With the increase of the thrust-weight ratio of the aero-engine, CMC-SiC composites with low density, high strength and toughness, high thermal stability, long lifetime, good ablation resistance and oxidation resistance need to be developed to meet the requirements of the complicated and aggressive environments in the aero-engine. The characteristics, fabrication methods, applications on the hot components of the abroad advanced aero-engines, the domestic research achievements and the open problems of the CMC-SiC composites were introduced. The research tendencies in the high performance fibers, parts design and fabrication, environmental barrier coatings, non-destructive testing technologies, evaluation and verification method and repairing technologies were put forward.

Based on the brief review of accelerated developing status of aircraft power technology in the world, the present status and developing trend of key materials technology for aero-engine were analyzed. In accordance with the idea of "one generation of new material, one generation of new type engine", development requirements for the materials technology of the system and main parts of aero-engine were proposed. Suggestions for improving development and application level of the materials technology in China were presented from aspects of quality stability and technical maturity, investigation and verification for engineering, materials system and data, composite materials, airworthiness certificate, etc.

With the development of basic theoretical research and equipment, laser additive manufacturing technology is widely used in the manufacture of large complex components. However, the internal stress in laser additive manufacturing process tends to result in distortion and cracking. Stress and deformation control has become an urgent issue in laser additive manufacturing process. In this paper, research progress of residual stress in laser additive manufacturing was reviewed from various aspects such as residual stress forming mechanism, test methods, control measures. Furthermore, the main problems and research directions were proposed for the research of stress and deformation control technology, which provides guidance for the research of "shape control" in laser additive manufacturing.

The application and new development trend of metal additive manufacture technique were introduced, as well as the characteristic and NDT difficulty of metal additive manufacture products. The research progress of NDT was analyzed in emphasis, including the classification of metal additive manufacture technique, the characteristics of defect and microstructure, the influence of defects on mechanical properties, the latest development of NDT methods and standards. Based on that, the key issues that will be focused were summarized at last, that is the application of new NDT methods, on-line monitoring technology, numerical simulation, measurement and characterization of stress, as well as the establishment and development of NDT standards.

Currently, the utilization efficiency of energy still remains at a low level, although the depletion of fossil fuel is appoaching. Therefore, it is of great significance to develop new materials and technologies for energy-saving and environment protection. Phase-change materials (PCM), which can absorb or release heat through inversible phase change, are very promising in the fields of heat storage and thermal management. In this paper, the characteristics and classification of PCM were introduced briefly in the first section, and then the application and development status of PCM were reviewed and analyzed detailedly. In the third part, the main problems of PCM were pointed out, and the related research work and recent research progress were analyzed and discussed. Finally, it was pointed out that optimizing material properties through new functional composite technology, designing new material system, expanding new application fields are the main development directions of phase change energy storage materials.

Graphene-reinforced aluminum matrix nanocomposites were successfully synthesized through ball milling and powder metallurgy. The tensile strength and yield strength of graphene-reinforced aluminum matrix nanocomposites are remarkably enhanced by adding graphene nanoflakes(GNFs). Importantly, the ductility properties are remained excellently, which is firstly found in the second phase reinforced metal matrix nanocomposites. The microstructures were observed by OM, SEM and TEM method. And the tensile properties were tested.The results show that graphene nanoflakes are effectively dispersed and well consolidate with aluminum matrix, however, chemical reactions are not observed. The original structured characteristics of graphene nanoflakes are preserved very well. The average tensile strength and yield strength of nanocomposite are 454MPa and 322MPa, respectively,which are 25% and 58% higher than the pristine aluminum alloy at a nanofiller mass fraction of 0.3%, while the ductility increases slightly. The relevant mechanisms of strengthening and toughening enhancement are discussed on the base of 2D and wrinkled structured properties of graphene nanoflakes.

