Beryllium–aluminum alloy is expected to become a key material for the lightweight of China’s new generation of aerospace equipment due to its excellent properties such as light weight, high specific stiffness and high specific strength. However, beryllium and aluminum have low solid solubility at room temperature and do not form intermetallic compound, resulting in poor interface bonding, which become the key to restrict improvement of the strength and plasticity of beryllium–aluminum alloy. In this paper, research status of the interface structure regulation of beryllium–aluminum alloys is reviewed, including the structural characteristics of the beryllium–aluminum interface, morphology of the beryllium phase, regulation of BeO, and alloying of the matrix. This paper focuses on the research progress of matrix alloying composition design to regulate the beryllium–aluminum interface structure, expecting to provide reference for the research on material composition design optimization and performance improvement of beryllium–aluminum alloys and other similar systems.

Poly(p-phenylene benzobisoxazole) (PBO) fibers, due to their high strength, high modulus and excellent mechanical properties, have become one of the most promising reinforcing materials for resin matrix composites; however, their dense and smooth surfaces and high inertness of the chemical structure lead to poor interfacial strength between the fibers and the matrix, which seriously restricts the performance of the composites. Therefore, it is important to regulate the interfacial properties between PBO fibers and resin matrix. This paper expounds how the physical and chemical changes on the fiber surface contribute to the adhesion strengthening mechanism at the interface. The research progress of interfacial modification techniques for PBO fiber composites in recent years is systematically introduced. Moreover, typical composite interfacial models and their mechanisms are introduced to provide theoretical basis and new ideas for the evaluation and modification methods of the interfacial properties of composites.

Carbon nanomaterials (graphene and carbon nanotubes) possessing excellent mechanical properties, outstanding thermodynamic stability, and superior electrical conductivity, are regarded as the ideal reinforcement for metal matrix composites. The employment of carbon nanomaterials in the magnesium alloy composites help to overcome the low strength, hardness, and modulus of magnesium alloys. However, due to the paucity of chemical reactions between magnesium and carbon nanomaterials and their poor wettability, the interfacial strength between the two materials is weak, thereby limiting the performance of the reinforcement. The utilization of interfacial regulatory substances is a conventional approach to enhancing the bonding strength at the interface of composite materials. This paper mainly introduces the preparation methods and types of interfacial regulatory materials for carbon nanomaterials reinforced magnesium matrix composites; focuses on the methods of adding interfacial regulatory substances to the composites, the interfacial bonding of interfacial regulatory substances to reinforcement and matrix, and the mechanism of improving the interfacial bonding strength of the composite materials.

Superalloys with high strength and large consumption are one of the vital materials for advanced aeroengines. However, its high density limits weight reduction and efficiency improvement of the aero-engines. Therefore, how to reduce weight of the superalloy component and improve efficiency of the engine is the research key point for new lightweight & high temperature-resistant structural materials. SiC fiber reinforced superalloy matrix composites show attractive potential in weight savings and have promising applications in aerospace industry. The severe interface reaction between the fiber and superalloy is an unresolved issue in the manufacturing process of superalloy matrix composites. In order to improve the interfacial compatibility between the superalloy and fiber, the common method is to introduce a diffusion barrier layer between the two. However, barrier coatings are prone to fracture during the densification process, and the protective effect of which is weakened then. Thus multi-component construction as an effective compromising method is introduced; it reduces the amount of interfaces and prevents fibers from eroding. From the perspective of research progress of SiC fiber reinforced superalloy composites, issues regarding the interface of the composites are discussed, improving method are summarized, and interface design are analyzed and expounded.

In this paper, the high-strength titanium alloy skeleton structure was prepared by laser selective melting (SLM). Titanium–aluminum composite with different thickness and crystal morphology was formed by smelting the filled aluminum powder/bulk. It was found that diffusion reaction occurred between the interface of Ti–6Al–4V strengthening skeleton and Al–Mg–Sr–Zr alloy matrix, forming a dense metallurgical bonding. The precipitated phases in the interface were mainly TiAl₃, TiAl, TiAl₂ and Ti₃Al₅. With the increase of smelting temperature and holding time, thickness of the interface reaction layer gradually increased, reaching 600 μm at 800 ℃–1 h, which proves strong bonding of the composite structure interface. The elastic modulus of the reinforced skeleton, aluminum alloy matrix and reaction interface was analyzed. It was found that the elastic modulus of the reaction layer (1.2×10¹¹ Pa) was higher than that of the titanium alloy reinforced skeleton (1.07×10¹¹ Pa) and the aluminum alloy matrix (7.1×10¹⁰ Pa). The results provide theoretical basis for the spatial controllable strengthening of aluminum alloys, which is expected to overcome the inverse relationship between strength and toughness of traditional materials.

Ti/Mg bimetal composites possess the advantages of light weight and high strength, making them highly promising for various applications in lightweight field. This study enhanced the interface bonding of the TC4/AZ91D bimetal composite through fabrication of a pyramidal lattice structure on the TC4 surface. The lattice structure exhibited a high porosity and rough surface, which strengthened the interface bonding of the liquid–solid compound casting TC4/AZ91D. Finite element orthogonal analysis results indicated that the influential order of the lattice structure parameters is aspect ratio > inclined angle > node-to-strut diameter ratio. The optimal lattice structure parameters (within rod diameter range of 0.5–2 mm) were determined to be rod diameter d_s=1.7 mm, aspect ratio (l/d_s) of 5.5, inclined angle ω of 52°, and node-to-strut diameter ratio (d_n/d_s) of 2.2. Experimental verification showed a trend of increasing and then decreasing of bonding strength of the bimetal with an increasing of l/d_s. Under the optimal lattice structure parameters, bonding strength of the bimetal reached 91 MPa. Analysis of interfacial wettability revealed that the rough textured surface of the additively manufactured TC4 lattice structure enhanced the wettability between TC4 and AZ91D, resulting in a serrated interface structure, thus strengthened the mechanical bonding at the interface.

