- Ei，ESCI收录期刊
- 中国科学引文数据库(CSCD)核心期刊
- 中文核心期刊
- 文摘与引文数据库(Scopus)
- 剑桥科学文摘(CSA)
As the turbine inlet temperature in aero-engines continues to rise， conventional thermal barrier coatings （TBCs） are becoming increasingly ineffective at blocking thermal radiation in the near-infrared wavelength range generated by high-temperature gases. The heat transfer of heat radiation can penetrate through the coating and directly heat the underlying metal substrate， thereby compromising the service life of hot-end components. In this paper， the authors’ experimental results are used to review recent developments in the design of novel TBCs materials and structures that combine thermal insulation with enhanced radiation suppression capabilities. A comparative analysis of the near-infrared optical properties of conventional TBCs is presented. The current methods aimed at improving the ability of coatings to mitigate radiative heat transfer are discussed. Particular attention is given to the issue of conventional YSZ-based inability of TBCs to effectively block infrared radiation in the shortwave infrared region. An analysis is conducted on the two fundamental approaches for reducing the infrared transmittance of TBCs， namely， improving the infrared reflectance or infrared absorptance of coatings. Additionally， a systematic summary of the strategies for tuning the infrared reflectance and absorptance of coatings， including influencing factors， underlying mechanisms， advantages， and limitations， is provided. Finally， future trends and breakthrough directions in the development of novel radiation-suppressing coatings， particularly in terms of material and structural design as well as the use of high-performance computational tools， are highlighted.
Continuous fiber-reinforced ceramic matrix composites have been widely used in aerospace， defense industry， emerging civilian，and other fields due to their excellent properties such as low density， high strength and high temperature resistance. However， most of the preparation processes of continuous fiber-reinforced ceramic matrix composites have problems such as high cost and long cycles， which limit the application and promotion of ceramic matrix composites. The development of a low-cost preparation process is the key to promoting the wide application of continuous fiber-reinforced ceramic matrix composites. In this paper， the preparation process of continuous fiber-reinforced ceramic matrix composites is briefly introduced， and the research status of low-cost processes such as reactive melt infiltration， nano infiltration and transient eutectoid， and slurry infiltration and hot pressing is summarized. The optimization of preparation process， microstructure and properties of composites is reviewed， and the future research direction of the low-cost preparation process is proposed， such as the preparation of ultra-high temperature ceramic interface by molten salt method and the preparation of porous matrix with uniform pore structure by reaction-induced phase separation， which can significantly improve the comprehensive properties of continuous fiber-reinforced ceramic matrix composites.
The excellent comprehensive high-temperature performance of Ti2AlNb alloy makes it a potential substitute for some nickel-based alloys， serving as a key structural material for weight reduction in aviation engines. In response to the lightweight design requirements of future high-performance aviation engines， a combination of statistical comparison， control experiments， finite element simulation analysis， and other methods are used to analyse the material properties， alloy cold/hot processing performance， weight reduction benefits， etc. The advantages， potential， and remaining issues of the alloy’s application in aviation engines are discussed. The analysis results indicate the feasibility of using Ti2AlNb alloy in aviation engines， with significant advantages in weight reduction： the alloy achieves a good balance of strength， toughness， and plasticity without obvious shortcomings； it has acceptable cold and hot processing performance， and can obtain engineering-sized parts through deformation， casting， and other methods； its combustion resistance is superior to traditional titanium alloys； when applied to static components such as casings， it can achieve a weight reduction of 35.3% compared to high-temperature alloys， and when applied to integral blade/disks and rotor components， it can achieve a weight reduction of 37.3% compared to nickel-based high-temperature alloys.
Infrared radiation at the hot-section of the aero engine is easily detected by infrared detectors， which is not conducive to aircraft service in a complex monitoring environment. How to reduce the infrared radiation characteristics of high-temperature parts of aero engine and improve the high-temperature infrared stealth performance of the aero engine is a difficult problem that needs to be solved. This paper discusses the infrared stealth mechanisms and research status of metal-based， inorganic non-metallic， and structural infrared stealth materials with potential applications in high-temperature environments. It also highlights the future development trends for high-temperature infrared stealth materials， including the need for further investigation into the failure mechanisms of these materials， the integration of temperature control methods to meet higher-temperature stealth requirements， and the necessity to develop comprehensive stealth performance to ensure the capability of aircraft to remain stealthy in complex environments.
