Diamond-reinforced metal matrix composites, which exhibit unique properties of both metals and diamonds, are used as functional and wear-resistant materials in various fields. Additive manufacturing technology provides a novel approach for fabricating complex components of metal/diamond composites, significantly enhancing the design versatility of components. Based on several key additive manufacturing techniques, including selective laser melting, laser cladding and cold spraying, this paper introduces the research progress in the additive manufacturing of metal/diamond composites. It covers powder raw materials, core processing technologies and practical applications. Emphasis is placed on discussing the causes, consequenses and potential solutions for sputtering and diamond graphitization that may occur during the manufacturing process. Finally, the main challenges and future development directions of metal/diamond composites in additive manufacturing are summarized. The main manifestations are as follows: in the additive manufacturing process, problems such as diamond splashing, interface control between metal and diamond particles, graphitization of diamond and damage to diamond particles occur. The key issues to be addressed focus on optimizing the forming process to achieve coordinated control of the composite material’s density, interface bonding and diamond protection.

It provides theoretical guidance for the optimization of mechanical properties to research the dynamic shear mechanical properties and microstructural evolution law of laser-cladding Inconel 625（IN625） alloy. A series of dynamic shear experiments are conducted using the split Hopkinson pressure bar（SHPB）at varying ambient temperatures（20, 600, 800 ℃ and 1000 ℃）and strain rates（40000, 60000 s⁻¹ and 80000 s⁻¹）. These experiments aim to establish the dynamic shear stress-strain relationship. Pre- and post-loading morphologies and crystal structures of the alloy are characterized using scanning electron microscopy（SEM）and electron backscatter diffraction（EBSD）. The results show that both the strain rate strengthening effect and temperature softening effect are pronounced in laser-cladding IN625 alloy, with temperature softening effect predominantly influencing its mechanical behavior at elevated temperatures. Compared to the unloaded sample, the dynamic shear test at room temperature lead to the development of a prominent shear texture, with an increase in dislocation density and a decrease in average grain size. Specially, the proportion of small-angle grain boundaries increases from 29% to 85%. Conversely, high-temperature dynamic shear experiments, compared to room temperature loading, weaken the preferred orientation and reduce the dislocation density of the crystals. These high-temperature conditions further decrease the average grain size and lower the proportion of small-angle grain boundaries from 85% to 73.5%.

Light-curing 3D printing technology stands out as one of the oldest, fastest-growing and most widely used technologies in the field of 3D printing. This technology utilizes ultraviolet or other light sources to rapidly solidify liquid photosensitive polymers, creating products with complex geometrical structures that are difficult to achieve with traditional manufacturing methods. This paper summarizes the latest research progress in photocurable polymer materials for 3D printing, covering various types of photocurable polymers including thermoplastics with high remoldability, thermosets with good structural stability, and hydrogels with hygroscopic network cross-linking structures. Additionally, the applications of photocurable 3D printing polymers in various fields such as biomedical, flexible electronic devices, soft robotics, energy storage, and aerospace are discussed in detail. This review also explores the application of photocuring technology in 4D printing, highlighting the potential of 4D printing in dynamic materials and smart manufacturing. In the future, light-curing 3D printing technology is expected to advance toward the development of high-performance polymer composites, the integration of intelligent and automated printing systems, and the deep integration with cutting-edge technologies such as artificial intelligence, continually driving its applications and innovations in high-tech fields and advanced manufacturing.

The development of supersonic aircraft has created an urgent demand for heat-resistant aluminum alloy that can serve at the temperatures range from 300 ℃ to 500 ℃. However, the high-temperature mechanical properties of heat-resistant aluminum alloys are still unable to meet practical application requirements. Therefore, further research is needed from the aspects of material composition design and microstructure control to improve the comprehensive mechanical properties of heat-resistant aluminum alloys. In this paper, the research progress of heat-resistant aluminum alloys is reviewed from the aspects of microalloying design and eutectic alloys, and the development trend of heat-resistant aluminum alloys is prospected. The article first systematically introduces the development history and research status of Al-Sc, Al-Cu, Al-Si, and Al-Mg heat-resistant aluminum alloys, focusing on the microalloying design ideas of heat-resistant aluminum alloys, as well as the effects of transition metal elements and rare earth elements on precipitation phases, microstructure, and mechanical properties. Subsequently, the development status of heat-resistant eutectic aluminum alloys in Al-Fe, Al-Ni, Al-Ce, and Al-Si systems is comprehensively summarized, with a focus on the important role of rapid solidification technology and additive manufacturing technology in promoting the development of heat-resistant eutectic aluminum alloys. Finally, the main problems faced in the development and application of new heat-resistant aluminum alloys are analyzed, and the development trends of future research on heat-resistant aluminum alloy is discussed from the perspectives of data-driven composition design, high-throughput experimental verification, engineering application research, and standard system construction.

The three-layer structure molybdenum-silicon high-temperature oxidation-resistant coating was prepared on selective laser melting Ta10W alloy by slurry sintering process. The microstructure and element distribution of the Ta10W alloy and coating were characterized by SEM and EDS. The tensile properties, microhardness of the Ta10W alloy and coating, and the coating bonding strength were tested. The results show that the coating of selective laser melting Ta10W alloy is divided into three layers: outer, sub-outer and inner layers. The outer layer is TaSi₂ and MoSi₂ phases, the sub-outer layer is TaSi₂ phase and dispersed Ta₅Si₃ phase, and the inner layer is Ta₅Si₃ phase. The yield strength, tensile strength and uniform elongation of the coating and remove coating specimens are 639, 647 MPa, 13.6%, and 602 MPa, 675 MPa, 22.7%, respectively. Compared to the Ta10W alloy specimen, the uniform strain of the remove coating specimen is increased by 5.5%. The reason for this is that the thermal effect in the coating preparation process eliminates the residual stress of the Ta10W alloy formed by selective laser melting. The yield strength of the coated specimen is increased by 37 MPa due to the application of the coating. The microhardness of the outer layer, sub-outer layer, inner layer and Ta10W alloy were 550HV_0.2, 1120HV_0.2 , 534HV_0.01 and 307HV_0.2, respectively. The average coating bonding strength is 63 MPa, which is higher than that of the ceramic and high entropy alloy coatings. This is due to the fact that the three-layer coating has a good metallurgical bond to the Ta10W alloy.

