The United States General Electric Company (referred to as GE) has conducted research on SiC_f/SiC composite materials since the 1980s. The successful application and commercialization of GE’s SiC_f/SiC composites in engine systems were achieved after 30 years of continuous investment (nearly 1.5 billion USD) and the collaborative efforts of hundreds of scientists and engineers. This paper details the spiral development history of GE’s prepreg-melt infiltration (MI) SiC_f/SiC composites, focusing on their innovative applications in hot-section components for gas turbines and aero-engines. Through case studies of several critical hot-section components, GE’s research paradigm of “demand traction, technology verification, and engineering iteration”is elucidated. Furthermore, the 10-year progressive design iteration path of the 7FA engine turbine shroud is systematically analyzed, revealing the synergistic optimization logic between service failure feedback and forward design validation. In light of international advancements, this paper interprets GE’s establishment of a“material-process-test”technological barrier through vertical supply chain integration, digital twin-driven process optimization, and machine-learning-based inspection systems. GE’s experience demonstrates that technological breakthroughs require a balance between long-term fundamental research and agile engineering iteration. For domestic development, a closed-loop“design-manufacturing-assessment”research and development process should be established, guided by critical components, alongside multidisciplinary collaboration mechanisms. Additionally, China should strengthen foundational capabilities by leveraging universities and national research and development centers for mechanistic studies, implement multi-dimensional optimization under thermo-mechanical-chemical coupling constraints, accelerate industrial ecosystem construction, integrate fragmented resources, and build rapid“industry-academia-research”verification platforms. A digital transformation strategy encompassing full-chain data acquisition and AI integration is also essential. Finally, by synthesizing successful international practices and adapting them to China’s context, an autonomous development roadmap covering“basic research, pilot verification, standard formulation, and industrial synergy”is proposed, providing methodological guidance for advancing ceramic matrix composite technologies in high-thrust-to-weight-ratio aero-engine applications.

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

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

An investigation is conducted into the mechanisms by which varying levels of phosphorus （P） affect the high-temperature properties, particularly the stress rupture properties, of GH4738 alloy. This is achieved through the use of scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, electron backscatter diffraction（EBSD）analysis, and molecular dynamics simulations. Stress rupture experiments reveals that the optimal stress rupture properties of GH4738 alloy are obtained when the phosphorus content is increased from 0.004%（mass fraction） to 0.0091%. Beyond this range, an increase in phosphorus content lead to a decline in stress rupture properties. Further microstructural analysis and molecular dynamics simulations demonstrates that phosphorus tends to segregate at grain boundaries, enhancing the cohesion force and bonding energy of these boundaries. Additionally, phosphorus interacts with carbides at grain boundaries to influence stress rupture properties. Specifically, as the phosphorus content increases from 0.004% to 0.0091%, M₂₃C₆ carbides at grain boundaries gradually transition from a small, discrete distribution to a discontinuous chain-like distribution. This enhances the pinning effect on dislocations, effectively suppressing their movement and resulting in improved stress rupture properties. However, when the phosphorus content reaches a certain threshold, such as 0.019%, the morphology of M₂₃C₆ carbides at grain boundaries changes to a plate-like shape, leading to a decrease in stress rupture properties.

Optical microscopy（OM） and scanning electron microscopy （SEM） methods are employed to investigate the effect of various load conditions—including a constant load of 200 MPa, an average stress of 200 MPa with a stress amplitude of 130 MPa, and an average stress of 150 MPa with a stress amplitude of 130 MPa—on the microstructural evolution of DZ411 alloy. The experimental findings reveal that the dendrite structure remains relatively unchanged under high temperatures and stress conditions. When compared to a constant load, DZ411 alloy subjected to cyclic loading exhibits a reduced number of interdendritic pores, which are also smaller in size. In the absence of loading, the γ′ phase undergoes rafting to form a sheet-like structure. Notably, cyclic loading exhibits a more pronounced promotion effect on the rafting growth process of the γ′ phase than directional constant loading. Additionally, cyclic loading facilitates the merging and growth of small γ′ phase particles, leading to the formation of longer sheet structures as more γ′ phases become interconnected. Furthermore, under cyclic loading, the size and morphological differences among γ′ phase particles become more pronounced.

