Electromagnetic metamaterial is an artificial composite composed of periodic subwavelength microstructure, which has a strong conduction regulation or absorption effect on electromagnetic wave, and it has been widely studied in the field of stealth design of aviation weapons and equipment. In this paper, the concept of electromagnetic metamaterial is introduced firstly, and the latest research progresses of electromagnetic control metamaterial, electromagnetic absorbing metamaterial, active tunable metamaterial and intelligent metamaterial are reviewed. Then, the stealth mechanism and the application research status of electromagnetic deflection metamaterial, electromagnetic absorbing metamaterial and frequency selective metamaterial are introduced. It is analyzed that the rich stealth mechanism and the strong designability are the main advantages of electromagnetic metamaterials as distinct from the traditional absorbing materials. For the development of electromagnetic metamaterial, this paper puts forward three suggestions from expanding the absorbing spectrum, enhancing the absorbing performance, and smart tunable of absorbing ability, specifically including the expansion of absorbing spectrum to infrared, laser and ultraviolet band, further improving the broadband absorbing ability, and intelligent adjusting the absorbing frequency band.

The United States General Electric Company (referred to as GE) has conducted research on SiC_f/SiC composite materials since the 1980s. The successful application and commercialization of GE’s SiC_f/SiC composites in engine systems were achieved after 30 years of continuous investment (nearly 1.5 billion USD) and the collaborative efforts of hundreds of scientists and engineers. This paper details the spiral development history of GE’s prepreg-melt infiltration (MI) SiC_f/SiC composites, focusing on their innovative applications in hot-section components for gas turbines and aero-engines. Through case studies of several critical hot-section components, GE’s research paradigm of “demand traction, technology verification, and engineering iteration”is elucidated. Furthermore, the 10-year progressive design iteration path of the 7FA engine turbine shroud is systematically analyzed, revealing the synergistic optimization logic between service failure feedback and forward design validation. In light of international advancements, this paper interprets GE’s establishment of a“material-process-test”technological barrier through vertical supply chain integration, digital twin-driven process optimization, and machine-learning-based inspection systems. GE’s experience demonstrates that technological breakthroughs require a balance between long-term fundamental research and agile engineering iteration. For domestic development, a closed-loop“design-manufacturing-assessment”research and development process should be established, guided by critical components, alongside multidisciplinary collaboration mechanisms. Additionally, China should strengthen foundational capabilities by leveraging universities and national research and development centers for mechanistic studies, implement multi-dimensional optimization under thermo-mechanical-chemical coupling constraints, accelerate industrial ecosystem construction, integrate fragmented resources, and build rapid“industry-academia-research”verification platforms. A digital transformation strategy encompassing full-chain data acquisition and AI integration is also essential. Finally, by synthesizing successful international practices and adapting them to China’s context, an autonomous development roadmap covering“basic research, pilot verification, standard formulation, and industrial synergy”is proposed, providing methodological guidance for advancing ceramic matrix composite technologies in high-thrust-to-weight-ratio aero-engine applications.

The development of next generation aero-engines requires support of advanced materials and appropriate new structures and technologies. According to the service environment of aero-materials,some points of view on combining the structure concept with material concept,the advancement and reliability of aero-engines with the controllability and safety of structure and defect for research and development of materials are proposed. From the aspects of fundamental properties of maximam service temperature,high temperature specific strength,antioxidation,toughness,conductivity and processing ability,the behaviour of traditional and new materials systems is analysed and some suggesstions aimed at the problems in development of aero-engine materials in China are presented.

The advanced polymer composites community has made great progress during the past thirty years.An assesment on the state of the art of the advanced polymer composites as well as their applications in aviation industrial is presented.The future development and research prospects of advanced polymer composites are discussed.

This paper introduced the two main electrica1 conduction mechanisms of the silicone conductive rubber,which are conductive pathway theory and quantum mechanics tunne1ing effect theory.The progress of electrical1y conductive fillers is mentioned,and the factors affecting the conductive properties of silicone rubber are discussed based on temperature,pressure,machining technics and so on.In addition,the applications and prospect of the conductive silicone rubber are briefly viewed.