The microstructure and thin-walled effect of different samples （double-wall ultra-cooling turbine blades， combined cooling turbine blades， investment casting thin-walled specimen， and round bar specimen） of the third-generation single crystal superalloy DD9 are investigated by optical microscope， field emission scanning electron microscope， and electron probe apparatus. The results show that there are differences in the microstructures of the four specimens. When the section sizes are the same， the as-cast primary dendrite arm spacing， the sizes of γ′ phases， and the dendrite segregation of the as-cast and heat- treated specimens of DD9 single crystal turbine blades are all larger than those of the investment casting thin-walled specimens. After full heat treatment， the sizes of the γ′ phases of single crystal turbine blades with the same cross-sectional size are similar to those of investment casting thin-walled specimens. The as-cast primary dendrite arm spacing， the sizes of γ′ phases， and the dendrite segregation of the as-cast and heat-treated thin-walled specimens of DD9 alloy all decrease with the decrease of the cross-sectional size.
To investigate the effects of aluminizing coating on the surface integrity and rotational bending high cycle fatigue performance of DD6 alloy， the chemical vapor deposition method is used to aluminize DD6 fatigue samples after standard heat treatment. The cross-sectional microstructure and elemental distribution of DD6 alloy samples with aluminizing coating are analyzed using SEM and EDS， and the high cycle fatigue properties of the uncoated and coated samples are tested at 760 ℃ and 980 ℃， respectively. The results show that the surface area of the sample with aluminizing coating is mainly divided into two layers： inner and outer. The outer layer is mainly composed of the β-NiAl phase， and the inner layer is a diffusion layer， containing many solid solution strengthening elements. The aluminizing coating can slightly reduce the rotational bending high cycle fatigue performance of the alloy at 760 ℃ and 980 ℃ and has a significant impact on the fatigue life in the high-stress amplitude region and a small impact on the low-stress amplitude region. The coupling effect of surface roughness， oxidation damage， and element interdiffusion is the fundamental reason for the difference in fatigue life between uncoated and coated samples.
GH4065A is a newly developed high-performance cast-wrought Ni-base superalloy with ultra-low C and N content used for advanced turbine engine disc. In this study， the alloy’s inclusions of the alloy are characterized and statistically analyzed. To investigate the fatigue fracture mechanism， strain-controlled fatigue tests are conducted at 400 ℃ and 650 ℃ on the fine-grained and coarse-grained samples respectively. The results show that the alloy’s inclusions of the alloy are mainly nitrides. For the fine-grained samples， discrete nitride particles and clustered nitrides both with a critical size larger than the average grain size are responsible for the fatigue crack initiation. When subjected to high-level strains （≥0.9%）， fatigue failure primarily originates from surface nitrides， with rare occurrences of boride and oxide initiation. Surface crack induced by Al2O3， rather than boride or MgSiO3， is found to significantly reduce the fatigue life. Higher fatigue temperature results in reduced life cycles. When under lower levels of strain， however， subsurface/internal nitride-facet initiations dominate and fatigue life is prolonged by the elevated temperature. In the coarse-grained samples， fatigue failures at 400 ℃ are found to be initiated by quasi-cleavage cracking mechanism. Due to the increased grain size， the inclusion-induced crack initiation is suppressed while slip-induced cleavage cracking mechanism becomes predominant.
The SiC-BN/SiOC ceramic matrix composites are prepared through the precursor infiltration pyrolysis（PIP） process， using wave-absorbing SiC fibers with in-situ BN coatings as reinforcements and SiOC ceramic as the matrix. After 7 PIP preparation cycles， the composite achieves densification with density of 2.05 g/cm³ and porosity of 4.28%. The dielectric constants are tested with vector network analyzer. Using transmission line theory， the microwave-absorbing properties of the composites from room temperature to 800 ℃ at 8.2-18 GHz are optimized. The results show that the dielectric constants of the SiC-BN/SiOC composites exhibits significant frequency dispersion effects， leading to broadband microwave-absorbing properties. When the thickness of the composites is 2.1 mm， the maximum bandwidth of the reflection loss better than -10 dB in the X band and the Ku band is 5.7 GHz. As the ambient temperature increases， the real and imaginary parts of the complex permittivity of the composites both increase. For reflection loss better than -5 dB in a wide bandwidth， the optimum thicknesses decrease from 2.3 mm （200 ℃） to 1.1 mm （800 ℃）.
