42 %. Controlling the RHA content and pouring temperature is very important to improve the physical-mechanical properties of Al-RHA composites. The results have potential applications in industries that require special composite materials such as automotive, aerospace, machinery and agricultural equipment

Advancements in Key Technologies for Vibration Isolators Utilizing Electromagnetic Levitation

With the advancement of manufacturing, the precision requirements for various high-precision processing equipment and instruments have further increased. Due to its noncontact nature, simple structure, and controllable performance, electromagnetic levitation has broad application prospects in ultra-precision instruments and ground testing of aerospace equipment. Research on vibration isolation technology using electromagnetic levitation is imperative. This paper reviews the latest research achievements of three types of passive isolators and five active isolation actuators. It also summarizes the current research status of analytical methods for passive isolators and the impact of isolator layout. This study explores current isolators’ achievements, such as the development of passive isolators that generate negative stiffness and require mechanical springs for uniaxial translational vibrations, single-function actuators, and control systems focused on position and motion vibration control. Based on the current isolators’ characteristics, this review highlights future developments, including focusing on passive isolators for heavy loads and multi-axis isolation, addressing complex vibrations, including rotational ones, and developing methods to calculate forces and torques for arbitrary six-DOF movements while improving speed. Additionally, it emphasizes the importance of multifunctional actuators to simplify system structures and comprehensive control systems that consider more environmental factors. This provides significant reference value for vibration isolation technology using electromagnetic levitation.

Modelling Method and Meshing Characteristics of a Novel Curve-Surface Conjugate Internal Gear Drive

Space exploration has become a major focus in the field of technology, with gear transmissions in aerospace equipment playing a crucial role. In the extreme environment of space, gear transmissions face challenges like large temperature differentials, deformation and maintenance difficulties, which will severely impact transmission accuracy and service life. To meet the growing demands for high-performance gear transmissions with high transmission efficiency and error adaptability in the aerospace field, this paper proposes a novel curve-surface conjugate internal gear drive consisting of an involute internal gear and a curve-surface gear. The fundamental theory of curve-surface conjugation is introduced, and the construction method for curve-surface gear based on a selected contact path and meshing tube is presented. The analysis models including induced curvature, sliding ratio and tooth contact analysis with errors (ETCA) are simulated to evaluate the meshing characteristics. Additionally, prototypes are manufactured and experimental setups are established to validate the transmission performance. These results indicate that as the rotational speed increases, the transmission efficiency of the curve-surface conjugate internal gear drive improves, which is contrary to the trend observed in involute gear drives. And the transmission efficiency of the curve-surface conjugate internal gear drive surpasses that of the involute gear drive at higher rotational speeds. Moreover, this novel gear drive exhibits excellent error adaptability, maintaining intact contact paths and high transmission efficiency even in the presence of assembly errors. This study provides new ideas for the design and manufacture of high-performance gear transmissions from the perspective of spatial geometric elements.

Surface Transformation Of Ultrahigh-Temperature Ceramics HfB2-SiC-C(graphene) Under The Influence Of High-Speed Disossociated Nitrogen Jets

In order to study the promising potential of HfB2–30 vol % SiC ultrahigh-temperature ceramic materials modified with low amounts of reduced graphene oxide for the creation of aerospace equipment intended for use in N2-based atmospheres, the effect of high-speed dissociated nitrogen flow on it has been investigated. It has been established that under the chosen conditions of exposure during the stepwise increase of the anode power supply of plasma torch and, accordingly, the influencing heat flux, at certain parameters there is a sharp increase in the surface temperature from ~1750 to 2000-2100°C. At the same time, further increase of the heat flux has no obvious and proportional effect on the temperature of the sample surface, which may indicate its high catalyticity with respect to the reactions of surface recombination of atomic nitrogen. It is shown that the surface layers of the material undergo chemical transformation (removal of silicon-containing substances, formation of a new phase based on HfN), which is accompanied by a significant change in the microstructure (formation of dendrite-like structures), which affects the optical and catalytic characteristics of the surface.