Thermoplastic composites exhibit high toughness and damage tolerance, as well as good impact resistance. Additive manufacturing offers an effective way for making high-performance complex thermoplastic composite components without molds, which has a broad application prospect in aerospace and other fields. This article introduces the research progress of additive manufacturing process of short-cut fibers/continuous fibers reinforced thermoplastic composites. The processes and mechanical properties of different resins and fibers are compared. For the additive manufactured PEEK reinforced with 10%(volume fraction, the same below) of shortcut carbon fibers, the tensile strength and modulus can reach 109 MPa and 7.4 GPa, respectively, which is 85% higher than the pure PEEK. For the additive manufactured ABS reinforced with 10% continuous carbon fibers, the tensile strength and modulus can reach 147 MPa and 4.185 GPa, respectively, which is 5 times and 2 times of pure ABS. According to different processing routes and material systems, the equipment for fabricating advanced thermoplastic composites becomes larger and more integrated. Finally, from the material, equipment, process and application perspectives, the challenges and opportunities of thermoplastic composites by additive manufacture are identified.

High-entropy alloys（HEAs）have attracted considerable attention from the research community as a pioneering alloy design paradigm over the past two decades. They have fundamentally challenged traditional design paradigms and exhibited exceptional mechanical properties and functional characteristics, thereby positioning themselves as promising candidates for significant engineering applications in the future. Recent advancements have unveiled several alloy systems that demonstrate exceptional performance across diverse metrics, including low-temperature fracture toughness, high-temperature strength, impact resistance, radiation tolerance, and fatigue resistance. These qualities render HEAs highly attractive materials for research with substantial application potential in critical domains such as deep space exploration, deep-sea investigations, low-temperature superconductivity, and advanced nuclear energy technologies. This paper will briefly introduce the concept and classification of HEAs, and review the experimental progress of HEAs under various extreme conditions such as extremely low temperatures, high-speed impacts, and high nuclear radiation. We also summarize the strategies for enhancing the strength and toughness of HEAs, and extract the deformation mechanisms and physical and chemical properties of HEAs under different extreme loads. It is foreseeable that the main development direction of HEAs will be to form microscopic fluctuations in chemical composition and construct multi-scalestructural ordering efficiently through fine adjustment of the selection and proportion of alloying elements and optimization of heat treatment processes. For comprehensive studies on HEAs subjected to extreme loads, it is essential to explore their microscopic deformation mechanisms further while proposing innovative strategies designed to address inherent trade-offs between strength and toughness. The integration of state-of-the-art simulation techniques combined with advanced characterization methods will be crucial for improving research efficiency while providing insights into microstructural behavior. Additionally, tailored optimization approaches should be implemented for distinct advantageous systems and phase structures, particularly those capable of activating dislocation movements, twinning, phase transformations and incorporating novel processing methodologies such as additive manufacturing. Finally, conducting more realistic simulation experiments that closely replicate extreme environments along with generating relevant engineering data are vital steps toward accelerating the practical application of HEAs in challenging settings.

The basic failure modes in unidirectional composite laminates have been given and the damage characteristics in multi directional composite laminates have been summarized. In composite laminates there are four basic failure modes: matrix cracking, delamination, fiber breakage and debonding. Although numerous and complicated failure modes can be combined from the four basic failure modes mentioned above, all the failures in composite laminates can be divided into two kinds:"fiber dominated modes" and "matrix dominated modes". The failure analysis methods for composite laminates have been also discussed in this paper. At present, the knowledge of fractography of composite materials is growing and paid much attention.

A review on the 20th century development history of casting superalloys is presented.Several main events,vacuum melting,directionally solidified and single crystal superalloy,alloy design,Ni3Al-based casting alloys,numerical simulation technique and fine grain casting are described.Furthermore,some prospects on the developments of cast superalloy in the 21th century are proposed.

The strengthening mechanisms and strength prediction have always been the focus of investigation, because these are critical to the design of metal matrix composites (MMCs). Numerous strengthening mechanism and theoretical models have been developed to correlate the mechanical behaviors of MMCs with their microstructure characteristics, but no one accords with the experimental results very well. An overview of recent studies on strengthening mechanisms and models for MMCs is presented. The disadvantages, appropriate research orientation are also discussed.

The measurement principles of indentation creep by depth sensing indentation were elucidated,and recent progresses in investigation on indentation creep were also introduced.The creep behavior of metallic materials such as Ta,Ni and Ni-based alloy,BaTiO3 and Ag/Co multilayers were measured by depth sensing indentation.The stress exponents and the corresponding creep mechanism were also analyzed.