Pitting behavior of 304 stainless steel in 3.5% (mass fraction) NaCl solution was investigated by dynamic potential electrochemical impedance spectroscopy (DEIS) and time scan electrochemical impedance spectroscopy (TSEIS). The results of DEIS show that metastable pits emerge at the potential (0.02V) which is more negative than the pitting potential (0.15V), and the generation and passivation of metastable pits are stochastic. The steady pitting potential which got from DEIS is negative than breakdown potential which got from dynamic potential polarization by 0.05V. The results of TSEIS indicate that pitting nucleation can happen just when the thickness of passivation film has been reduced to some extent. It reveals the characteristics of the structure of electric double layer and passivation film by analyzing element parameter of the equivalent circuit.

Decanoic-palmitic acid/SiO₂ composite phase change materials were prepared with SiO₂ as carrier material and decanoic-palmitic acid as phase change material. The effect of every factor on moisture absorbing and desorbing performance and temperature control performance of composite phase change materials was studied by uniform design and multivariate nonlinear regression. The results show that primary and secondary sequence of factors affecting performance is solution pH value> mole ratio between absolute alcohol and tetraethyl orthosilicate> mole ratio between decanoic-palmitic acid and tetraethyl orthosilicate> mole ratio between deionized water and tetraethyl orthosilicate> ultrasonic wave power. The optimized preparation plan is solution pH value 3.62, ultrasonic wave power 100W, mole ratio between deionized water and tetraethyl orthosilicate 9.67, mole ratio between absolute alcohol and tetraethyl orthosilicate 5.21, mole ratio between decanoic-palmitic acid and tetraethyl orthosilicate 0.52.

The current high entropy alloys' studies are most in block, powder, coating, film and other areas. There are few studies of high entropy alloys in other areas and they are lack of unified classification. According to the current high entropy alloys' research situation, The paper has focused on the classification on all kinds of high entropy alloys having been researched, introduced the selecting principle of elements, summarized the preparation methods, reviewed the research institutions, research methods and research contents of high entropy alloys, prospected the application prospect of high entropy alloys, put forward a series of scientific problems of high entropy alloys, including less research on mechanism, incomplete performance research, unsystematic thermal stability study, preparation process parameters to be optimized, lightweight high entropy alloys' design, the expansion on the research field, etc, and the solutions have been given. Those have certain guiding significance for the expansion of the application of high entropy alloys subjects in the future research direction.

At present, ablation is still considered as one of the most effective, reliable, mature and economical thermal protection methods, which is widely used in thermal protection systems (TPS) of aerospace flight vehicles. Recent years, series of advanced lightweight ablative composites (LAC) were developed driven by major projects such as manned space flight, lunar exploration program, deep space exploration, and near space flight vehicles. Particularly, material's developing, engineering application and corresponding applied basic research of LACs filled in honeycombs and new LAC integrated ablation & insulation were emphatically introduced. Furthermore, complicated ablative mechanisms and synergistic effects of multiple thermal protection methods were explored. With the development of advanced TPS demand, multi-functionalization, compatibility and integration are the main development tendency of LAC for earth reentry or atmospheric entry aerospace flight vehicles.

High strength intermediate modulus carbon fiber composites are still the main aviation composites in the world at present and for a long time to come. In recent year, based on the experience of high-strength carbon fiber composites, the industrialization technology of high strength intermediate modulus T800 grade carbon fiber have been broken through in China, and the resin matrix, prepreg and manufacturing process were analysized systematically for the high toughness composites reinforced by Chinese T800 grade carbon fiber. The impact resistance of the resin matrix composites reinforced by Chinese T800H grade carbon fiber is at the same level with that of foreign composites, and the hydrothermal resistance of high toughness epoxy resin matrix composites is better than that of foreign composites with the same CAI level. At the same time, the prepreg of Chinese T800H grade carbon fiber reinforced high toughness composites has excellent process ability, and it can meet the requirements of manual-layup, ATL and AFP. Based on the T800 grade composites, the main research goal is to improve the compression mechanical properties, elastic modulus and CAI based on BVID(barely visible impact damage) for high strength intermediate modulus carbon fiber composites in the future.