Current status and challenges of lightweight design and manufacturing technology for aerospace structures

Lightweight technology refers to the technology of reducing the structural mass by optimizing materials, structures and manufacturing processes while meeting the requirements of structural performance. It has become one of the key technologies for the development of the new generation of aerospace equipment. This paper first analyzes the development history of lightweight technology. Secondly, from the perspectives of design principles, composition methods and optimization methods, three types of lightweight design methods are introduced: bionic structure design, cellular structure design and efficient topology optimization design. Then, from the perspective of lightweight manufacturing processes and modes, the application of additive manufacturing, collaborative manufacturing and composite material manufacturing in lightweight manufacturing of aerospace structures is explained. Finally, the challenges and future development of lightweight technology are discussed.

Enhancing mechanical properties of 2024-Aluminium Alloy Matrix Composite strengthened by Y2O3 ceramic particles

The development of high-strength, low-weight composite materials has been a high-priority demand in the structural, aerospace, automotive, renewable energy, and sports equipment sectors. Micro-particle size Yttrium oxide (Y2O3) has been utilized to enhance the microstructure and mechanical characteristics of the 2024-Al alloy. The stir-casting technique is employed to prepare 2024-Al alloy and aluminum matrix composites (AMCs) with different Y2O3 weight fractions (1 %, 2 %, and 3 %). Scanning electron microscope ESM with EDS analysis and optical microscope imaging have been used to assess the development in the microstructure of AMCs. Furthermore, optical microscope images have been analyzed by using image processing software, ImageJ to evaluate development in microstructure grain size. Vickers' micro-hardness, tensile strength, elongation, and wear-resistant tests were conducted to assess the mechanical properties of AMCs. AMC image analysis results demonstrated a significant reduction in microstructure grain size. The highest reduction in grain size was recorded when adding 2 wt. % of Y2O3, which was approximately 22.5 % smaller than that of the plain alloy. Other mechanical test results demonstrated an increase in the hardness and tensile strength of AMCs compared with the plain alloy by approximately 58 % and 116 %, respectively, upon the addition of 2 wt. % of Y2O3, also tensile test shows increasing of AMCs elongation at failure point with increasing Y2O3 content, 132 % upon adding 3 wt. %. Finally, wear tests show a decrease in the AMC wear rate with an increasing Y2O3 weight fraction compared to the plain alloy.

Microscopic impacts of ultrasonic vibration on interfacial strength of SiCp/Al composites

SiCp/Al composites are used in aerospace and deep-space exploration equipment because of their extremely high strength and thrust-to-weight ratios; however, the differences in the properties of the reinforcement and matrix materials in this type of composites have restricted their applications. The ultrahigh-frequency vibration characteristics of ultrasonic vibration processing technology can effectively solve the above bottlenecks, but the effect of high-frequency vibration on the interfacial properties of SiCp/Al composites is still unclear. The effects of ultrasonic vibration on the interface strength of composites were analyzed from a microscale perspective by means of single particle push-out Molecular Dynamics (MD) simulations and tests under different conditions. The results show that the interface strength is negatively correlated with particle size but positively correlated with ultrasonic amplitude, with a maximum increase of about 51% relative to no ultrasound. Brittle-plastic transition was observed on the surface of particles with high interface strength, and lateral microcracks due to stress concentration were present on the surface of particles with low interface strength. Higher strains and grain refinement were obtained for larger amplitudes, and stacking faults and tangle dislocations appeared on the side of the interface layer close to the Al matrix. The results provide potential insights to improve the micromechanical and mechanical properties of SiCp/Al composites, enhance the longevity of the materials, and realize the sustainable use of resources by expanding the efficient, precise, and clean machining of such materials.

