- 中国科学引文数据库(CSCD)核心期刊
- 中国核心期刊
- 文摘与引文数据库(Scopus)
- 剑桥科学文摘(CSA)
- 英国INSPEC数据库
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.
High-energy photons in space environments, such as X-rays, thermal neutrons, and gamma rays, can cause ionization in polymer materials, leading to covalent bond breakage and degradation reactions. These reactions result in effects such as embrittlement, loss of elasticity, flaking, softening and stickiness, loss of mechanical strength, and gas emission, which can cause temporary damage or permanent failure of aerospace materials or devices. Rare earth elements have excellent radiation resistance to neutrons, high-energy photons and gamma rays due to their high absorption cross sections and atomic numbers. The photoelectric effect, Compton effect and electron pair effect of rare earth elements are firstly introduced in this paper. Next, the domestic and international research progress on the radiation resistance of rare earth elements in polymer materials, including fibers, plastics, rubber, epoxy resins, polyvinyl alcohol (PVA), and chitosan are reviewed. The discussion covers the incorporation of rare earth elements through doping, nanomaterial formation, and organic salts, utilizing preparation techniques such as co-precipitation synthesis, copolymerization, blending and extrusion, and molding. Testing methods include cobalt irradiation, neutron radiation, Monte Carlo simulations, and MCNP program calculations for neutron shielding. Comparative results with heavy metal lead demonstrate that rare earth elements significantly enhance the radiation resistance of polymer materials. Given their non-toxic and lightweight advantages, rare earth elements are expected to replace heavy metals like lead in applications within the medical, nuclear, and aerospace industries. The paper also provides a forward-looking perspective on the development of rare earth-based radiation-resistant polymer composite shielding materials in space environments.
Grain refinement plays an important role to enhance the mechanical properties of magnesium alloys. In this work, graphene-reinforced AZ91 composites were successfully prepared by pre-dispersion combined with gravity casting method. The microstructure of the GNP/AZ91 composites was characterized using OM, SEM, TEM, etc. The results show that the grain size of AZ91 alloy gradually decreases with the increase of GNP content. When 1% GNP is added, the grain size of AZ91 alloy is reduced from 415 μm to 86 μm, with the refinement efficiency of 79%. It is found and revealed through TEM observation that the refining mechanism of GNP on AZ91 alloy is mainly Al4C3 phase obtained by in-situ reaction of GNP with Al element in AZ91 melt, which can promote the heterogeneous nucleation of α-Mg grains, thus achieving significant grain refinement effect. When the GNP content is increased to 0.5%, the best mechanical properties are obtained for AZ91 alloy with the UTS, YS and EL reaching 150, 96 MPa and 2.1%, the improvement of 34%, 32% and 91% respectively compared to AZ91 alloy.
The objective of this work is to investigate the effects of pre-exposure on the CMAS corrosion behavior of doped and modified Gd2O3-Yb2O3-Y2O3（GYb-YSZ） thermal barrier coatings. Three types of test, such as high-temperature pre-exposure test, CMAS corrosion test, and CMAS corrosion test after high-temperature pre-exposure, are conducted by preparing standard specimens. The changes in microstructure and basic mechanical properties of the coatings after these types of test are comparatively studied using scanning electron microscopy（SEM） and nano indentation, thereby discussing the impact of pre-exposure on CMAS corrosion. The results show that short-term pre-exposure treatment leads to multi-channel penetration, while long-term pre-exposure treatment results in the occurrence of longitudinal through-cracks. Pre-exposure to 980 ℃ or 1050 ℃ for 125 h reduces the penetration effect of CMAS. When the temperature reaches 1150 ℃, CMAS penetrates the top coat in the molten state. In the process of cooling, CMAS re-solidification causes to form vertical cracks resulting from the expansion of columnar grain boundaries, extending through the top coat, and accelerating the spallation of the coating. Meanwhile, after CMAS corrosion, the coating shows a significant increase in Young’s modulus of 48% and hardness of 50% compared to the original sample. Thus, the specimens exhibit significant resistance to CMAS corrosion under pre-exposure treatment at 980 ℃ or 1050 ℃ for 125 h.