The elliptic section body-centered tetragonal（E-BCT）lattice structure of 316L stainless steel fabricated based on selective laser melting（SLM）, represents an enhanced lattice structure with improved compressive performance. By optimizing the cross-sectional shape of the struts in the traditional body-centered tetragonal（BCT）lattice, the compressive properties of the lattice structure are significantly improved. Based on the mathematical model of the E-BCT lattice structure, the theoretical force model, and the Timoshenko beam theory, a relationship model is derived between structural parameters and relative density as well as effective elastic modulus. E-BCT lattice structures with varying semi-major axis lengths of the elliptical cross-section are fabricated using the SLM process, and static compression tests and finite element simulations are conducted. The study reveals that as the semi-major axis and shape factor of the elliptical cross-section increase, the performance of the E-BCT lattice structure improves significantly compared to the BCT lattice. The maximum improvement in effective elastic modulus is 637%, with average experimental and theoretical simulation errors of 6.5% and 5.1% respectively. The yield strength shows the maximum increase of 654%, with an average experimental and simulation error of 5.4%. Additionally, the specific stiffness and specific strength exhibit maximum improvements of 308% and 321% respectively.

The damage evolution and failure process of pre-corroded additive manufacturing AlSi10Mg through in-situ tensile experiments under an optical microscope and micro-scale digital image correlation（μ-DIC） were investigates . Combining the microscopic deformation field evolution, material microstructure, three-dimensional corrosion morphology and fracture microscopic morphology to analyze the initiation and propagation of micro-cracks in pre-corroded AlSi10Mg. The results show that the stress concentration around the corrosion pits and subsurface defects（caused by the additive manufacturing process） leads to the initiation of micro-cracks. There are multiple micro-cracks initiating at the same time, and the propagation and coalescence of micro-cracks originated from the key damage regions dominate the final failure of the specimen. Material micro-structure and corrosion morphology have an important influence on crack propagation.

Additive manufacturing provides a new way to develop high-performance superalloys and components. A γ′- strengthened CoNi-base superalloy suitable for additive manufacturing was developed, and a crack-free block material was prepared by optimizing the parameters of electron beam melting（EBM） technology. The experimental results show that the lowest porosity of the alloy is about 0.14% when the scanning speed is 2000 mm/s. The microstructures of the as-printed CoNi-base alloy are columnar grains growing along the <001> direction, the average grain width is about 235 μm, and the volume fraction of γ′ phase is about 30%. After hot isostatic pressing and solution aging treatment, the porosity of the alloy is further reduced to about 0.09% with unobvious change of columnar grains. The average size of γ′ phases is about （70±18）nm with the volume fraction of about （32±3.6）%. The results of room temperature tensile tests show that the additive manufactured γʹ-strengthened CoNi-base superalloy exhibits excellent strength and ductility, showing a good potential of industrial application.

Introducing emerging high entropy alloys materials into advanced intelligent manufacturing for laser additive repair is expected to promote the deep integration of new generation of materials and manufacturing technology and greatly improve the utilization of raw materials and energy, which have broad application fields and excellent development prospects. This paper introduces the application status of high entropy alloys in laser additive repair, and points out that the mismatch of strength and toughness, inaccurate performance control and unclear strengthening mechanism are the key scientific problems that need to be solved urgently in the expansion and application of high entropy alloys in laser additive repair. Exploring the ductile-brittle transition mechanism of the high entropy alloys cladding coating metal, clarifying the basic mapping relationship among the materials, processes, microstructure and coating performance of cladding coatings, obtaining a complete and effective method for predicting the composition of high entropy alloys, innovating the design of alloy powder system, optimizing and adjusting the control processes, and obtaining a high-performance cladding coating suitable for extreme service environment and with low cost are the main research focus and development trends in the future.

Selective laser melting（SLM）can achieve nearly net-shape complex parts of GH3536 alloy, and its high temperature mechanical properties are important indicators for safe service. The effect of heat treatment on microstructure and high temperature tensile properties of SLM GH3536 alloy were studied. The heat treatment at 1225 ℃ for 1 h was carried out to explore the regulation mechanism of microstructure and properties. The results show that heat treatment can effectively eliminate the cellular subgrain structure inside the grains, which significantly enhances the dislocation slip ability. The tensile elongations at room temperature, 650 ℃ and 815 ℃ are increased by 75%, 92% and 683%, respectively. In addition, the decrease of the aspect ratio of the columnar grains significantly reduces the anisotropy in the heat-treated sample. The fracture analysis shows that the fracture mode of the heat-treated sample changes from intergranular fracture to mixed fracture with the increase of tensile environment temperature.