Pt/Ir thin film thermocouples were prepared on the surface of the GH5188 special-shaped high temperature superalloy, and the thin film thermocouples were placed on the flame flow table to test the transient temperature of the surface of the special-shaped high temperature superalloy. After four cycles of high temperature and high-speed flame burning, the total test time reached 8700 s, the Pt/Ir thin film thermocouple can still obtain stable temperature data. The success of this test indicated that Pt/Ir thin film thermocouples have taken an important step towards engineering application. Aiming at the engineering application of thin film thermocouples, the project team investigated the thin film preparation technology, interface control, integrated preparation, signal and system, etc., broke through 13 key technologies, and realized the engineering application of Pt/Ir thin film thermocouples. The breakthrough of this experiment makes China have the ability of temperature measurement under the condition of blade simulation service.

The fatigue life experiments of 7075-T651 aluminum alloy were conducted under different stress amplitude and S-N curves was gained from fitting the experimental data.An estimation of detailed fatigue limit result was 223MPa.The fractography of high stress amplitude and low stress amplitude using scanning microscope displayed that the crack initiation mostly derived from the interior flaw or inclusion,and crack propagation gone with the quasi-cleavage crack.The crack propagation regions under high stress amplitude was characterized by furrow and tyre patterns while lots of fatigue fringe together with the fatigue sidestep and secondary crack generated in the crack propagation regions of low stress amplitude.The tearing edge and equiaxial dimples existed in fatigue failure region of both high stress amplitude and low stress amplitude fracture surface.The bulky inclusion particles can be the crack initiation while dispersion of tiny precipitated phase has a positive influence on fatigue performance of 7075-T651 aluminum alloy.

P/M superalloy becomes excellent material for fabricating turbine discs used for advanced aviation enging due to its special structure and properties.To advance the applicable property and security of aviation enging,the material from melting original alloy to engineering application of turbine disc was studied,and remarkable results in aspect of so many key technologies were gained due to the result of the foundation of fabricating technique for turbine disc and the establishment of process and testing documents.Numerical simulation is widely used to fabricate P/M turbine disc for the purpose of shortening studying period and optimizing processes,and the preparatory experimental results were achieved.

The operating temperatures of hot-section components in advanced aero-engines continue to increase, accompanied by increasingly severe service conditions. Conventional thermal barrier coatings（TBCs）can no longer meet these demanding requirements, necessitating the development of new TBCs with higher temperature resistance and superior overall performance. This paper systematically analyzes the application requirements for new thermal barrier coating materials in advanced aero-engines, focusing on material composition, fabrication processes and microstructure. It elaborates on recent research progress in three types of novel TBCs: rare-earth-doped ZrO₂ coatings applied via atmospheric plasma spraying（APS）, rare-earth zirconate coatings produced by electron beam physical vapor deposition（EB-PVD）, and high-entropy ceramic coatings fabricated through plasma spray-physical vapor deposition （PS-PVD）. Compared to traditional double-layer structured yttria-stabilized zirconia（YSZ） TBCs, these new coating systems—based on rare-earth-doped ZrO₂, rare-earth zirconates, or high-entropy ceramics—exhibit lower thermal conductivity, enhanced thermal shock resistance, and superior resistance to calcium-magnesium-alumino-silicate （CMAS） corrosion. Through in-depth integration with processes such as APS, EB-PVD and PS-PVD, the performance of these coatings has been significantly improved, making them suitable for application in critical hot-section components like floating wall tiles and turbine blades. As breakthroughs continue to emerge in new materials, structures and processes, these advanced thermal barrier coatings are poised to provide crucial support for next-generation aero-engines, enabling them to surpass current temperature limits and achieve greater efficiency and reliability.