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 550HV0.2, 1120HV0.2 , 534HV0.01 and 307HV0.2, 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.
Corrosion problem resulting from alternating ambient salt spray and high temperature oxidation poses a great threat to the safe service of aircraft engine during frequent start-stop in marine environment. In the present study, Ni25Cr5AlY coating is prepared on top of GH4169 superalloy substrate by direct-current（DC） magnetron sputtering. Corrosion behavior of the Ni25Cr5AlY coating is systematically studied by designing three different test conditions: high temperature oxidation at 1000 ℃, ambient salt spray, and alternating ambient salt spray and high temperature oxidation. The phase constitution and morphology of the corrosion products are analyzed by X-ray diffraction（XRD） and scanning electron microscopy（SEM）. The results indicate that after 168 h oxidation at 1000 ℃, the coating forms a dense and continuous Al2O3 scale which resists well against the oxidizing environment, while the coating suffers from pitting locally after 168 h salt spray test. After 168 h exposure to alternating ambient salt spray and high temperature oxidation test, the Al2O3 scale formed on the coating is damaged owing to the chlorine induced active oxidation mechanism, eventually resulting in Cr2O3 scale formation. In addition, the Cr2O3 scale is porous and cracks locally, which causes accelerated corrosion of the coating and internal oxidation of the coating and substrate. The corrosion degradation of the coating is accelerated under the synergistic effect of salt spray and high temperature oxidation. The GH4169 superalloy without the coating experiences severe scale spallation after 168 h exposure to the alternating test, featured by forming a poorly protective NiO scale with prevalent internal oxidation.
Short beam shear tests conbined with digital image correlation were carried out for thick-section glass fiber reinforced resin matrix composites, and the variation of interlaminar shear behavior of unidirectional composites with different thicknesses with thickness was obtained. In order to explore the size effect mechanism of interlaminar shear mechanical behavior of materials, the microscopic characteristics of pores of samples with different thicknesses were observed through scanning electron microscope photos of sample slices. Image processing was used to obtain the contours of irregular pores, and parameters for quantitative characterization of microscopic characteristics were proposed. A three-dimensional representative volume element（RVE）model containing fibers, matrix, fiber/matrix interface and pores was randomly generated, and the effect of irregular pores of different sizes and distributions on the interlaminar shear strength of composites was studied by numerical analysis. The results of short beam shear tests showed that the interlaminar shear mechanical behavior of unidirectional composites was independent of the thickness of the specimens, but the shear strength decreased with the increase of the thickness of the specimens. The image analysis results showed that the distribution law, size, concentration and irregularity of the pores in samples of different thicknesses were significantly different. The numerical analysis results of RVE showed that the damage was caused by the destruction of the fiber-matrix interface close to the pores, and the interlaminar shear strength of thick-section composites decreased with the increase of the maximum pore size under the same porosity. At the same time, pore concentration and porosity also have a significant effect on the interlaminar shear strength of the material. The above experimental and analytical results show that the size effect of the interlaminar shear strength of thick-section composite materials is related to the microscopic characteristic parameters of the material pores. As the thickness of the composite material increases, the porosity, maximum pore size and concentration increase, and the shear strength decreases. Therefore, the difference in the microscopic characteristics of pores in materials of different thicknesses is one of the important mechanisms that lead to the decrease in the interlaminar shear strength of the material.
With the U-shaped leading edge made of aramid laminate as the focus of this study, we have developed models for both the curing temperature field and the curing deformation field, aiming to unravel the underlying mechanisms of its curing deformation. Our investigation delves into the various influence patterns of core materials, the sequence of the inner skin laying-up, and the structure of the leading edge on the overall curing deformation of the component. The findings reveal that rigid foam characterized by a high elastic modulus effectively supports the inner skin under curing pressure, thereby minimizing internal defects and curing deformation within the core material. Compared with the core material, the sequence of the inner skin laying-up and the design of the leading edge structure exert a more profound influence on the curing deformation of the component. Taking into account the post-curing neck-in and torsional deformation stemming from the component’s asymmetry, we have found that employing the [0/45/−45/0/0/0/45] laying-up sequence for the inner skin achieves minimal curing deformation.