Key components used in the high-pressure compressor of advanced aero engines operating in the 550-600 ℃ range have an urgent demand for 600 ℃ high-temperature titanium alloy. However, the use of casting, forging, and other traditional processing techniques is not sufficient to meet the requirements for gradient or composite structures, functional integration components and complex components that are difficult to form. Additive manufacturing is an advanced manufacturing technology that offers unique advantages such as material design-manufacturing integration and complex design-customization integration. It provides a new approach to the development of new materials and technologies of 600 ℃ high-temperature titanium alloy. Currently, attention is being paid to the processing of 600 ℃ high-temperature titanium alloy by using additive manufacturing techniques at home and abroad, focusing on the relationship among materials, processing, structures, and properties. Firstly, this paper reviews the research on 600 ℃ high-temperature titanium alloy in brief, introduces the microstructure characteristics of deposited and post-treated states of 600 ℃ high-temperature titanium alloy under different additive manufacturing processes, and analyzes key properties such as tensile properties, creep properties, thermal fatigue properties, and antioxidant properties. Then, the research progress of composite materials based on 600 ℃ high-temperature titanium alloy and gradient structure built by additive manufacturing is discussed. Finally, the prospects are provided for research directions including the development of 600 ℃ high-temperature titanium alloy materials for additive manufacturing, exploration of hybrid manufacturing processes, defect control, and establishment of performance evaluation standards.

K403 nickel-base superalloy is widely used in the manufacture of aero-engine turbine blades because of its excellent properties at room temperature and high temperature. In order to solve the problem of turbine blade crack defects caused by long-term service in complex working conditions, in this work, two different processes of （tungsten inert gas, TIG） welding and laser cladding were used to repair the blade cracks, and the microstructure and properties of the repaired region were studied. The influence of TIG welding and laser cladding repairing on microstructure, mechanical properties and failure behavior was analyzed. The results show that the microcracks tend to occur near the repair interface using the TIG welding repairing process, which are mainly caused by carbides and low melting point eutectic structure. The grain and structure of the repaired area by laser cladding repair technology are more uniform, and the microcrack defects can be easier to control. The comprehensive mechanical properties of the samples repaired by laser cladding are obviously higher than those repaired by TIG welding repairing process, and the samples repaired by laser cladding have better process stability. The tensile strengths of the samples using the laser cladding repair process and the TIG welding repair process at room temperature have reached 87.44% and 69.22% of the strength of K403 base material, respectively. According to the failure analysis results, the tensile fracture at room temperature in the repaired region presents mixed fracture characteristics, and the tensile fracture at high temperature presents intergranular fracture characteristics. Microcracks in the repaired area, local liquid phase deficiency defects and carbide structure are the main reasons of failure. The laser cladding technology has the advantages of heat source concentration and smaller heat affected zone, which can effectively restrain the defects and refine the microstructure. Therefore, the laser cladding repair process is used to repair the edge plate crack damage generated during the blade test run. After fluorescence and kerosene-chalk detection, the repairing process meets the relevant reuse requirements.

Multiple GH4169 samples were prepared with the regulation of the forming process of selective laser melting（SLM）, particularly in laser power and scanning speed. The microstructure including defect morphology and distribution was observed by using metallography. The sample porosity was acquired using X-ray computed tomography（XCT）, and the three-dimensional characteristics of defect were also statistically studied. The correlation of forming process and defect characteristics was finally analyzed. The results show that when the optimized energy input density is 59.1 J/mm³, the forming samples share common features of overlapping melting trace with a tidy morphology, randomly distributed pores with sizes of less than 30 μm and the density is as high as 99.9998%. Within a narrow window of forming process（220-300 W, 700-1300 mm/s）, the scanning speed takes more responsibility for the sample density, and its high value tends to form extremely irregular lack of fusions（LOFs） that distribute in the overlap of melting trace. As deviating from the optimized process, the number of defects has increased, and some defect sizes are also greater than 30 μm. The shapes of pores and LOFs respectively formed by high laser power or high scanning speed are closely related to their own sizes, that is, the larger the size, the more irregular the shape, which produces more detrimental effects than regular pores.

The effect of heat treatment on the microstructure and high temperature mechanical properties of SLM GH4169 alloy was studied by using a self-developed in-situ high temperature tensile device. The results show that the grain morphology of as-built alloy changes from columnar crystal to equiaxed crystal after homogenization+solid solution+aging treatment （HSA）, coupling with Laves phase dissolution, and a large amount of γ′ and γ″ strengthening phase precipitates. At 650 ℃, the yield strength and tensile strength of the as-built sample are 574 MPa and 740 MPa, while the yield strength and tensile strength of HSA sample are 818 MPa and 892 MPa respectively, which are 42.5% and 20.1% higher than that of the deposited alloy. The deformation process can be further characterized by in-situ tensile testing. The surface grain undulation of the as-built sample gets larger, the coordinated deformation ability becomes stronger, and the plastic flow ability gets better.The cracks in the as-built sample are originated around the Laves phase, spreading along the dendrite towards the maximum shear stress, and shear fracture occurs after necking of the sample. In HSA samples, the cracks are initiated around carbides and propagating along the grain boundaries. The fracture mode is a mixed type, involving both intergranular and transgranular fractures.