Near-α high-temperature titanium alloys typically exhibit poor tensile strengths, falling below 1200 MPa at room temperature and 750 MPa at 600 ℃. On the basis of the cluster formula α-{[Al-Ti₁₂]（AlTi₂）}₁₂+β-{[Al-Ti₁₄]（Mo_0.08Si_0.4Nb_0.1Ta_0.32W_0.14Sn_0.96Zr₁）}₅ of Ti65 alloy, this work partly replaces the elements in the β-Ti structures unit and adds Zr instead of Ti to enhance high-temperature stability of β phase. Consequently, the composition formulas of α-{[Al-Ti₁₂]（AlTi₂）}_x+β-{[Al-Ti₁₃Zr₁]（Mo_0.125Si_0.5Nb_0.125Ta_0.5W_0.25Sn_0.5Zr₁）}_（17–x）（x=11, 12, 13 and 14）series alloys are designed by changing the ratio of α and β cluster unit. The as-cast structure of series alloys is in the form of a basket-weave composed of α plates and residual β phase. As the number of β clusters increases, α plates become increasingly finer, and the tensile strength gradually increases. Among them, the room-temperature tensile strength of Ti-5.3Al-2.5Sn-7.6Zr-0.5Mo-0.5Nb-3.8Ta-0.6Si-1.9W（x=11）reaches 1334 MPa, 28% and 21% more than the reported forged IMI834 and as-cast Ti65 alloys. However, the elongation of this alloy is only 1.3%, which is lower than that of forged IMI834 and as-cast Ti65 alloys. The tensile strength is 856 MPa at 600 ℃, 26% and 37% more than forged IMI834 and as-cast Ti65 alloys with the identical elongation.

ZTA15 titanium alloy ingots, containing oxygen levels of 0.08%, 0.12%, 0.16%, and 0.2%（mass fraction）, are produced through the levitation melting technique. The effect of oxygen content on the microstructure and mechanical properties of the alloy is examined using optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results show that all four ZTA15 structures, varying in oxygen content, are typical Weisberg morphologies. As oxygen content increase, the α-phase bunches shorten and their orientation become more disordered. Furthermore, the widths of the α-slats in the four alloys decrease progressively, measuring 3.92, 3.06, 2.49 μm, and 2.77 μm, respectively. Initially, as oxygen content rose, both tensile and yield strengths of the alloy increase, followed by a decrease, with a concurrent decline in plasticity. Notably, the alloy with 0.16% oxygen demonstrate peak yield and tensile strengths of 1037 MPa and 909 MPa, respectively. However, when oxygen content reach 0.2%, a significant strength reduction is observed, primarily due to the formation of a coarse α-phase structure, resulting in the lowest elongation among the alloys.

This study investigates the thermal cycling behavior of HVOF-MCrAlY combined with APS-nanostructured YSZ（nYSZ） thermal barrier coatings（TBCs） produced using three commercial MCrAlY powders commonly utilized by gas turbine original equipment manufacturers（OEMs） and maintenance, repair, and overhaul（MRO） companies, within a temperature range from ambient to 1150 ℃. Among the coatings, HVOF-A386-2.5+APS-nYSZ exhibits the longest furnace cycle testing（FCT） life, while HVOF-A9624+APS-nYSZ has the shortest. However, the differences in FCT life among the three TBCs are insignificant. All three coatings fails in a manner similar to conventional HVOF-MCrAlY+APS-YSZ（mYSZ） coatings, primarily due to crack propagation and coalescence in the APS-YSZ layer near the YSZ/MCrAlY interface, resulting from interface separation at mYSZ/nYSZ and mYSZ/mYSZ interfaces. The thermally grown oxide（TGO） layer grows fastest on the HVOF-A9624 surface, whereas the growth rate is slowest on the HVOF-A386-2.5 surface. However, the variations in TGO growth rates among the three coatings are relatively small. It is anticipated that increasing the surface roughness of the HVOF-MCrAlY may strengthen the YSZ/MCrAlY interface, thus mitigating crack propagation and coalescence in the TBC. Additionally, reinforcing the YSZ/YSZ interface can enhance resistance to interface separation and surface cracking. Furthermore, controlling the aluminum（Al） content in the MCrAlY and/or doping alloy elements into the MCrAlY may slow down diffusion, reducing the TGO growth rate and preventing excessive formation of mixed oxides. These strategies may collectively contribute to improving the durability of HVOF-MCrAlY+APS-YSZ TBCs under thermal cycling conditions.