The microstructures and tensile properties of cold-rolled and T3 treated 2524 aluminum alloy sheet with the thickness of 2mm at different orientation were investigated by tensile test,OM,XRD and TEM analysis.On the basis of the model that regards the sheet containing only {110}texture,the relationship of in-plane anisotropy and the anisotropy of crystallography was analyzed.The results show that the strength of 2524 cold-rolled and T3 sheet orientated 45° and 60° with respect to the rolling direction is lower than that of specimens orientated 0°,30° and 90° with respect to the rolling direction.The elongation of the sheet orientated 45° with respect to the rolling direction is highest,And then the tensile properties of the sheet orientated 0° with respect to the rolling direction are both higher than that of the sheet orientated 90° with respect to the rolling direction.The IPA of cold-rolling condition alloy sheet is higher than that of T3 condition.The major crystallographic texture of 2524 cold-rolled sheet is {110},and the secondary crystallographic texture is {311}.But the major crystallographic texture of 2524-T3 condition is {110}.The in-plane anisotropy of mechanical properties of 2524 aluminum alloy sheet is closely related to the grain structure and crystallography orientation,among them crystallographic texture is responsible for the in-plane anisotropy of mechanical properties.

Benzocyclobutene is a thermally activated precursor to the highly reactive intermediate orthoquinodimethane. The intermediate will react either with itself or dienophile in a Diels-Alder fashion. The chemical reaction principle for benzocyclobutene compounds, the properties and applications of polymers from benzocyclobutenes are reviewed in this paper. The tendency and prospect for the development of the materials are also discussed.

Continuous fiber reinforced silicon carbide ceramic matrix composites were developing towards possessing self-healing properties for the need of high thrust mass ratio aerospace-engine working in thermal oxidizing environment.The microstructure and properties of a self-healing silicon carbide matrix composite were introduced.The mechanism of toughness and stiffness of the composite and the self-healing behaviors were commented.The application progress of self-healing silicon carbide component was summarized.Manufacturing method and technique feature were reviewed.Multi-component and multi-layer microstructure was the key point for this composite possessing self-healing and toughing properties,and oxidation resistant system which exhausted O2 and sealed crack in each layer.This self-healing silicon carbide matrix composite coule not only meet the requirements of for aerospace-engine service but decreased weight remarkably,increased thrust-weight ratio in return.

Aluminum-lithium alloys have formed a perfect material system with high specific strength, high toughness and high damage tolerance resistance after the development of three generations. It is attractive to replace the traditional aluminum alloys owing to their excellent weight reduction ability. It is considered as the ideal structural materials for the aircraft and warship in the 21^st century. This paper briefly reviews the development of Al-Li alloys, and introduces the idea of composition design, manufacturing and advanced application technology of the Al-Li alloys. It is pointed out that the high cost is the main problem restricting the further large-scale application of Al-Li alloys. The research directions, like to improve the product types of Al-Li alloys, develop anti-fatigue, anti-damage and low density Al-Li alloys, study the overall manufacturing technology of Al-Li alloy large parts, develop the Al-Li alloy aging forming technology, laser welding, friction stir welding and other advanced joining technologies, and other applications are also proposed in this paper.

The recent development of near net-shape investment casting technology for superalloys was introduced.The researching results of investment casting technology for superalloy turbine blades/vanes,integral turbine wheels,nozzle assembly and casings of aero engine in BIAM were mainly introduced.Meanwhile the researching scopes in the future was discussed.

Residual stresses of a very significant level were introduced when aluminum alloy parts were quenched in cold water from the temperature of solution treatment Residual stresses cause not only distortion and cracking, but also enhance susceptibility to stress corrosion cracking (SCC) and lead to premature failure The aim of this research is how to control and relieve residual stresses in high-strength aluminum alloy parts First, various quenching processes have been evaluated in an attempt to combine low residual stresses with the required levels of mechanical properties during solid solution, involving quenching into boiling water, spray quenching and polymer glycol quenchants The second part of this paper is focused on the comparison of different stress-relieving techniques, highlighting their key attributes, specific advantages and limitations Moreover, the paper concludes that all stress-relieving techniques should be carried out immediately after being quenched in the solution treatment.

A new type Korex honeycomb cell materials was introduced. Korex is an aramid/phenolic high mo dulus,high strength true composite honeycomb core. It was first introduced in 1992 in response to industry desires for a lightweight composite core with greater stiffness, strength and fatigue resistance. The mechanical properties and typical application properties for Korex honeycomb core of different cell-density have been also compared in the article. A few new type honeycomb structure have been given. The research for new type honeycomb cell structure and materials will efficiently increase the mechanical properties of honeycomb structure, decrease their structure weight and enhance their working reliability. All these are very beneficial to enlarge the application of honeycomb structure in aerospace and other industry fields.