GH3536 and GH4169 nickel-based superalloys are widely used in aerospace engines and other hot-end components. In this paper, GH3536 and GH4169 alloy samples were fabricated by optimizing the process parameters using selective laser melting（SLM）, the defect characteristics and microstructure of two alloys, as well as the effects of different homogenization temperatures and holding times on microstructure evolution, average grain size, and properties of two alloys were studied. The defect characteristics and microstructure were investigated by OM, SEM, and EDS, et al. The Vickers hardness meter was used to test the alloy’s microhardness. The results indicate that the as-built GH3536 alloy exhibits more defects, including pores, cracks, and lack of fusion, while only pores are present in as-built GH4169 alloy. The melt pool of alloy is eliminated by homogenization treatment, and the grains grow into equiaxed grains. M₂₃C₆ are found to distribute within grain boundaries and grain interiors of GH3536 alloy, while NbC are found to distribute within grain boundaries and grain interiors of GH4169 alloy, and the amount of precipitates is significantly reduced with the increase of homogenization temperature. The average grain size of GH3536 alloy is increased by 106.8% from 48.5 μm at 1130 ℃/1 h to 100.9 μm at 1250 ℃/4 h. The grain size of GH4169 alloy is increased by 53.3% from 57 μm at 1080 ℃/1 h to 87.4 μm at 1200 ℃/4 h.The homogenization treatment of GH3536 alloy and GH4169 alloy results in a significant decrease in microhardness of the former, from 262HV to 180-190HV, while the latter shows a significant increase, from 313HV to 430-450HV.

The microstructure, tensile and damage tolerance properties in different directions of Al-Mg-Sc-Zr alloy fabricated through selective laser melting（SLM）have been investigated. The results show that the YZ plane is a bimodal grain morphology composed of fine equiaxed grains and coarse columnar grains, while the XY plane is composed of fine equiaxed grains. The yield strength and tensile strength in both 0° and 90° directions are over 500 MPa, and the anisotropy is small, while the elongation in 90° direction is significantly lower than the 0° direction due to the lack of fusion（LOF）defects between the deposited layers. The K_IC of the 0° and 90° CT samples are respectively 21.41 MPa·m^1/2 and 20.89 MPa·m^1/2. The resistance to crack propagation in columnar grains region is lower and leading to a smaller K_IC for 90° CT samples. The microstructure and defects are the two main factors that affect the anisotropy of crack propagation performance. The LOF defects play a leading role in the near-threshold regime, and the crack propagation rate is faster when the crack propagation plane is parallel to transverse direction. On the other hand, the microstructure plays a leading role in the steady-state propagation regime. The fracture surface exhibits transgranular fracture when the crack propagation plane is parallel to transverse direction, which provides higher crack propagation resistance and result in lower crack propagation rate.

In order to clarify the microstructure of Al-Mg-Sc high-strength aluminum alloy prepared by ultra-high speed laser melting deposition, and study the relationship between structure and properties, Al-Mg-Sc high-strength aluminum alloy was prepared by using 7075 aluminum alloy as matrix and self-developed equipment（LDF3000-40 laser melting deposition machine）. The effect of laser scanning rate on the microstructure and tensile properties of the materials was investigated. The results show that there are no obvious defects such as pores and cracks in the samples deposited by ultra-high speed laser melting, but contain a few small keyholes. The samples are composed of fine α-Al equiaxial crystals and dispersed Al₃（Sc, Zr）particles. The effect of scanning rate on mechanical properties is further studied by numerical simulation. It is found that the faster scanning rate of laser in the range of 0.1-1 m/s can reduce the accumulation of powder materials and porosity of the surface of the deposition layer, thus the mechanical properties can be improved. The maximum tensile strength is 303 MPa and elongation at break is 22.5%.

Nickel-based superalloys are important structural materials in turbine engines and gas turbines, but their conventional fabrication processes are complex, costly and have poor raw-material-utilization rate. The electron beam powder bed fusion（EBPBF） technology is a new solution for forming superalloys, which can realize near net forming of complex structural parts. During more than ten years of development, EBPBF technology has realized the high-quality formation of superalloy materials and components represented by Inconel 718 and Inconel 625, and has continuously extended its capability to form crack-free, high-γ'-phase-portion difficult-to-weld nickel-based superalloys, and can even directly prepare single-crystal nickel-based superalloy components. In this paper, the relevant literatures on EBPBF nickel-based superalloys in recent years are reviewed, and the current research status from the perspectives of printability, process optimization, property characterization of EBPBF nickel based superalloy components are analyzed and summarized, and also the future research work is proposed.

GH4169 alloy usually serves in high temperature environment, and the high temperature performance of GH4169 alloy made by additive material is often lower than that of the standard of forgings, which affects its service safety, thus it is necessary to improve its safety by means of heat treatment. In this work, GH4169 alloy was prepared by selective laser melting（SLM）, and the effects of hot isostatic heat treatment process on the microstructure, high temperature tensile properties and high temperature stress rupture properties of the SLM formed GH4169 alloy were investigated by using characterization methods such as optical microscopy（OM）, scanning electron microscopy（SEM）and X-ray energy dispersive spectrometry（EDS）, etc. The results show that, compared with the conventional heat treatment processes, the grains of GH4169 alloy after hot isostatic treatment are equiaxed, the pores and Laves phases are basically disappeared, the short rod-like δ phase is more continuous at the grain boundaries, a large number of granular γ'' phases are precipitated inside the grains, and the grains are significantly refined. After hot isostatic pressing treatment, the ultimate tensile strengths of GH4169 alloy at 650 ℃ are 1053 MPa and 1051 MPa, the elongations after breaking are 8.6% and 8.5%, the high temperature stress rupture properties are 1620 min and 2065 min, and the high temperature endurance time is improved by 90 times and 30 times respectively in scanning and building direction. The high temperature ultimate tensile strength and high temperature stress rupture properties are higher than wrought standard, while the elongation after breaking has not exceeded the wrought standard.

Nickel-based superalloy is an essential material to prepare hot-end components in aero-engines and gas turbines, due to its excellent mechanical properties under high temperature. Additive manufacturing（AM） is one of the most important techniques to fabricate superalloy components with complex geometry. In this paper, the research progress of microstructure and defects of AMed superalloy is reviewed. Based on the existing literature, tensile properties of GH3536, GH3625 and GH4169 are summarized. Typical applications of AMed superalloy components in aero-engines and gas turbines are presented. Finally, for the problems in existing investigations, it is suggested that the future research can focus on materials design, heat treatment/hot isostatic pressure process optimization, single crystal preparation, real-time monitoring technique development and internal surface treatment technique innovation.