Flax fiber/epoxy composites have attracted extensive attention in aviation applications due to the advantages of low density, remarkable mechanical properties and environmental friendliness. However, the interface compatibility between hydrophilic flax fiber and hydrophobic epoxy resin matrix is poor, which makes the lamination resistance of the composite insufficient, and affects the bearing capacity and service life of the material. Chopped fiber interlaminar toughening is an effective method to improve the interlaminar fracture toughness of composites. Besides, the numerical simulation based on cohesive zone models has also become an effective tool for analyzing interlaminar toughening in the composites. In this study, three different cohesive zone models, including bilinear, exponential and trilinear cohesive zone laws, are used to simulate the mode Ⅰ interlaminar fracture behavior of chopped aramid fiber interleaved flax fiber/epoxy composites. The numerical results are analyzed and compared with the double cantilever beam（DCB）experimental results and digital image correlation（DIC）observations, summarizing the influence of different cohesive zone laws. The results show that bilinear and exponential cohesive zone models are unsuitable for simulating the interlaminar toughening effect of chopped fiber interleave due to the numerical results with no laddered or fluctuated descent. The trilinear cohesive zone model can effectively present the chopped fiber interlaminar toughening effect and behavior by including the toughening effects of fiber bridging and matrix failure so that fiber bridging failure mode and crack propagation behavior are similar to those observed with the DIC method. This research provides a rational basis for the chopped fiber interlaminar toughening design of flax fiber/epoxy composites.
Ultrahigh strength steel has been widely used to manufacture aircraft landing gear and other load-bearing structures, which is prone to corrosion fatigue failure when serving in harsh marine environment. The fatigue crack propagation behavior of small-sized samples in laboratory is different from that of actual structures due to constraint effect. The fatigue crack propagation tests of A100 ultra-high strength steel in air, neutral and acidic seawater are carried out using single edge tension specimens with different crack depths and specimen thickness. The results show that with the increase of crack depth and sample thickness, the constraint level of crack tip increases, the fatigue crack growth resistance decreases, and the crack growth rate accelerates. The combined effect of constrains and corrosion environment significantly accelerate the fatigue crack growth rate of A100 ultrahigh strength steel. As the amplitude of stress intensity factor ΔK equals to 30 MPa·m1/2, a good positive correlation between constraint parameters and corrosion fatigue crack growth rate can be observed. The relevant research results can provide reference for the service life assessment of ultrahigh strength steel structures in marine environment.
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.
To address the challenges posed by the time-consuming nature of fatigue test and the scattered nature of test data, it is evident that P-S-N curves derived from small samples with high survival rates lack sufficient accuracy, leading to unreliable predictions of fatigue life. The data fusion method based on the performance-life probability mapping principle is used to fuse small sample fatigue data of different stress levels, and the feasibility of obtaining accurate P-S-N curves by this method is analyzed and evaluated. The results demonstrated that P-S-N curves obtained post-fusion are closer to the P-S-N curve derived from larger sample datasets. This approach effectively enhances both reliability and accuracy in predicting fatigue life while simultaneously reducing the amount of required fatigue tests. A comparative evaluation is conducted on the predictive capabilities for fatigue life before and after fusion using different models; notably, it is found that the three-parameter power function model demonstrates superior predictive ability, whereas when ample fatigue data is available, the prediction capabilities among four models（Basquin S-N model, exponential S-N model, three-parameter power function S-N model（based on lognormal distribution）, and three-parameter power function S-N model（based on three-parameter Weibull distribution） exhibit a considerable degree of resemblance.
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Founded in 1981 (Bimonthly) ISSN 1005-5053 CN 11-3159/V Sponsored by Chinese Society of Aeronautics and Astronautics & AECC Beijing Institute of Aeronautical Materials |