The properties and application status of 6000 series aluminum alloys in automotive body panel were introduced. Besides, the precipitation behavior, strengthening mechanism, texture evolution and the influence of alloying element to properties were also discussed in detail. Additionally, the conventional heat treatment and the effect of pre-aging or pre-straining to bake hardening were described. Then some current problems and research directions about 6000 series aluminum alloys for automotive body were discussed.

The research of SiC_f/SiC ceramic matrix composites (CMCs) as well as their applications in aero engines has obtained rapid development recently. This is owing to the large quantity of coupon tests performed on various properties of these materials, and the establishment of corresponding databases. Here, the physical and mechanical properties of CMCs developed by SNECMA, NASA and GE were reviewed. The influence of fabrication techniques on the properties of materials were discussed with an emphasis on tensile properties. Meanwhile, the service performances of these materials were summarized, including oxidation, water vapor/oxygen environmental resistance at high temperature, fatigue and creep behaviors, resistance to thermal shock and foreign object damage, along with the mechanism of damage and failure in environments such as heating, loading, water and oxidation. At last, some suggestions about domestic further research on performances testing for SiC_f/SiC ceramic matrix composites were proposed.

Wire and arc additive manufacturing (WAAM) was investigated by tungsten inert gas arc welding method (TIG), in which φ1.2mm filler wire of aluminum alloy 5A06(Al-6Mg-Mn-Si) was selected as deposition metal. The prototyping process was conducted by a TIG power source (working in AC mode) manipulated by a four-axis linkage CNC machine. Backplate preheating temperature and arc current on deposited morphologies of single layer and multi-layer were researched. The microstructure was observed and the sample tensile strength was tested. For single layer, a criterion that describes the correlation between backplate preheating temperature and arc peak current, of which both contribute to the smoothening of the deposited layer. The results show that the layer height drops sharply from the first layer of 3.4mm and keeps at 1.7mm after the 8th layer. Fine dendrite grain and equiaxed grain are found inside a layer and coarsest columnar dendrite structure at layer boundary zone; whereas the microstructure of top region of the deposited sample changes from fine dendrite grain to equiaxed grain that turns to be the finest structure. Mechanical property of the deposited sample is isotropic, in which the tensile strength is approximately 295MPa with the elongation around 36%.

With waste walnut shell as raw material, biomass based porous active carbon was made by microwave oven method. The effects of microwave power, activation time and mass fraction of phosphoric acid on adsorptive property of biomass based porous active carbon in the process of physical activation of active carbon precursor were studied by response surface method and numerical simulation method, the preparation plan of biomass based porous active carbon was optimized, and the optimal biomass based porous active carbon property was characterized. The results show that three factors affect the adsorptive property of biomass based porous active carbon, but the effect of microwave power is obviously more significant than that of mass fraction of phosphoric acid, and the effect of mass fraction of phosphoric acid is more significant than that of activation time. The optimized preparation conditions are:microwave power is 746W, activation time is 11.2min and mass fraction of phosphoric acid is 85.9% in the process of physical activation of activated carbon precursor by microwave heating method. For the optimal biomass based porous active carbon, the adsorption value of iodine is 1074.57mg/g, adsorption value of methylene blue is 294.4mL/g and gain rate is 52.1%.

The research status on theoretic models and the coupling relationships of Orowan strengthening, dislocation strengthening, load-bearing effect of the reinforcement strengthening and others strengthening are successfully described in this study for particle-reinforced metal matrix composites(MMCs) with a volume fraction lower than 14%. Some conclusions can be obtained:Orowan strengthening and dislocation strengthening stress can be enhanced by increasing volume fraction, decreasing size of reinforcement and improving homogeneous distribution of reinforcement, load-bearing strengthening stress can also be enhanced by increasing volume fraction; yield strength and ductibility of MMCs can be enhanced much more by increasing load-bearing strengthening stress and plastic deformation region and adopting the material design method of metal matrix surrounded by particles with microstructural inhomogenous distribution; grain boundary strengthening and Peierls-Nabarro stress can also affect the yield strength of MMCs as a part of matrix strengthening, solid solution strengthening can be ignored usually; there are three coupling relationships for the sum strengthening contributions:linear summation, multiplicative combination and the root of the sum of the squares. The linear summation and multiplicative combination can be applied to nanoparticle-reinforced MMCs, the linear summation is generally applicable in the case when there are few factors influencing the strength, the multiplicative combination is the most commonly used method. The root of the sum of the squares is applied to micronparticle-reinforced MMCs.