Additive manufacturing is a new manufacturing technique that integrates laser, digitization, materials and other disciplines. It has the advantages of dimensionality reduction manufacturing, complex forming, and high material utilization. It is one of the most promising techniques in the field of material processing. Metal additive manufacturing technique has been widely studied and applied in the aviation field. The research on the additive manufacturing of aviation metal materials by domestic and foreign scholars continues to deepen. AECC Additive Manufacturing Technology Innovation Center has carried out a quantity of research and obtained some data from the four factors of metal additive manufacturing: microstructure, defects, surface and configuration. Some phenomena and laws have been found, including the characteristics and influencing factors of microstructure continuous growth; influence of the structure on mechanical properties; the characteristics and causes of common defects（pores, cracks, incomplete fusion） in additive manufactured typical materials and their influence mechanism on mechanical properties, especially fatigue properties; the relation between surface roughness and forming angles, and the influence of surface states on fatigue properties; factors influencing configuration of metal additive manufacturing. Finally, the problems existing in the development of metal additive manufacturing are summarized, and the suggestions for future research and development are put forward.

The application of metal additive manufacturing technology and products in the aviation field requires optimized structural design at macroscale and precise manufacture control at microscale. As one of the typical features of additive manufacture, microstructure inevitably affects the material performance. The research has shown that the uniformity, plasticity, and fatigue fracture characteristics of additive manufacturing materials are often inferior to traditional materials, while their strength, hardness, wear resistance, and some microscale properties are often better than traditional materials. The size effect in the micro/nano-scale and the heterogeneous characteristics of materials have a significant impact on metal materials with microstructures. Under different microstructures, materials can achieve a better balance between strength and ductility, which is also applicable to additively manufactured metals. Therefore, the process characteristics of additive manufacturing and the heterogeneities introduced by human design are both expected to significantly improve the comprehensive performance of metals, which have important guiding value for the application of metal additive manufacturing in the aviation field. However, since many of the mechanism of these phenomena are still unclear, the strength-ductility synergistic and antagonistic relationships with other properties of the materials are also worth further research.

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.

Direct solid diffusion bonding of Ti₂AlNb alloy was carried out, and the effect of pressure on the microstructure and mechanical properties of the bonded joints was studied. Scanning electron microscopy was used to analyze the microstructure of the welded joint under different pressures. The tensile property of the joints with different pressures was tested and the variation trend of the tensile property with pressure was analyzed. The results show that with the increase of pressure, the deformation within the sample surface layer increased, and the dynamic recovery and recrystallization occurred in the deformed area at high temperature, which promotes the closing of voids on the bonding interface and the rise of well-bonded areas. A diffusion bonded joint of Ti₂AlNb alloy can be divided into three parts: recrystallization zone, deformation zone and base metal. The recrystallization zone is mainly composed of equiaxed B2 phase and α₂ phase. With the increase of pressure, the width of the recrystallization zone becomes wider obviously, and the strength of the bonded joint increases first and then decreases. When the welding parameters are 960 ℃-60 MPa-120 min, the welded joint had the best performance, and its tensile strength is 972 MPa, reaching 98% of the base metal. An excessive pressure coarsened the recrystallization grains, and cracks appeared at the interface of the recrystallized zone and the deformation zone, which deteriorated the performance of the bonded joint.

In the current aviation industry, laser melting is an ideal technique for repairing and surface treatment of TC4 alloy parts, which has advantages over traditional metal repair techniques in terms of process. In this work, laser melting repair processes were performed on the surface of alloy specimens by different laser scanning speeds at a power of 2 kW, and the changes in metallographic organization, electrochemical corrosion properties and mechanical properties of the repaired surfaces were detected and analyzed. The results show that the significant microstructural changes are occurred during the laser repair process. The best corrosion resistance of the repaired surface is achieved at a laser scanning speed of 150 mm/min. The best microhardness and wear resistance of the repaired surface are achieved at 200 mm/min.

As the most representative additive manufacturing method in the field of aviation equipment at present, the laser additive manufacturing supports the structure design innovation, rapid development and verification. Among them, selective laser melting is mainly used for precision near net shape manufacturing of complex precise functional structures, and laser direct metal deposition is mainly used for manufacturing large and complex load-bearing structures. In order to support the strategic layout of the development of additive manufacturing technology in the aviation field, this paper sorts the current situation and development trend of laser additive manufacturing, and points out that the focus of additive manufacturing development is bound to turn to the metallurgical quality, mechanical properties and their stability control of products. The research and development of intelligent functions such as online monitoring, parameter self-tuning control of additive manufacturing equipment are becoming a research hotspot. Either the research on mechanical behavior of additive parts based on damage failure analysis and life prediction or the performance evaluation and verification technology based on components and characteristic structures have begun to attract the attention of engineering application departments. Based on the analysis of the technology development trend, the development goal of laser additive manufacturing technology in the aviation field in 2035 and the corresponding policy and environmental support and guarantee needs are proposed, and the technical development roadmap in 2035 is put forward. In 2025-2035, the control technology of microstructure, property and deformation for additive manufacturing of ordinary metal, intermetalliccompound, Nb-Si and ceramic based material is to be made a comprehensive breakthrough, the performance verification is to be basically completed, the functional assessment has been partially completed, and some products are to be entered mass production. Important load-bearing structures of aircraft and rotating parts of aeroengine made by additive manufacturing are to be widely used.