The current research status of refractory high-entropy alloys（RHEAs） is reviewed, the composition design of RHEAs is described, and the effects of metal elements and non-metal elements on the structure and properties of RHEAs are summarized. In addition, the microstructure and mechanical properties of RHEAs under different preparation methods are described, and the strengthening mechanism of RHEAs matrix composites is discussed. The future development of RHEAs is prospected, and the following suggestions are put forward for its future research direction: enhancing of RHEAs by multiphase synergistic effects through the interface design between different phases; designing and optimizing the composition of RHEAs to develop RHEAs that are easy to process at room temperature; quickly screening the composition and microstructure of RHEAs by combining with high-throughput calculation methods; regulating and controlling the microstructure and structure of RHEAs by additive manufacturing technology; carrying out the configuration design of RHEAs matrix composites to balance the strength and plasticity of RHEAs matrix composites.

The current status of development of high performance aeronautical gear steel has been evaluated.Three generation gear steels,including high hardness steel used at conventional temperature,high hardness steel used at medium temperature and the steel which possesses ultra high hardness in case,ultrahigh strength with excellent toughness in core,corrosion resistance used at high temperature have been developed.It is the best way to obtain high power density and long life gear to develop higher-performance gear steel, superpure melted and advanced relative technique,such as design,manufacture,heat treatment of gear.

As a critical strategic material for aero-engines and industrial gas turbines, the composition/process design, optimization and process control of superalloys remain at the core of industry concerns. The present work focuses on addressing practical challenges in the development and production of superalloys and their components. It identifies key influencing factors in typical processes within the manufacturing workflow and employs a combination of advanced characterization techniques such as synchrotron radiation and high-throughput experimental methods. This integrated approach enables the design and optimization of critical process parameters for superalloy manufacturing, thereby providing foundational support for enhancing process technology, product performance, research and development efficiency, and reducing costs. Taking representative manufacturing processes involving liquid-solid and solid-solid phase transformations as examples, we explore precision tailoring strategies and validation methods for key stages including master alloy melting/remelting, synergistic particle size/morphology control in gas atomization, shrinkage porosity control during casting solidification, powder storage/desorption treatments, powder consolidation through hot isostatic pressing（HIP） and heat treatment procedures. In addition, optimal usage conditions are investigated for auxiliary materials or consumables integral to superalloy production, particularly ceramics, isothermal forging dies and brazing repair materials. Notably, the research on process tailoring reveals significant phenomena: （1）the impact of oxygen existence forms in cast and powder metallurgy alloys; （2）the influence of the initial microstructural state of alloys on the phase transformation temperature during HIP consolidation and heat treatment; （3）the formation and control of abnormal phases and defects in cast, powder metallurgy and additive manufacturing alloys, along with repair materials for brazing and ceramic refractories. The aforementioned findings establish a theoretical foundation for optimizing and tailoring superalloy process parameters and achieving precise manufacturing control, while also providing feasible technical pathways for industrial implementation.

To study the effect of spraying process parameters on the performance of Al₂O₃-SiC coatings, orthogonal tests are carried out to optimize the spraying process parameters, and the relationship between “spraying process- structure- bonding strength and thermal shock resistance” is established. The results show that the spraying power, powder feeding rate and spraying distance have no effect on the type of phases within the coating but significantly impact the coating quality and bonding strength. When the spraying power is 47 kW, the powder feeding rate is 30%, and the spraying distance is 110 mm, the coating bonding strength is the highest （10.51 MPa） and the porosity is the lowest（34.35%）. Thermal shock tests show that the coating does not fall off after 200 cycles at 900 ℃ and 1000 ℃, and the phases do not change. However, as the temperature is increased to 1100 ℃ and 1200 ℃, partial oxidative decomposition of SiC within the coating occurs, generating Si, C, SiO₂ and Al₆Si₂O₁₃, thus leading to coating peeling off due to the accumulation of thermal stress and the thickening of the thermally grown oxide (TGO) layer. The coating failure mechanism mainly originates from the thermal expansion coefficient mismatch between the ceramic layer and the bonding layer, the abnormal grain coarsening of the TGO layer, and the internal crack extension.