SiC matrix ceramic composites (CMC-SiC) are considered as the potential primary structural materials in advanced gas turbines because of their low density, good oxidation resistance and high-temperature strength. However, CMC-SiC suffers from serious degradation in the gas environments. With the protection of environmental barrier coatings (EBCs), CMC-SiC composites can be possibly applied as hot components with long lifetime in the aero-engine. The materials selection requirements, development history, preparation process, assessment technologies and characterization methods of EBCs materials system were introduced in this paper. The open problems of EBCs materials system such as high volatile rate, low operating temperature during service and low crystalline fraction, low density of the coatings during the preparation process were summarized and analyzed. The research goal and development direction in the EBCs system optimization, fabrication process development and evaluation and assessment platform were put forward.

The three-dimensional (3D) woven composites have the advantages of strong structural design ability, overall near-net shape of complex components and high impact damage tolerance, and have become the focus of the development of new materials in the aerospace industry. In recent years, the structural design, micro-modelling and performance analysis of 3D woven composites have been rapidly developed and achieved substantial achievement. The development of multi-axial woven structures, fine modeling, and automated continuous production are the development trends of 3D woven composites. In this paper, the structural characteristics of typical 3D woven preforms were introduced. The quasi-static mechanical properties of 3D woven composites with different structures were discussed. The research progress of the micro-structure modelling, theoretical analysis and numerical simulation of 3D woven composite materials were reviewed. The typical applications of 3D woven composite materials in aerospace were listed, which can provide reference for the application research of 3D woven composite materials.

The historical evolution, the latest research progress and the related industrial status of equipment development of the three major photopolymerization-based ceramic 3D printing technologies were reviewed, i.e. stereolithography (SL), digital light processing (DLP) and two-photon polymerization (TPP). The characteristics of feedstock materials, printing process, post-treatments and final ceramic properties were summarized and discussed.Meanwhile, some of the issues and challenges such as incapability of mass production and low efficiency persist, and high-end industrial application scenarios of printed parts still need to be excavated. Therefore, new materials, new theories and new technologies regarding ceramic photopolymerization-based 3D printing should be further developed in order to seek for efficiency and application breakthroughs. Finally, it was suggested that structural-functional integral/gradient manufacturing and multi-material/multi-process comprehensive and efficient manufacturing are the important development directions of ceramic 3D printing technology in the future.

Metamaterials, man-made materials, enable us to design our own "atoms", and thereby to create materials with unprecedented effective properties that have not yet been found in nature. Smart metamaterial is one of those that is an intelligent perceptive to the changes from external environments and simultaneously having the capability to respond to thermal and mechanical stimuli. This paper can provide a review on these smart metamaterials in perspective of science, engineering and industrial products. We divide smart metamaterials according to what they are tuning into: optical, mechanical, thermal and coupled smart metamaterials. The rest of two techniques we addressed are modelling/simulation and fabrication/gene engineering. All of these types smart materials presented here are associated with at least five fundamental research: coupled mechanism of multi-physics fields, man-made design for atom/molecular, metamaterials coupled with natural materials, tunability of metamaterials, and mechanism of sensing metamaterials. Therefore, we give a systematic overview of various potential smart metamaterials together with the upcoming challenges in the intriguing and promising research field.

Based on the fact that cold spraying (CS) was increasingly attracting more and more attention from researchers worldwide, this paper made detailed summarization and discussion on fabricating composite coatings via CS according to the published literature. Firstly, the powder preparation methods prior to spraying and the effects of processing parameters on deposition of composite coatings were explored. And then, the fabrication of metal-metal, metal-ceramic, metal-intermetallics and nano-composite coatings were summarized. Eventually, the present problems and potential applications existing in composite coatings fabricated by CS were discussed.