Wire arc additive manufacturing (WAAM) is an additive manufacturing technology with high deposition rate that produces a variety of high-performance metal structures layer by layer stacking. The research on WAAM technology of large and medium complex aluminum alloy and titanium alloy for aviation equipments has been widely concerned. In this paper, the WAAM technical definition, classification, forming system and principle are discussed. The recent research progress in the microstructure properties, metallurgical defects, quality improvement and technical application of typical components of aluminum alloy and titanium alloy formed by WAAM in aerospace field both at home and abroad is reviewed. The key common problems in the WAAM forming large and medium complex components of aviation equipments are analyzed, and the 2035 WAAM forming technology route planning map is proposed. In 2035, the "shape control" and "property control" technology of WAAM aluminum alloy and titanium alloy component is to be mastered; the large and medium complex structure components of aluminum alloy and titanium alloy which formed by WAAM are achieved comprehensive application in aviation equipment.

Additive manufacturing technology has a broad development prospect in the field of aviation equipments. As an important metal additive manufacturing process, the electron beam additive manufacturing is in a rapid development stage. The wire-feed electron beam additive manufacturing can meet the requirements of rapid and low-cost manufacturing of aviation large size structural parts and can be used to repair high-value damaged parts. Electron beam selective melting has obvious advantages in the manufacturing of complex structures and refractory alloy parts. Based on the analysis of the state-of-arts of the electron beam additive manufacturing technology, the roadmap of the electron beam additive manufacturing for aviation equipments in 2035 is comprehensively analyzed and drawn from the five aspects of development needs, objectives, common key technologies, applications, strategic support and guarantee in order to provide reference for the development of the electron beam additive manufacturing technology of aviation equipments. In 2035, a perfect additive manufacturing standard system is to be built; and electron beam additive manufactured key load bearing components for airplane andaeroengine realize mass production and application.

Laser additive repair technology is suitable to repair the metal parts of military aircraft. It is an important thrust to prolong the flight service life and improve the ability of independent maintenance. This paper introduced the characteristics of laser additive repair technologies such as selective laser melting forming, laser direct deposition forming, laser cladding and laser arc composite additive manufacturing. The common types of defects with different scales, such as edge collapse, surface spheroidization, porosity and crack in the process of laser additive repair were described, and the corresponding control methods were proposed. The laser energy density, overlap ratio, feeding speed of filler materials, shielding gas flow, time parameters and scanning path of laser additive repair technology were summarized, and the repair performance was improved by the application of external energy field and optimization design of special filler materials. Finally, the application of laser additive repair technology in the maintenance of aircraft wing beams, turbine blades, single crystal blades, landing gear and other metal parts was listed. The future research trend of laser additive repair technology in auxiliary system design, multi energy field fusion, evaluation standard formulation was emphasized, the research and development of mobile laser additive repair equipment were discussed.

Ti-6Al-4V(TC4) titanium alloy is a kind of α+β type two-phase titanium alloy widely used. However, due to the microscopic defects in additive manufacturing titanium alloy, its mechanical properties are lower than the forging level, and post-treatment is usually required. Therefore, it is necessary to further study the additive manufacturing process and post-treatment of TC4 titanium alloy. In this paper, the microstructure and comprehensive properties of titanium alloy were analyzed by the changes of common process parameters such as energy input power and scanning strategy in the additive manufacturing process, and the influence of other process parameters such as protective gas type, substrate thickness, powder size and other factors in the additive manufacturing process was introduced. The influence of common heat treatment methods after additive manufacturing on its microstructure and mechanical properties was also comprehensively analyzed, and the influence of new post-heat treatment methods, such as vacuum heat treatment and cyclic heat treatment, as well as the influence of multiple post-treatment and comprehensive use of heat treatment were summarized. Generally speaking that the reasonable selection of additive manufacturing process parameters and the application of post-heat treatment method are the basis for obtaining titanium alloy components with excellent performance. The comprehensive use of various heat treatment methods or other post-treatment methods and heat treatment are the effective ways to further improve the performance of titanium alloy components in additive manufacturing. To establish a uniform selection standard for additive manufacturing process parameters and post-processing process is the key to the future development of additive manufacturing.

Nickel-based superalloy (GH4169) and Si₃N₄ ceramics were connected by AgCuTi composite active filler and high purity W foil which acts as interlayer. The effects of temperature on the microstructure evolution and mechanical properties of GH4169/ Si₃N₄ brazed joint were systematically studied. The results show that the effective connection of GH4169/Si₃N₄ brazed joint can be realized by using AgCuTi+W composite filler. The microstructure of the joint is GH4169/TiNi₃+TiCu+TiCu₂+Ag(s, s)+Cu(s, s)+W+TiN+Ti₅Si₃/Si₃N₄. When the brazing temperature is low, the Ti element in liquid filler diffuses to less of the ceramic interface with the filler, and no obvious reaction layer is formed; when the brazed temperature increases to 880 ℃, Ti is enriched on the ceramic side, forming a thickness of 2 μm TiN and Ti₅Si₃ reaction layer. At this time, the shear strength of the joint is the highest, reaching 190.9 MPa. With the increase in brazing temperature, the content of Ti-Cu compound, which is a brittle compound, increases and the mechanical properties of the joint are greatly reduced. The fracture results show that during the shear process, the crack initiates in the interlayer, and then diffuses into the Si₃N₄ ceramic matrix, and finally breaks on the side of Si₃N₄ ceramic.