Titanium alloy is the main application material for the key components of aero-engine due to its excellent properties, such as light weight, high strength, high temperature resistance, and fatigue resistance. Because of its small elastic modulus, low thermal conductivity, and strong chemical affinity, it produces greater cutting force and higher cutting temperature in the machining process. Different thermal mechanical coupling effects can change the surface structure, composition, and mechanical properties of the material, resulting in different surface integrity state characteristics. This paper expounds the effects of process parameters, tool materials and properties, and lubrication methods on cutting force, cutting temperature, surface roughness and morphology, residual stress, microhardness, and microstructure based on the formation mechanism of surface integrity. It is pointed out that the existing researches mainly focus on the description of phenomena and laws. The research on the formation mechanism of surface integrity based on the thermal-mechanical coupling on the processing interface is lack, and the qualitative characterization system of surface integrity is not perfect. Therefore, the object of titanium alloy machining needs to be upgraded from test block to component, and the influence of the change of contact state of the processing interface caused by the time-varying machining trajectory on the surface integrity should be considered. Moreover, the quantitative evaluation of plastic deformation and grain characteristics is completed to accurately predict the gradient distribution of surface integrity. Taking fatigue performance as the goal, the surface integrity distribution meeting the service performance of components is deduced and designed, and then the processing conditions meeting the requirements are determined to realize the surface integrity processing.

This paper reviewed the progress of high-temperature PMR type polyimide matrix composites, and summarized its application in aeronautical engine field.

Graphene/Al composites have the characteristics of high strengthening efficiency, synergistic improvement of strong plasticity, and excellent comprehensive performance, which is expected to break through the bottleneck problem of poor strength- plasticity matching of metal matrix composites. However, the dispersion of graphene is an important issue that plagues the preparation of materials. The flaky powder metallurgy technology based on the mechanical ball-milling process can transform the spherical aluminum powder into flakes and realize the uniform dispersion of graphene. In this study, the mechanical ball-milling process was controlled by adding a process control agent (polydimethylsiloxane, PDMS) to prepare flaky Al powder, combined with pressure infiltration technology to prepare 0.6%(mass fraction) GNPs/6061Al composites. The results show that the diameter of flaky aluminum powder increases first and then stabilizes with the prolongation of milling time. As the viscosity of process control agent increases, the diameter of flaky aluminum powder is increased, and the flaky effect of aluminum powder is more obvious. At the same time, the viscosity of graphene defect content decreases first and then increases. Moreover, it is revealed that the graphene defects show a decreasing and increasing change pattern as the viscosity increased. Combined with the structure characterization and mechanical property test, the relationship between properties and structure is discussed, which has provided a reference for the subsequent preparation of graphene/Al composites.

The recent advancement of the oxidation protective coatings of C/C composites in China was reviewed.New technologies and new improvements of the traditional coating preparation technologies for C/C composites were introduced.According to the application conditions of C/C composites,the development trend of anti-oxidation coatings was also proposed.It was showed that the present research results could not meet the requirements of the coated C/C composites in severe work environments.The further researches would be focused on the preparation of suitable coating that could protect C/C composites from oxidation from room temperature to 1700℃ in high speed gas-fired environments.To reduce the cost of preparation,the coating that could works at 1800℃ for long time should be exploited.