The energy crisis and environmental pollution problem is increasingly serious on a global scale, however the rapid development of photocatalytic technology brings the dawn to solve the problem, and the photocatalytic materials system as a basic element has become the focus. The photocatalytic degradation of organic pollutants in water was focused in this article, and the development status of photocatalytic technology, nine types of photocatalytic materials and their properties, mechanism of action and the application of research, as well as modification methods of the materials were summarized. Finally, it was proposed that the materials still has the problems of low solar energy utilization, low quantum yield, and insufficient photochemical stability at the current stage, nevertheless the new material system of metal-organic framework (MOF) and the modification methods of micro/nano mesoporous, multi-hole composite, Z-scheme semiconductors provide a broader space for the exploration of photocatalytic materials.

Aluminum alloy is the preferred material for lightweight structure, and has broad application prospects in aerospace, transportation and ships. The additive manufacturing of aluminum alloy possesses outstanding advantages and potential on fabricating complicated three-dimensional precision structural parts. Furthermore, this method can be characterized by its high efficiency and excellent structural properties. With regard to the rapid development of the aluminum alloy additive manufacturing, the research status and latest achievements of aluminum alloy fabricated with additive manufacturing from the aspects of structure and performance, precision and quality, controlling of defects and numerical simulation, and the shortcomings of current research were summarized. Based on these, the key issues that will be focused were summarized at last, including realizing the control of the micro-structure, clarifying the forming mechanism of the stress, improving the forming accuracy, and studying the distribution law of the temperature field in the forming process.

Hydrophobic SiO₂-glass fibers aerogels were prepared by sol-gel process with tetraethoxysiliane (TEOS) and methyltriethoxysilane (MTES) as the silica source, glass fibers as reinforcement, followed by ambient pressure drying. The physical properties and microstructure of silica aerogels were characterized by nitrogen adsorption/desorption tests, Fourier transform infrared spectroscopy, thermogravimetric and differential thermal analysis, scanning electron microscopy, high resolution transmission electron microscopy, contact angle measurement and mechanical testing. The influences of acid concentration and soaking time during pretreatment of glass fibers on the densities of SiO₂-glass fibers aerogels were investigated. The results show that when the pretreatment condition of glass fibers is soaking 0.5h at 2.5mol/L hydrochloric acid, the obtained monolithic SiO₂-glass fibers aerogels exhibit the lowest density of 0.12g·cm^-3 and pore size is in the range of 2-50nm, the water contact angle is 142°, the thermal stability temperature reaches 500℃, the compressive strength is 0.05MPa, and the elastic modulus is 0.5MPa.

The application background and key role as well as the basic performance requirements of ceramic cores and shells used for the investment casting of superalloy hollow blade were introduced,and the future development direction of ceramic cores and shells was described. The raw materials of the ceramic cores and shells, together with the manufacture methods and their influence on the properties were reviewed respectively. The research status and existing problems of leaching technics of ceramic cores were introduced. In addition, the important influence of positioning accuracy and the consistency of ceramic cores and shells on the quality of superalloy hollow blade was evaluated.

Continuous fiber reinforced high-performance thermoplastic composites have gradually attracted the attention of the composite industries due to their unique advantages such as light mass, high strength, good impact resistance, short molding cycle, secondary molding and waste recycling. The application status of continuous fiber reinforced high-performance thermoplastic composites was introduced in this paper starting from several kinds of high-performance thermoplastic resins. Moreover, the forming and properties of continuous fiber reinforced high-performance thermoplastic composites were also summarized in detail. At last, the future development trend of domestic continuous fiber reinforced high-performance thermoplastic composites was summarized from three aspects including application demand, molding process and material properties, in order to promote the structural design and application of continuous fiber reinforced high-performance thermoplastic composites.