Owing to novel design concepts and their unique properties, high-entropy alloy (HEA) has become a hot topic in material science. At present, the studies and applications of high-entropy alloy are still mainly limited to the preparation and synthesis of materials. With its wide application in industry, it must involve the research of high-entropy alloy in welding field. This paper describes the welding of high-entropy alloy with the same material, welding between high-entropy alloy and dissimilar material, and welding between dissimilar material with high-entropy alloy as filler material. The paper focuses on analyzing the welding method, high entropy alloy components, the initial state of welding and welding parameters, and other factors on the joint organization and properties. While the high-entropy alloy is mainly applied as filler material, the high entropy effect and hysteresis diffusion effect for interface controlling are particularly important. Finally, the high-entropy alloy coatings under different preparation methods are analyzed in detail, introducing the cladding process, the addition of microelements, the effect of post-heat treatment, and comparing the wear resistance high-entropy alloy coatings under the laser melting process. By summarizing the research and application of high-entropy alloy in the welding field, it is pointed out that the current problems are that the corresponding standard between high-entropy alloy system and welding process has not been established and the formation mechanism of defects has not been clarified. The future research directions of high entropy alloy in welding field are proposed.

GH3536 superalloy was fabricated using Selective Laser Melting (SLM) to investigate the effect of process parameters including the laser power and scanning speed on the density, microscopic defects and surface quality of GH3536 samples. According to the measurement of density, it can be found that the density of samples increases rapidly when the laser energy density is less than 57.0 J/mm³, the density of samples fluctuates within the range of 8.30 g/cm³-8.35 g/cm³ as the laser energy density increases from 57.0 J/mm³ to 187.0 J/mm³, while the density of samples decreases slightly when the laser energy further increases. The conclusion is that the inadequate or excessive energy input reduces the density of samples. The metallographic observation shows that there are a large number of lack-of-fusion defects when the laser energy is insufficient. However, when the input laser energy is too much, many evenly distributed microcracks and gas pores appear inside of samples, indicating that defects are the main reason for low density of samples. The optimal process parameters of SLM-processed GH3536 alloy are determined by the statistical analysis of spatter particles which might cause irregular defects. Tensile properties of the sample fabricated under 175 W and 700 mm/s are tested at room temperature and the results show that the SLM-ed GH3536 superalloy has good tensile properties at room temperature.

The light-weight and high-stiffness metal lattice sandwich structure formed by selective laser melting has an important application prospect in aerospace, military and other fields. In this study, the response of square lattice sandwich panels with different core spacings under three-point bending was analyzed by finite element analysis, and the results were verified by experimental samples formed by selective laser melting. The results show that there is a linear relationship between the core spacing and cylindrical bending stiffness when the core spacing is within a certain range, the influence of core spacing on cylindrical bending stiffness is very significant and the influence of core spacing on the cylindrical bending stiffness of the square lattice sandwich panel of 45° is greater than that of the square lattice sandwich panel of 0°. The cylindrical bending stiffness of square lattice sandwich panel of 0° and 45° is basically the same under the same relative density when the relative density is within a certain range, which means that they have similar cylindrical bending stiffness under the same weight. When the relative density is less than 5%, the relative density has a significant influence on the cylindrical bending stiffness, and the influence decreases when the relative density exceeds 5%. With the increase of the core spacing, the stress concentration area is transferred from the part of panel under the loading pad to the ends of cores between the support pads due to the reduction of the cylindrical bending resistance of the lattice structure. According to the mechanical analysis, the initial load prediction formula for the yield and plastic stages can be proposed, The comparison between the theoretical results and the FEA results shows that the relative error is less than 13.6%, indicating that the formula is relatively accurate. The experimental results are in good agreement with the FEA results, especially for the cylindrical bending stiffness, the relative error between the FEA value and the experimental value is only less than 6.5%, indicating that the three-point bending deformation and mechanical properties of the lattice sandwich panel can be effectively predicted by FEA.

WC is one of the cladding synthetic materials that effectively improve the surface tribological properties of TC4 alloy, but it is easy to produce residues in the coating, which always plagues the quality and performance of the coating. In this study, TC4+WC titanium wear-resistant coatings with different WC addition ratios (5%, 10% and 15% (mass fraction /%)) were prepared on the surface of TC4 by coaxial powder feeding laser cladding technology, and the macrostructure, microhardness and tribological properties of the coating were analyzed and studied, focusing on the melting and residue mechanism of WC in the molten pool. The results show that the addition of WC does not affect the types of phases formed in the coatings. The precipitated phases mainly include in-situ TiC and matrix phases α-Ti and β-Ti. Among them, TiC and the remaining WC particles in the coating form a coherent package mosaic structure phase. The decomposition of WC in the molten pool is prevented, leading to the remaining WC is prone to residue and agglomeration. The amount of WC added is positively correlated with the microhardness of the coating. As the WC content in the material system gradually increases, the wear resistance of the coating gradually increases, and compared with the TC4 substrate, the wear rate of the coating decreases by about 21.1%, 38.2%, and 56.1%, respectively, but the residual WC leads to local stress concentration in the friction and wear process of the coating, the tribological performance fluctuates significantly.

According to the repair demand of aircraft 30CrMnSiA high-strength steel pull rod, the laser cladding process research and pull rod repair were carried out using gas atomized 30CrMnSiA powder as cladding material. The effects of different process parameters on forming quality were compared. The microstructure, mechanical properties and wear resistance of the cladding area under the optimal laser process were studied, and the damaged part of the pull rod was repaired by this process and dimensional measurement was carried out. The results show that using the optimal laser cladding process, the cladding layer with good metallurgical bonding with the base metal and dense microstructure can be obtained. The cladding layer is composed of columnar or honeycomb shaped ferrite and surrounding martensite. The microhardness of the cladding layer is about 475HV, about 36% higher than that of the base metal, and the average tensile strength of the joint is about 9% higher than that of the base metal. Compared with forged 30CrMnSiA steel, the depth of wear track of the cladding layer is reduced by 27.7%, and the width of wear track is also reduced by 35.2%, which means better wear resistance. By using this process, a repaired pull rod with good cladding quality, satisfactory dimensional accuracy and basically no thermal deformation is obtained, so the qualified products are delivered.