Hafnium and zirconium can promote the formation of (γ+γ′) eutectic,MC(2) carbides,M2SC sulfides and Ni5M phases in superalloys,change script MC and M3B2 into blocky shape and delay the initiation and propagation of cracks by cleaning the free state sulfur at grain boundary and interdendritic regions and strengthening their cohesion.Both of elements Hf and Zr increase the stress rupture strength and ductility of cast superalloys at intermediate temperature and also improve the tensile strength and ductility at room temperature.Hf and Zr strict the precipitation of secondary carbides,such as M23C6 and M6C,therefore stabilize the microstructure of alloys during long-term exposure at elevated temperature.However,Hf and Zr lower the incipient melting temperature of superalloys.The melting of Ni5Hf or Ni5Zr phases may be considered as one of the main factors affecting incipient melting.By means of a pretreatment at 1150℃/8h,Ni5Hf phase can be eliminated in two ways: The reaction Ni5Hf+ γ(C) →MC(2)+ γ or solid solution.Hafnium may narrow down the range between temperature lost the interdendritic capillary feeding action and solidus,as well as may decrease the liquid content necessary for linking the interdendritic pools in the late solidification.The Hf-rich melts in interdendritic zone have superior fluidity,wettability and skin effect.These are the factors in increasing castability and weldability of Hf-containing superalloys and in decreasing tendency of hot tear.The high chemical activity of skin Hf-rich liquid promotes the formation of a thin layer of Hf2O on the surface of castings.Hf and Zr are the melting point depressant in the interlayer alloys used for brazing.It may be considered that dendrites formed in the early solidification are brazed by interdendritic Hfor Zr-rich melts.Eventually,the Ni-18.6Co-4.5Cr-4.7W-25.6Hf and Ni-10Co-8Cr-4W-13Zr alloys were developed according to the composition of Hf-or Zr-rich melts,and the Si-or B-free-bonding for single crystal superalloys could be realized.Studying the Hf-rich melts also leads to the development of unidirectionally solidified lamellar Ni3Al/Ni7Hf2 eutectic.The suitable compositions for these eutectic in situ composites are Ni-5.8Al-32Hf and Ni-4Al-26Hf-8Cr-4W.The results showed that the lamellar Ni3Al/Ni7Hf2 eutectic aligned parallel to the direction of solidification were prepared with temparature gradient G=250℃·cm-1 and solidification rate R=5μm·s-1 for the ternary alloy,and G=350℃·cm-1 and R=1μm·s1 for multicomponent alloy.

The cure reaction of cyanate ester resins via the auto-catalytic mechanism, or catalyzed by active-hydrogen compounds and by organic-metal complexes, as well as the different kinds of catalyst used were reviewed. The recent progress of catalyst research in photoinitiating organometallic complexes and organic tin compound is also discussed.

The article mainly shows the properties of silicone rubber at high or low temperature.The effects of metal oxides Fe2O3,Fe2O3/SnO2,SnO2,CeO2 on the thermal stability of methyl-vinyl silicone rubber(VMQ),methyl-phenyl-vinyl silicone rubber(PVMQ),and trifluoropropyl contained silicone rubber(FVMQ) were studied by heat aging test.Through coefficient of cold-resistance under compression and DMTA,the characters in low temperature of VMQ,PVMQ and FVMQ were also studied.Result shows that metal oxides such as Fe2O3,Fe2O3/SnO2,SnO2 and CeO2 can greatly improve the thermal stability of silicon rubber.The analysis of x-ray photoelectron spectroscopy(XPS) showed that Sn+4 were reduced to Sn0 in silicone rubber during thermal air aging.The thermal stability of silicone rubber could be improved by some metal oxide.The results of DMTA showed that the rubber based on PVMQ,SKTFT-50,SKTFT-25 and the copolymer have excellent cold resistance.

The TLP bonding process for DD3 superalloy using a B-contain interlayer alloy with different temperature and holdingtime is analyzed. Microstructures of different joints were observed and the widths of the eutectic zone of the centre of the joints were measured. It shows that the width is inversely proportional to the square root of holding time. Based on the result, the time for isothermalsolidification at 1150℃, 1200℃ and 1250℃ are not more than 3h, 2h and 1h respectively by the estimation. By establishing the diffusion model and using the error function solution to the second Ficks law,the time for isothermalsolidification at different temperature is calculated by NiB phasediagram and DD3B analogous phasediagram,respectively.The calculated results show that for a certain bonding system, there exists an optimum temperature at which the time for isothermal solidification is the shortest. According to the experimental results, it is suitabk to choose 1250℃ as the bonding tamperatune for DD3 superalloy.

An experimental study of stable fatigue crack propagation behavior and the measurement of fatigue crack propagation thresholds of YB-MD-3 PMMA plates was carried out at room temperature.During the preparation of initial through fatigue cracks for M(T)specimens,load cycles with compressive portion demonstrates better quality than usual tension-tension loading.The fatigue crack propagation rate in Paris's region for certain load ratio shows good correlation with a straight line in double logarithmic da/dV-ΔK coordinate.The da/dN and the slope of the straight line increases with the increase of load ratio.For the negative load ratios,however,the compressive portion in load cycles accelerates the crack growth.A proper formulation to these effects is unavailable.The fatigue crack propagation rate in YB-MD-3 plates is also sensitive to the change of load frequency at room temperature,even for very low frequencies,say,1Hz and 2Hz.