Wire arc additive manufacturing (WAAM) attracts much attention due to its unique feature of rapid near net shape forming without die. It has the potential to become an advanced manufacturing technology that can break the bottleneck of alloy development and industrial application for aluminum materials. Wire arc additive manufacturing technology originates from traditional arc welding, and both of them use high-energy arc as heat source and metal wires as raw material. The WAAM technology and equipment development, the solidification and solid state phase transformation performance, microstructures, metallurgical defects as well as mechanical property of aluminum alloys were reviewed. The technique prospects of hot wire and multi-wire additive manufacturing, the unique fabrication manner and the exclusive phase transformation microstructure were discussed. The WAAM-specialized approaches to address the issues of poor manufacturing accuracy, serious porosity and cracking, and unsatisfied mechanical property, including fabrication system development, metallurgical defect controlling, alloy composition and microstructure design and heat treatment optimization were proposed. Such proposals are expected to facilitate the rapid development of high-end, customized and distinguished aluminum alloys via WAAM.

Resin matrix composites have many advantages such as high specific strength and modulus, good fatigue performance, corrosion resistance, and have become the application and development trend of aero engine components under 400 ℃. Foreign research on resin matrix composites for aero engine started earlier, which have been applied in fan blades, fan casings, outer ducts, nacelles and other components of multi-engine, and developed towards the trend of better structure, higher material performance, lower manufacturing cost and higher automation degree. The development foundation of domestic resin matrix composites is good, but compared with foreign countries the application proportion of resin matrix composites in engines in not high. It is necessary to furthur improve the technical level of design, materials, manufacturing, experiment and engineering ability. In this paper, foreign development status was discussed in the field of structures, materials and processing methods of aero engine composite components, the development trend was analyzed and corresponding suggestions were given, from the aspects of building composites system for aero engine, strengthening application research and design guide, promoting the transformation of pre-research achievements and application of automation technology.

FeCrNiCoCuAl_x (x=0, 1, 2, 3) high-entropy alloy (HEA) coatings were prepared on Q345 steel by laser cladding. The effects of Al content on microstructure and properties of FeCrNiCoCuAl_x HEA coatings were studied by XRD, SEM and erosion wear tests. The results show that the HEA coatings are mainly composed by simple FCC and BCC solid-solution phases. With the increase of Al addition, the microstructure is evolved gradually from FCC to BCC. And the hardness of the HEA coatings improves significantly and the maximum value is 580HV. In 3.5%NaCl solution, the corrosion current density of FeCrNiCoCuAl_x HEA coatings decreases firstly and then increases with the increase of Al addition. And the HEA coating has the best corrosion resistance at x=1. Meanwhile, the mass loss rate of HEA coating decreases in the erosion test when the impact angle is changed from 90° to 30°, exhibiting an erosion characteristic of ductile materials. The slurry erosion properties of the HEA coating increase with the increase of Al content, and the erosion wear mechanism is evolved from forging extrusion to ploughing and micro-cutting.

To meet the needs of large composite bonding for aircraft, development, comprehensive experimental and application of adhesive materials have been carried out. Development process, adhesive bonding performance, operability and batch production of parts of adhesives are presented in brief. Traditional metal structural adhesives are widely applied to composite bonding for military use and civil use. We have made some progresses in development of toughened cyanate film adhesive and toughened BMI film adhesive. Development of high temperature resistant adhesives such as polyimide adhesive will be an important investigation area. All kinds of adhesives with different heat-resistant and chemical compositions need to be developed to meet adhesive selections for various composite bonding.