TiO2-hBN nanocomposite coating with excellent wear and corrosion resistance on Ti6Al4V alloy prepared by plasma electrolytic oxidation

Hexagonal boron nitride (hBN) is recognized for its promising application prospects in anti-friction and corrosion resistance due to its self-lubrication and excellent impermeability to gases and liquids. In this study, the TiO2-hBN nanocomposite coatings are prepared via the liquid plasma-assisted particle deposition sintering (LPDS) technology, enabling compact and uniform growth of hBN on the Ti6Al4V surface. Results indicate that the dense and stable plasma at the coating/electrolyte interface facilitates the deposition and sintering of hBN particles, effectively filling surface defects and achieving a coating density of 86.7 %. The friction coefficient of the TiO2-hBN nanocomposite coating significantly decreases from 0.54 (titanium alloy) to 0.28, remaining stable even after 2000 sliding cycles. Compared to the substrate, the wear rate (4.3 × 10−4 mm3N−1 m−1) of nanocomposite coating drops by 70.8 %, which is primarily attributed to the self-lubricating property of hBN, reducing the frictional shear stress. Moreover, the TiO2-hBN nanocomposite coating also has excellent corrosion resistance due to the hBN sheet filling internal defects and inhibiting the corrosion reaction. All these merits render the LPDS technology competitive in expanding the severe service conditions of titanium alloys in aerospace and marine engineering equipment.

Pulsed Unipolar-Polarisation Plasma Electrolytic Polishing of Ni-Based Superalloys: A Proof of Conception

The enhanced performance of aerospace equipment drives parts development towards integration, complexity, and structural optimization. This advancement promotes metal near-net fabrication technologies like wire electrical discharge machining (WEDM) and 3D printing. However, the high initial surface roughness from WEDM or 3D printing poses significant challenges for the high-performance surface finishing required. To effectively reduce the surface roughness of the workpieces with high initial surface roughness, this paper proposes pulsed unipolar-polarisation plasma electrolytic polishing (PUP-PEP). The study examined the material removal mechanisms and surface polishing quality of PUP-PEP. This technique combines the high current density and material removal rate of the electrolytic polishing mode with the superior surface polishing quality of PEP through voltage waveform modulation. For an Inconel-718 superalloy part fabricated by WEDM, PUP-PEP reduced surface roughness from Ra 7.39 μm to Ra 0.27 μm in 6 min under optimal conditions. The roughness decreased from Ra 7.39 μm to Ra 0.78 μm in the first 3 min under pulsed unipolar-polarisation voltage, resulting in a remarkable 233% increase in efficiency compared to that with conventional PEP. Subsequently, the voltage output voltage is transformed into a constant voltage mode, and PEP is continued based on PUP-PEP to finally reduce the workpiece surface roughness value to Ra 0.27 μm. The proposed PUP-PEP technology marks the implementation of ‘polishing’ instead of conventional rough-finish machining processes, presenting a new approach to the surface post-processing of metal near-net fabrication technologies.

Superior high-temperature strength of a carbide-reinforced high-entropy alloy with ultrafine eutectoid structure

Refractory alloys with high-temperature softening resistance are crucial for extreme high-temperature components in aerospace and weapon equipment. Traditional alloys and single-phase refractory high-entropy alloys suffer from unstable microstructures and loss of strength at high temperatures. Here we report a strategy to obtain a superior strong high-entropy alloy by introducing carbides to form micro-nano scale eutectic and eutectoid structures. These metal-carbide interfaces remain stable under high-temperature deformation and exhibit strong dislocation blocking effects. The ultrafine eutectoid structure provides a primary strengthening effect due to its numerous enhanced phase interfaces. The resulting alloy achieves a high temperature yield strength of 1.17 GPa at 1473 K and 0.92 GPa at 1673 K. This work provides valuable insights for optimizing the high-temperature performance and microstructure design of high-temperature composites to further extend their potential applications in high-temperature areas.