High-temperature resistant ceramic matrix composites (HT-CMCs) have demonstrated immense application potential in aerospace, energy, and other extreme service environments, thanks to their outstanding attributes such as exceptional high-temperature resistance, high strength, low density, and excellent chemical stability. Traditional manufacturing processes are constrained in fabricating HT-CMCs with complex shapes and high performance. In contrast, additive manufacturing (AM) technology has paved a new way for the production of HT-CMCs with intricate structures, leveraging its unique capability of layer-by-layer construction. This technology substantially improves the functional properties and structural efficiency of materials by enabling the direct fabrication of complex internal features, like cooling channels. It also supports performance-oriented precise control and customized production according to specific service requirements, while significantly reducing material waste and effectively cutting down manufacturing costs. This paper focuses on the additive manufacturing technology of HT-CMCs. It introduces the technical principles and current application status of this technology, and places particular emphasis on expounding the latest research advancements both domestically and internationally in material system design, forming technologies, and process optimization for additively manufactured HT-CMCs. Furthermore, this paper sets out the future trends of additive manufacturing for HT-CMCs. In terms of material-process synergy, the focus is on overcoming the bottleneck of interface bonding in multi-material printing and developing composite processes to achieve multi-functional integration and gradient structures. Regarding the construction of intelligent systems, the aim is to establish a “digital control-real-time monitoring-parameter optimization” system and reduce trial-and-error costs through AI-based parameter adjustment. In the realm of modularization and circular manufacturing, the emphasis is on developing interchangeable standardized modules and innovating ceramic waste recycling technologies to enhance material utilization rates. All these endeavors are aimed at promoting its engineering application in cutting-edge fields.

Damage detection is a critical link of aviation equipment development, field operation and maintenance, which directly affects the development process and service safety of aircraft structure. In recent years, domestic and foreign scholars and scientific research institutions have carried out a lot of research works in the field of ultrasonic nondestructive testing. Based on this, this paper, guided by the needs of damage detection in the development and operation of aviation equipment, briefly analyzes the characteristics and requirements of typical structural damage of aviation equipment and in-situ detection. This paper focuses on summarizing the latest research progress of ultrasonic theories and methods, advanced detection sensor designs and special detection device research and development. Furthermore, incorporating new issues, ideas and directions emerging from technological research and engineering practice, this paper summarizes and forecasts the main challenges and future development trends in areas such as damage detection technologies for heterogeneous materials, transducer design methods for complex-shaped structures, and the equipment research and development and engineering application of new non-contact testing devices.

The corrosion and protection for aeronautical materials in China is reviewed.The techniques and research in natural environmental test,indoor accelerated tests,corrosion mechanics and tests,high temperature protective caotings,surface treatment and protective techniques are introduced.The development trend and application prospect of corrosion and protection are proposed.

A series of polyimides had been prepared via one-step high temperature polycondensation procedure from 1,4-bis(3'-amino-5'-trifluoromethylphenoxy) biphenyl(m-TFDAB) and 3,3',4,4,'-biphenyltetracarboxylic dianhydride(s-BPDA) or 2,3,3',4'-biphenyltetracarboxylic dianhydride(a-BPDA),respectively.Two polyimides,PI-1(s-BPDA/m-TFDAB) and PI-2(a-BPDA/m-TFDAB) have been successfully prepared by one-step procedure,whose properties were widely researched.The results showed that asymmetry wouldn't greatly affect the thermal and mechanical properties of the polyimides.On the contrary,asymmetry enhanced the solubility of the polyimides in organic solvents and increased the transparency of the PI film.PI-2 was soluble not only in polar aprotic solvents,but in many common solvents.PI-2 film showed good transparency in the visible light region with transmittance of 86% at 450nm wavelength.Furthermore,PI-2 exhibited good thermal stability with the initial thermal decomposition temperature of higher than 580℃ in nitrogen and 67% of residual weight ratio at 700℃.

The appearance of element Zr in aluminum alloys was summarized in the paper. Effects of the element on aluminium alloys such as recrystallization behaviour, quench sensitivity, aging behaviour and comprehensive properties (tensile strength, fracture toughness and stress-corrosion resistance etc.) were emphasized on. Applications of element Zr in aluminum alloys, especially in high-strength aluminum alloys were briefly introduced. Based on the new tendency of current research and development, it was pointed out that the understanding and investigation of element Zr should be made much further.