The evolution behavior of carbides in GCr15 bearing steels after spheroidization annealing, austenitization quenching and low temperature tempering was investigated by the method of quantitative metallography. Numerical simulations on the dissolution kinetics of carbide size and composition during austenitization were performed by ThermoCalc software. The results indicate that the carbide particles formed after spheroidization annealing have a multimodal distribution whilst their size distribution changes to have a single peak after austenitization and tempering, and Cr content increases slightly after austenitization; the carbide particles appear to have larger size with higher Cr content; C rich austenite is formed during austenitization through solid solution by carbides after spheroidization annealing, and then high carbon martensite is formed after quenching and results in the high hardness; Cr atoms can partition from austenite to carbide during the dissolution of carbide, lead to the increasing Cr content of rest carbide particles; the numerical simulations indicate that the carbide particles with the diameter of 200nm cannot completely be dissolved during austenitization even if its Cr content is close to the nominal Cr content of steel, and the undissolved ones may affect the precipitation of carbides during the subsequent tempering.

Laser cladding of Ni-based Ni60A+x% (SiC+Ti)(mass fraction, the same below) composite powder coating on 45 steel substrate was studied by using the method of preplaced powder. The dry friction and wear experiments of different material coatings were carried out by reciprocating friction wear tester. The microstructure and worn morphology of cladding layers were observed and analyzed by using metallographic microscope, scanning electron microscope (SEM) respectively. The results show that the prepared composite coating with dispersively distributed TiC enhanced particles are obtained in-situ, the size and number of the granular TiC gradually increase with the increase of the composite powder SiC+Ti. When the composite powder SiC+Ti reaches 60%, pores and inclusions defects exist in microstructure. When the composite powder SiC+Ti reaches 48%, wear resistance of cladding coating is the best. The wear behavior of the composite coating is abrasive wear, and the mechanism is micro cutting and extrusion spalling.

The latest research progresses on Fe-based amorphous coatings were reviewed. The typical alloy system and the classification of Fe-based amorphous coatings were clarified. The status, progress and development of the Fe-based amorphous coatings prepared by thermal spray processing and laser cladding process were discussed. The main mechanical properties and potential applications of the Fe-based amorphous coatings were also described. Furthermore, based on the main problems mentioned above, the future development of the Fe-based amorphous coatings was discussed, including the exploitation preparation technologies of high amorphous content of the Fe-based coatings, the development of the low cost and high performance Fe-based coating alloys system, the broadening application of Fe-based amorphous coatings, and so on.

Ti-Al system intermetallics and high-temperature ceramics or ceramic matrix composites, are the two kinds of light-mass heat-resistance structural materials with high potential in aerospace applications. According to the published literatures, the research advances on their welding and joining technologies, including the material weldabilities, joint properties with different welding processes and material combinations, and the progresses of studies on the application of the welding and joining technologies were reviewed, and some comments are made on the reporting advances especially in the past two decades. It is pointed out that, development of new high-temperature-tolerance welding consumables or brazing alloys, joining of dissimilar materials, and study on joint assessment and engineering application would be mainly important research areas in future.

The development status of micro-arc oxidation (MAO) technology at home and abroad was reviewed. The principle and process characteristics of MAO technology were primarily introduced. The influence factors for the microstructure and properties of MAO ceramic coatings as well as the applications of MAO technology were summarized. Also, the existing problems of MAO technology were analyzed, and it has been pointed out that MAO technology will be developed towards the direction of low energy consumption, treatment of ultra-large and complex light metal components and combining with other surface technologies in the future.

Cu(NO₃)₂·3H₂O and Ce(NO₃)₃·6H₂O were used as modifier to make Cu-Ce/TiO₂ by sol-gel method. The influences of Cu-Ce loading capacity, Cu and Ce molar ratio, sintering temperature on Cu-Ce/TiO₂ performance were explored. Then, surface morphology, particle size distribution, pore structure and optical property of Cu-Ce/TiO₂ were characterized by SEM, LPSA, BET and UV-Vis, respectively. The results show that:prepared Cu-Ce/TiO₂ shows good photocatalytic-moisture performance when Cu-Ce loading capacity is 3%, Cu and Ce molar ratio is 1:1 and sintering temperature is at 500℃. Cu-Ce/TiO₂ presents approximate sphere, with better uniformity and dispersibility and the particle size distribution is 1202.98-5364.48nm, with d₅₀ 2437.57nm. Cu-Ce/TiO₂ has pore structure, approximate to an "ink bottle" with a narrow bottleneck, with the specific surface area 105.55m²/g, hole size 0.1200-0.1246mL/g, and average pore diameter 3.44-4.02nm. Cu-Ce doping promotes to form a new energy level inside Cu-Ce/fiO₂ so as to improve the ability to capture e^- and h⁺, enhance the efficiency of photon utilization, and promote red shift of absorption sideband.

