Current Issue https://jam.biam.ac.cn EN-US https://jam.biam.ac.cn/EN/current.shtml https://jam.biam.ac.cn 5 Continuous SiC fiber reinforced titanium matrix锛圫iC_f/Ti锛塩omposite exhibiting high specific strength, high specific modulus and high temperature resistance, shows important application prospects in the aerospace field. In this paper, the development of SiC_f/Ti composite's application, preparation, property control and testing technology is summarized, and the bottleneck problems required to be broken through are raised. SiC_f/Ti composite shows the unidirectional performance advantages, making it suitable for rotating ring parts锛坆ling, turbine disk, etc锛�, rod parts锛坱urboshaft, connecting rod, fastener, etc锛塧nd plate parts锛坅ircraft skin, etc锛�. The commonly used preparation methods of SiC_f/Ti composite materials are foil-fiber-foil锛團FF锛塵ethod and matrix coating technology锛圡CT锛�. FFF is suitable for preparing plate structural parts, and MCT is suitable for winding structural parts, such as rings, disks and shafts. The properties of SiC_f/Ti composite mainly depend on SiC fiber, titanium alloy matrix and fiber/matrix interface. The microstructure and properties of SiC fibers are highly sensitive to the preparation process, and it is one of the research focuses to obtain stable SiC fibers by regulating the reactor structure and deposition conditions. The titanium alloy matrix can be coated on the fiber surface by physical vapor deposition to prepare the titanium alloy precursor wire, which is the key to the subsequent preparation of high-quality components. The interfacial microstructure, thermal stability and mechanical properties of SiC_f/Ti composites are closely related to the coating on the fiber surface, so the control of coating type and structure is an important means to control the interfacial properties of SiC_f/Ti composites. The application of SiC_f/Ti composite materials has promoted the development of non-destructive testing technology, so researchers have carried out the basic research of ultrasonic testing, X-ray testing and acoustic emission in application of composite material testing. In order to realize the wide application of SiC_f/Ti composites, further research work should be carried out in the structural design, low-cost manufacturing, failure analysis and life prediction of composite materials in the future.

]]> The rapid development of aviation equipment such as hypersonic aircraft has put forward higher requirement for the comprehensive properties and application levels of titanium alloys. The properties of titanium alloys prepared by traditional thermal technologies have approached or reached the theoretical limit. Traditional technologies have been difficult to greatly improve the comprehensive properties of titanium alloys, and exploring graphene technology to modify titanium alloys has become an important development direction. However, it is difficult to control the interface reaction of graphene in titanium alloys. How to obtain the graphene/titanium interfaces with high bonding strength is the key to improve the performance of graphene reinforced titanium matrix composites. Based on the analysis of the problems restricting the development of graphene reinforced titanium matrix composites, this paper emphatically introduces the research progresses of microstructures, interface characteristics, static/dynamic mechanical properties, friction and wear properties, oxidation resistances, and strengthening and toughening mechanisms. The advantages and disadvantages of current solutions for dispersion uniformity, interface bonding and microstructure compactness are discussed. The challenges of interface control technology, large-scale preparation technology and performance stability of graphene reinforced titanium matrix composites are pointed out. Finally, it is proposed that such materials should be combined with theoretical calculation technologies, advanced preparation technologies and special function applications to deepen the interface optimization design and controllable preparation, and the application field expansion.

]]> The forced sweat cooling of porous media is an effective way to solve the problem of thermal protection of the leading edge of hypersonic vehicles. The pore structure and performance of porous media have a significant impact on its cooling effect and reliability. Therefore, it is very important to prepare porous materials that meet the requirements of forced sweat cooling. Herein, Ti6Al4V pre-alloyed powders were used as raw materials, and porous Ti6Al4V samples with different open porosity were prepared by compression molding combined with high-temperature sintering. The effect of the sintering temperature and holding time on the microstructures, phase compositions and mechanical properties of the samples were investigated. The results show that increasing the sintering temperature and prolonging the holding time will reduce the open porosity of the material. When the open porosity is high, the pores in the material are connected and the seepage rate is high, while the sample strength is low. When the open porosity is low, large pores in the sample are reduced and the seepage rate decreases, but the strength becomes higher. The porous Ti6Al4V sample with an open porosity of 21.8% shows the best comprehensive performance. When the porous Ti6Al4V sample is used as active thermal protection material, it can withstand flame ablation with an average heat flux of 2.5 MW/m².