Nano-Ag was deposited onto the surface of T-ZnO_w through a process combining dopamine deposition with the chemical reduction of silver, yielding a novel silver-zinc fungicide. The study explored the impact of dopamine deposition duration and silver ammonia solution concentration on the deposition efficacy of nano-Ag, ultimately determining the optimal reaction conditions. The incorporation of this silver-zinc fungicide enhance the antifungal properties of the silicone sealant, without compromising its heat resistance or adhesion. Furthermore, the mold-proof rating of the aged sealant remain at level 1, demonstrating the excellent thermal stability of the T-ZnO_w/PDA/Ag fungicide.

Ceramic matrix composites（CMCs）, as outstanding high-temperature structural materials, have found extensive application in aero engines. Consequently, it is crucial to conduct research on high-temperature mechanical property test methods and ascertain these properties to broaden CMC applications in the aerospace sector. The double-in-plane shear test scheme recommended by the national military standard GJB 10311—2021 often results in high calculated average shear stress in the gauge area due to stress concentration at the incision, leading to significant deviations between in-plane shear modulus test results and those of the V-notch shear test. To address this, a novel in-plane shear mechanical property test method has been developed by integrating the digital image correlation method（DIC） with the double-incision shear test. Compared to the V-notch shear test, this method boasts a smaller test fixture and specimen size, making it more suitable for high-temperature in-plane shear testing. To mitigate the impact of stress concentration at the incision, finite element model updating（FEMU） is proposed, constructing an objective function based on the variance between the average in-plane shear strain and numerically calculated strain in the DIC-measured gauge area. This allows for iterative determination of the material’s in-plane shear modulus. For engineering application convenience, the material’s in-plane shear modulus and strength can be obtained by varying the specimen’s incision depth during testing. The feasibility of this test method and the reliability of its results are further validated using SiC/SiC orthogonal laminated ceramic matrix composites. Results indicate that the proposed experimental method can simultaneously determine the in-plane shear modulus and strength of CMCs. The SiC/SiC ceramic matrix composites exhibit typical yield points in their in-plane shear stress-strain behavior, with post-yield shear behavior characterized by linear strain strengthening.

Fatigue tests were conducted on FGH96 flat plates containing a hole at 600 ℃. Utilizing a viscoplastic constitutive model, the stress and plastic strain distributions within these plates were meticulously calculated. Scanning electron microscopy（SEM） was employed to analyze the fatigue failure mechanism. Based on SEM observations and the geometric attributes of the FGH96 plates with holes, the critical fatigue damage and stress concentration coefficient were defined. Subsequently, the CDM（cumulative damage model）was refined accordingly. The findings revealed that, in comparison to conventional fatigue life prediction techniques, the revised CDM model, which incorporates critical fatigue damage and stress concentration coefficients, exhibited enhanced prediction accuracy for the fatigue life of FGH96 flat plates with holes. Notably, all prediction results fell within a ±2 error band.

To address the very high cycle fatigue（VHCF）issue of GH4169 nickel-based superalloy, which is widely utilized in aero-engines, a fatigue specimen subjected to 20 kHz ultrahigh frequency vibration is designed and tested utilizing a piezoelectric ultrasonic fatigue testing system. At room temperature, the P-S-N curves for VHCF of GH4169 nickel-based superalloy are obtained under various survival probabilities of 5%, 50%, and 95%. The experimental findings reveal that the GH4169 material’s curve exhibits a downward trend when the fatigue life attains 10⁷ cycles, indicating the absence of a fatigue limit and the persistence of fatigue failure. Fracture analysis results indicate that the majority of VHCF cracks initiate from the surface or subsurface of the specimen, with both single-source and multi-source cracking observed. The cracking modes encompass surface sliding cracking and non-metallic inclusion-induced sliding cracking.