Pyrolytic carbon (PyC) interphase is a vital constituent of Cf/SiC composite and a key factor influencing mechanical properties of materials. PyC interphases with different microstructures have different intrinsic properties and performances, which would be beneficial to adjusting the mechanical properties of C_f/SiC composites. To precisely control texture type of the PyC interphase, 9 groups of PyC interphases with low, medium, and high textures were designed and prepared in this study. Utilizing the DETCHEM software, the pyrolysis components and their contents of the precursor gas source (methane) under the 9 sets of different chemical vapor deposition (CVD) parameters were calculated, and the key parameter R' that determines the texture type of PyC interphase was identified. When R' of the pyrolysis component of methane is ≥ 22, it tends to deposite a low-texture PyC interphase; when R' ≤ 8.1, a high-texture PyC interphase is favored; when R' falls between 8.1 and 22, a medium-texture PyC interphase is formed. Furthermore, the CVD parameter range for different texture types of PyC interphases, PyC texture phase diagram are obtained, and growth models for different texture types of PyC interphases are constructed.

Carbon/metal composites are ideal thermal management materials, valued for their excellent thermal properties and high designability. Firstly, given the prevalent issues of poor interfacial bonding and high thermal resistance at interfaces of carbon/metal composites, this review examines various interfacial modification techniques. The impact of such modifications on the bonding strength at the composite interfaces is analyzed from two specific perspectives: matrix alloying and coating of reinforcement. Secondly, the current methodologies for analyzing interfacial thermal resistance are summarized, encompassing theoretical calculations, simulations, and experimental testing. Finally, future research directions for carbon/metal composites are identified, focusing on the testing of interfacial thermal resistance, analysis of heat transfer mechanisms at the interface, and the design and control of interface layers.

Thermal mismatch and thermal oxidation stress caused by generation of thermally grown oxide (TGO) in thermal barrier coatings (TBCs) are the main reasons for spalling failure of ceramic coating. Most terahertz time-domain spectroscopy methods have trouble correctly measuring early TGO thickness due to the significant absorption of porous ceramic material to terahertz radiation, external noise, and system oscillation. Therefore, a sparse decomposition-based TGO thickness calculation method through terahertz technique is proposed. A complete atom library is structured based on the characteristics of the terahertz pulse and noise signal. The best atom is searched in the atomic library, and the signal is decomposed and reconstructed. On this basis, the increment of time-of-flight of signal is computed to determine the TGO thickness. The results verified the proposed method can accurately calculate the thickness of naturally grown TGO in TBCs, with an absolute error of 0.28 μm, meeting the requirement of practical engineering application.

Al–Mg–Sc–Zr fatigue samples were formed by selective laser melting to study the characteristics of pore defects and effect of pore defects on fatigue properties of aluminum alloy by laser additive manufacturing. The threedimensional characteristics of pore defects in fatigue samples were characterized by X-ray computed tomography (X-CT), and the number, size and morphology of pore defects were statistically analyzed. The fatigue properties of alloy were tested by fatigue test and fatigue fracture morphology was observed. The results show that pore defects mainly comprise of porosity and lack of fusion (LOF), in which, the LOF defects are large in size, irregular in shape and mostly flat interlayer unfused defects. The porosity of fatigue samples ranges from 0.004% to 0.102%; the large-size pore defects (with an equivalent diameter >100 μm) account for 0.58% of the total pore defects; the maximum equivalent diameter is 188 μm. The degree of sphericity (DOS) of pore defects is between 0.2 and 0.6 with DOS of large-size pore defects less than 0.4. Fatigue fracture morphology shows that the fatigue cracks originated from LOF defects of the sample surface, moreover, the larger the feature size of the crack source defects, the lower the fatigue life of the sample.

There are multiple rotary axes in the helicopter transmission system and their spatial pose information is an important basis for subsequent assembly. Traditional measurement methods have low accuracy and slow speed, and are difficult to realize digitalization. Aiming at the above problems, a machine vision-based rotation axis calibration method for helicopter transmission system is proposed. Firstly, the absolute coordinate system is established by the visual target, and the sub-pixel corner is detected by the checkerboard corner detection technology based on Radon transform. Then the absolute pose of the monocular camera is estimated by the Levenberg–Marquadt algorithm. Finally, the spatial pose information of the rotary axis is obtained by fitting the motion trajectory of monocular camera. Experimental results show that the calibration accuracy of this method is higher than 0.35 mm, which meets the requirements of subsequent transmission system assembly.

Aiming at the requirements of the thickness-controllable processing for the integral bottom of the launch vehicle tank, the mirror milling process was studied from the aspects of cutting force suppression and stability control. Through the milling force simulation analysis, the relationship between mirror milling process parameters and milling force was studied. The principle of selecting process parameters was proposed to ensure material removal rate by feed and cutting width and to control the cutting force by reducing the cutting depth. A method was proposed to measure the machining stability by compensating the axis fluctuation of the inner support and the influence of jet pressure of the inner support was studied. Taking the integral bottom of the new-generation launch vehicle as object, the process flow was designed, and the mirror milling path planning and post-processing were studied. Through processing of the integral bottom product, the thickness accuracy of 0.3 mm and maximum profile deformation of 3.2 mm were achieved, which effectively verified the processing capacity and effectiveness of the mirror milling process.