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

]]> GH2132 alloy, as one of the representative materials of high-temperature alloys based on Fe-25Ni-15Cr, has become a widely used high-temperature material below 650 鈩� due to its excellent comprehensive properties. At present, the research on GH2132 alloy mainly focuses on three aspects: solid solution heat treatment, solid solution + aging heat treatment, and direct aging heat treatment. This article summarizes recent research on the alloy in these three aspects and analyzes the impact of heat treatment processes on microstructure and properties. During the solid solution treatment process of GH2132 alloy, attention should be paid to the effect of the dissolution of Laves and M₃B₂ phases on grain size to prevent grain coarsening. The alloy after solid solution exhibits the characteristics of low strength and high plasticity. The formulation of aging treatment process needs to be combined with solid solution treatment process, taking into account the influence of coupling effect and preventing occurrence 纬鈥� 鈫� 畏 transform and reduce the reinforcement effect. The microstructure of GH2132 alloy is sensitive to deformation, and the larger the deformation, the lower the aging temperature or shorter the aging time should be chosen.

]]> The hot-rolled Al-Zn-Mg-Cu system aluminum alloy was treated with single-stage solution, low temperature-long term & high temperature-short term and low temperature-short term & high temperature-long term, double-stage solution quenching systems. The effects of different solution methods on the structure and properties of Al-Zn-Mg-Cu system aluminum alloy were systematically compared and analyzed by OM, SEM, DSC, EBSD and other technical means, as well as conductivity testing methods. The results show that the selected solution quenching system will not cause the structure to overheat, and can fully dissolve the eutectic second phase of the low melting point in the structure. When 473 鈩�/20 min+477 鈩�/40 min two-stage solution quenching system is selected, the plate has the best solution effect and the lowest conductivity, which is 27.60%IACS, and the recrystallization degree of the structure is less than 50%. There are {112}銆�111銆�, {011}銆�211銆�, {123}銆�634銆� deformation texture and {001}銆�110銆� shear texture in the structure.

]]> To investigate the corrosion behavior of NiCrAl-NiC sealing coating in high-temperature molten salt environments, NiCrAl-NiC sealing coating was prepared using atmospheric plasma spraying technology. By measuring the weight loss of NiCrAl-NiC sealing coating, the dynamic changes of the coating were studied. The thermal corrosion behavior of NiCrAl-NiC sealing coating in a mixture of thiochlorate锛�75% Na₂SO₄ + 25% NaCl锛塧t 650 鈩� was discussed using scanning electron microscopy锛圫EM锛�, X-ray diffraction锛圶RD锛�, laser confocal microscopy, and other methods. The results show that after 10 h of hot corrosion experiments, the NiCrAl-NiC sealing coating exhibites a rapid weight gain state, with a weight gain rate of 32.041 mg²路cm^鈥�4路h^鈥�1. After conducting a 20 h hot corrosion experiment, the coating experienced weight loss due to the detachment of the surface oxide film. After 30 h of hot corrosion, the growth of the facial mask on the coating surface covers the entire coating. The surface morphology of the coating is uniform, and the surface pores are reduced, which can play a good role in protecting the substrate. Under the protection of a complete oxide film, the mass change rate of the NiCrAl-NiC sealing coating after a 40 h hot corrosion experiment is 0.064 mg²路cm^鈥�4路h^鈥�1. Through XRD testing, it is found that the composition of the oxide film on the surface of the coating after hot corrosion is mainly NiO and NiCr₂O₄. During the hot corrosion process, the spinel structure of NiCr₂O₄ hinders the hot corrosion of the coating, which is the main reason for the slow corrosion process of the coating.