Auxetic metamaterials and structures have excellent mechanical properties such as shear resistance, impact resistance, fracture resistance, energy absorption and vibration isolation, permeability variability, synclastic curvature in bending, etc. Auxetic metamaterials have broad application prospects in the fields of aerospace, navigation, mechanical automation, biomedicine, national defense and military and textile industry. Based on the deformation mechanism of auxetic metamaterials and structure, the physical models of re-entrant mechanism, rotating rigid mechanism, chiral/antichiral mechanism, fibril/nodule mechanism, miura-folded mechanism, buckling-induced mechanism, helical auxetic yarn structure were reviewed. These models can be widely applied in various engineering applications such as light laminated plates, fluid transportation and yarn to improve their properties. Finally, prospects to the upcoming challenges and progress trends of auxetic metamaterials and structures are made.It is pointed out that the application of negative Poisson's ratio effect can help compensate the change of volume and area under the deformation of uniaxial loading. Then the shock resistance of turbine blade, antenna and car suction box can be improved. As a result, this review can provide benefits for the development of auxetic metamaterials.

The meaning and characteristics of refractory high entropy alloys were briefly described, and the preparation methods of various refractory high entropy alloys (bulk, film and coating) were summarized.The comprehensive properties of refractory high entropy alloys were emphatically expounded. It was suggested that the composition design should be optimized by constructing a special database of refractory high entropy alloys, and the manufacturability of different preparation methods should be focused on. In view of the shortcomings of high room temperature brittleness, high density and high cost of refractory high entropy alloys at present, different preparation methods could be selected according to the properties of refractory high entropy alloys for future industrial application.

The friction and wear of mechanical parts mainly occurs on the surface of the material, and about 80% of the failures of parts are caused by surface wear.Friction and wear increase the loss of material and energy, and reduce the reliability and safety.Using laser cladding technology to prepare a high entropy alloy coating on the surface of the substrate can achieve a good metallurgical combination between the coating and the substrate, so as to achieve the purpose of improving surface wear resistance.The main factors affecting the wear resistance of the high entropy alloy coating are the mechanical and physical properties of the coating material (such as hardness, plasticity and toughness), defects generated during the cladding process (such as surface roughness, pores and cracks), friction conditions (such as high temperature environment and corrosive environment).In this paper, the influencing factors and strengthening mechanism of laser cladding high entropy alloy coatings were reviewed and summarized.First of all, the influence of laser process parameters (such as laser power, laser scanning speed, spot diameter) and post-treatment processes (such as heat treatment and rolling) on the quality and performance of the coating were explained.Secondly, the influence of component element selection, high temperature environment and corrosive environment on the wear resistance of the coating was described.Finally, the problems existing in the preparation of high entropy alloy coatings by laser cladding technology were analyzed, and the future development trends were forecasted, such as developing new materials based on far-equilibrium material design theory, using electric field-magnetic field synergy or laser-ultrasonic vibration composite technology to improve the wear resistance of coatings, etc.

To analyze the deformation characteristics and the change rule of flow stress of 2219 aluminum alloy at high temperatures and high strain rates, the dynamic as well as quasi-static tensile response of 2219 aluminum alloy were investigated by using split Hopkinson pressure test(SHPB) and universal test machine. The true stress-strain curves of 2219 aluminum alloy under different strain rates and temperatures were obtained. The results show that the temperature sensitivity of 2219 aluminum alloy is high and the flow stress decreases with the increase of temperature. When the strain rates are within the range of 1000-3000s^-1, the change of flow stress is not obvious. The parameters fitted by the Johnson-Cook model can predict well the flow stress.