Turbine blades of long-life civil aircraft and gas turbines are affected by high temperature oxidation during service, which greatly reduces the surface strength under complex working conditions and significantly shortens the service life. Therefore, oxidation resistance is one of the most specific properties that must be considered in the application of turbine blades. The influence of the different drilling processes for cooling holes on the oxidation behavior of Ni-based SX (single-crystal) superalloy at 980℃ and 1100 ℃ was investigated. The difference in the oxidation mechanism of the cooling holes under different drilling processes provided a basis for the establishment of the blade life model under service conditions. The results indicate that the film cooling holes processed by millisecond laser exhibit poor oxidation performance, and all oxidation kinetic curves basically obey the parabolic or linear law. In the initial oxidation stage of the millisecond laser specimen, the oxidation reaction is primarily determined by the growth pattern of outer NiO. Subsequently, a three-layer oxide layer（(Ni, Co)O-Spinel phase layer-α-Al₂O₃） gradually formed around the hole. There are relatively micro-holes under the internal α-Al₂O₃ layer and the γ'-free zone, which makes the oxide layer easy to exfoliate. Discontinuous α-Al₂O₃ is rapidly formed in the initial oxidation stage of the picosecond laser specimen, and then connected to each other to form the dense α-Al₂O₃ layer.

The microstructure characteristics and formation mechanism of linear friction welded (LFW) TC4-DT damage-tolerant titanium alloy joint were investigated . The microstructure of each zone of the joint was analyzed in detail by using an optical microscopy and a scanning electron microscopy; the microhardness distribution of the joint was tested by means of a microhardness tester. The results show that dynamic recrystallization occurs in weld zone (WZ); the WZ temperature exceeds the β-transus temperature during welding, and both β→α′ and β→α phase transformation occur in WZ under rapid cooling after welding, resulting in a large number of α′ martensite and secondary lamellar α are formed. Due to the high deformation resistance of TC4-DT titanium alloy, the thermo-mechanically affected zone (TMAZ) of this joint is relatively narrow. The structure of the TMAZ is elongated, deformed and broken seriously under the strong thermo-mechanically coupling effect. Moreover, a few α′ martensite and a large number of secondary lamellar α are formed in TMAZ under the condition of rapid cooling after welding. The microstructure characteristics of α colony with different orientation of the base metal (BM) is basically preserved in the heat affected zone (HAZ). However, due to the influence of heat, the mutual diffusion of elements occurs at the α/β phase boundary in α colony, the interlayer β is consumed, and the primary α grows up. The refined crystalline strengthening and second phase strengthening of the WZ microstructure, the strain strengthening and second phase strengthening of the TMAZ microstructure, and the growth of α phase in the HAZ make the microhardness of above zones higher than that of the BM.

The friction extrusion additive manufacturing (FEAM) process of aluminum 6061-T651 cylindrical bar was successfully achieved by using independently developed solid-state friction extrusion additive equipment. The forming characteristics, microstructure features and mechanical properties of the final specimen obtained under different rotational speeds were comparatively analysed and discussed. The results show that for a given transverse movement speed of 300 mm/min, a fully dense single-channel double-layer specimen with thickness of 2 mm and 4 mm without any internal defects can be obtained by using the rotational speed of 600 r/min and 800 r/min respectively. The final specimen achieved under the higher rotational speed presents a flat interface, a narrower deposition layer, and a rougher surface because the effects of friction and extrusion experienced by the rotational shoulder are weakened during the deposition process. The plastic deformation and thermal cycle experienced by the bonding interface under 600 r/min are more significant than those under 800 r/min, and the grains are refined to 6.0 μm. The softening degree of the interface obtained under 600 r/min is more serious, and the hardness in this region is only 52.7%-56.2% of the value of the as-received feed rod, while this value can reach 56.0%-61.3% of the hardness of the base material. The final specimen attains a good comprehensive mechanical property. The ultimate tensile strength of the final specimen obtained under rotational speeds of 600 and 800 r/min can reach 66% and 70% of the value of the as-received feed rod respectively, while the percentage elongation after the break can reach 212% and 169% of the value of the base material respectively. The tensile properties of 6061 aluminum alloy prepared in this paper have obvious advantages compared with those of other Al-Mg-Si alloys fabricated by other well-developed additive manufacturing processes.

Based on the traditional manufacturing technology, the “classic” structure, which has a large mass and many weak parts of fatigue is difficult to satisfy the development needs of future fighter aircraft. The innovative structures ( three-dimensional bearing overall structure, bionic structure, gradient metal structure and micro truss lattice structure) based on the advantages of additive manufacturing technology characteristics, breaking through the shackles of traditional structures, with lightweight, long-life, low-cost and other characteristics, can greatly improve the quality of the body platform, providing an effective technical way for the future development of new fighter aircraft. Taking the fuel pipe joint, ring radiators and three-dimensional frame beam integral structure as examples, this paper expounded the whole process of integrated development of new additive structure design and manufacturing, and compared with the original traditional manufacturing scheme, achieved significant benefits, such as substantial weight loss, improvement of finished product rate, and reduction of fatigue weak parts. In addition, the reference significance of cross-domain technologies such as fiber optic sensing and construction structure to the innovation of aircraft structure was also discussed.