]]> Interatomic potential is a key component of large-scale atomic simulation of materials. For scientific problems in complex environments such as high temperature, high pressure and irradiation, the interactions between atoms are often very complex. The empirical force field only considers two-body, three-body or four-body interactions between atoms. The physical assumption is simple, and it is often difficult to accurately describe the potential energy surface of complex environment. Machine learning force fields can obtain potential energy surfaces that are more accurate than empirical force fields. In this paper, a machine learning force field based on physical model is proposed for BaZrO₃, the most common perovskite system, to describe the static properties, phase stability and mechanical properties of BaZrO₃. The density functional theory database is used to train the machine learning force field based on physical model, and the static properties, phase stability and mechanical properties are calculated. For the static properties, the elastic constants C₁₁, C₁₂ and C₄₄ were computed using both a pure machine-learning force field and a machine-learning force field based on a physical model, and the simulation results were much better than the empirical force field when compared to the DFT with errors of 0.34%, 8.75% and 10.71% for the former, and 0.34%, 2.5% and 7.14% for the latter. As for the phase stability, it is found that the machine learning force field based on physical model inherits the advantage of the empirical force field in maintaining the phase stability, which is better than the pure machine learning force field. For mechanical properties, Young's modulus of four different crystal directions of BaZrO₃ are calculated. It was found that the errors between the calculated and experimental values for the machine learning force field and the machine learning force field based on the physical model were 9.22% and 1.6%, which were much lower than the results of the empirical force field. It can be seen that integrating physical models into the development of machine learning force field is an important way to improve the accuracy of atomic simulations.

]]> Fe³⁺doped lanthanum nickelate perovskite ceramics were prepared by sol-gel method. Scanning electron microscope锛圫EM锛�, energy dispersive spectrometer锛圗DS锛塧nd diffractometer锛圶RD锛墂ere used to characterize the micro morphology, element distribution and phase of Fe³⁺doped lanthanum nickelate. The electromagnetic parameters of Fe³⁺ doped lanthanum nickel oxide ceramics were measured by using vector network analyzer, the absorption performance was simulated, and the influence of Fe³⁺ doping amount on the absorption mechanism of lanthanum nickel oxide perovskite ceramics was studied. The XRD results indicate that Fe³⁺ ions successfully occupy the lattice position of Ni³⁺ ions, forming perovskite structured ceramics. The SEM results indicate that Fe³⁺ doping has little effect on the particle morphology of LaNiO₃ ceramic material, while the EDS results confirm that the distribution of Fe element in LaNiO₃ ceramic material is uniform and non-agglomerated. In terms of absorption performance, the optimal doping amount of Fe³⁺ doped LaNiO₃ ceramic material is 0.05, with a matching thickness of 1.40 mm and a maximum peak value of 鈥�18.145 dB. The frequency bandwidth below 鈥�10 dB is 1.42 GHz锛�9.38-10.8 GHz锛�.

]]> BN-coated SiC nanofibers锛圫iC_nf锛� reinforced SiC composites were prepared by precursor impregnation pyrolysis锛圥IP锛塸rocess combined with reactive melting infiltration锛圧MI锛塸rocess. Firstly, the h-BN interface was prepared on the surface of SiC_nf using BCl₃ and NH₃ as raw materials by chemical vapor deposition锛圕VD锛塸rocess. Then, the porous SiC_nf/SiC ceramics were prepared by PIP process using polycarbosilane as precursor. The porous ceramics were impregnated with phenolic resin, and the filled carbon was obtained by the pyrolysis of phenolic resin. Finally, the composites were densified by RMI process at 1500 鈩� for 2 hours. The effect of deposition temperature on the microstructure of h-BN and the effect of carbon content on the mechanical properties of the composites were investigated. The samples were characterized by X-ray diffractometer, Fourier transform infrared spectrometer, field emission scanning electron microscopy and universal testing machine. The results show that h-BN can be prepared at 750, 850 鈩� and 950 鈩�. With the increase of temperature, the h-BN interface becomes smooth and compact. The mechanical properties of SiC_nf/SiC composites are improved with the increase of carbon content, the flexural strength and fracture toughness reach the maximum values of 207 MPa and 8.63 MPa路m^1/2 respectively as the carbon content is 19.24%.

]]> Quasi-static axial compression experiments were conducted on the composite thin-walled C-channels with different flange widths. The axial compression failure modes and failure mechanisms were analyzed through CT scanning, and the effects of different flange widths on the axial compression energy-absorption characteristics of C-channels were evaluated by using the energy-absorption indexes. The single-layer shell model and multi-layer shell model of composite C-channel were established, and the finite element models were verified by comparing the failure modes, load-displacement curves and energy-absorption indexes. The results show that the flange width has a significant effect on the axial compression failure modes and energy-absorption characteristics of C-channels. The C-channels with flange widths of 25 mm and 30 mm are failed in the stable and asymptotic manner under the axial compression loads and have good energy-absorption characteristics. The deviation of mean crushing force, energy absorption and specific energy absorption obtained by the multi-layer shell model is within 5%, while that obtained by the single-layer shell model is within 8%, which indicating that the multi-layer shell model of C-channel has the higher simulation accuracy.

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

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