K439B is a new type of nickel-based superalloy with a service temperature up to 800 ℃. In the face of the demand for mass reduction of aircraft， the structure of its components is developing in the direction of thin-wall. Thus， it is necessary to study the microstructure of the K439B alloy thin-walled castings. For this purpose， the thin-wall castings with wall thicknesses of 1 mm and 2 mm are designed， and gravity investment casting experiments and numerical simulations are conducted. Comparative analysis of the as-cast microstructure of the castings shows that the growth directions of the dendrites in both 1 mm and 2 mm thin-wall are along the shell wall pointing to the center， the difference is that the growth directions of the dendrites in the 1 mm thin-wall are closer to the vertical angle with the wall. The average primary dendrite arm spacings （PDAS） are 60.64 μm for 1 mm thin-wall and 46.23 μm for 2 mm thin-wall， respectively. The average secondary dendrite arm spacings （SDAS） are 19.31 μm for 1 mm thin-wall and 22.69 μm for 2 mm thin-wall， separately. Meanwhile， the average grain size of the 1 mm thin-wall is 216.61 μm， and the corresponding size of the 2 mm thin-wall is 239.11 μm. Combined with numerical simulation analysis， it is shown that the relationship trend between dendrite arm spacings， temperature gradient， and cooling rate basically matches the existing empirical formula， but the relationship between PDAS and temperature gradient and cooling rate no longer simply matches the formula when the wall thickness is reduced to a certain critical thickness. These results of the experimental and simulation analysis could provide a reference to rationally design the casting process for the K439B nickel-based superalloy thin-walled casting crafts.
To clarify the evolution of the interfacial microstructure of GH4065A superalloy during plastic deformation bonding， the GH4065A superalloy is bonded under temperatures of 1050-1110 ℃ with the pressure of 20-40 MPa and a time range of 20-35 min. OM，SEM， and EBSD were employed to characterize the special positions between bonding regions and unbinding regions to investigate further the influence of plastic deformation bonding parameters（bonding temperature，holding time，and bonding pressure） on the microstructural evolution of the interface.This study focuses on the nucleation of new recrystallization grains in the bonding area and the healing of the original interface. The results show that increasing the bonding temperature， pressure and the holding time will facilitate the healing of the interface. but at the same time， it will also prompte the coarsening of the grains simultaneously. The joint obtained under 1080 ℃，30 MPa，30 min has uniform microstructure and no obvious defects， exhibiting an excellent metallurgical bonding effect.The results of EBSD show that the discontinuous dynamic recrystallization characterized by strain-induced grain boundary bulging is the dominant mechanism， and continuous dynamic recrystallization characterized by subgrain progressive rotation occurs in the bonding process. Moreover， the dynamic recrystallization（DRX）nuclei will grow toward the interface with ongoing deformation， contributing to the healing of the original interface.The metallurgical bonding caused by plastic deformation bonding mainly experiences three stages： initial contact， nucleation and grain growth， and joint formation.
This study focuses on the single crystal （SC） superalloys CMSX-4 and DD5， designing and fabricating a SC test plate casting with five distinct stages. Castings with the same crystal orientation are selected to investigate their recrystallization （RX） behavior after solution heat treatment at 1300 ℃ for 2 h and 1310 ℃ for 4 h. The results indicate that CMSX-4 exhibits a stronger tendency for RX compared to DD5. Following a solution heat treatment at 1300 ℃， the CMSX-4 SC test plate displayed RX at the lower corners of 2-5 stage platforms， with the extent of RX expanding as the solution heat treatment temperature rose. Conversely， no RX was detected in the DD5 SC test plate post-treatment at 1300 ℃. Elevating the solution temperature to 1310 ℃ results in only a minor area of RX on the outer platform of the fourth stage in the DD5 SC test plate. The micro-shrinkage porosity and eutectic content of the as-cast and solution heat treated CMSX-4 alloy are both higher than those of the DD5 alloy. The higher content of eutectic and micro-shrinkage porosity provides more nucleation sites and quantities for RX in the CMSX-4 alloy， while the solution heat treatment temperatures above the γ' phase dissolution temperature weakens the pinning effect of coarse γ' phase on RX growth， and high melting point carbides and residual eutectic become important factors hindering RX growth. In addition， the high content of Co element reduces the stacking fault energy of the CMSX-4 alloy， making it with a high recrystallization tendency.
The effects of solid solution temperature and aging time on the microstructure and mechanical properties of Inconel 617 superalloy are studied by using optical microscope， scanning electron microscope， and transmission electron microscope. The results show that the main precipitated phase in the solid solution microstructure of Inconel 617 superalloy is M 23C6 type carbide， and the nucleation growth is preferentially at the grain boundary. With the increase of solid solution temperature， the grain boundaries and intragranular carbides undergo two processes： first growing and then dissolving， and the average growth rate of the grain size also increases. As the aging time prolongs， the γ′ phase precipitates dispersedly and distributes uniformly in the microstructure，showing a trend of grain quantity decrease and grain size increase. As the size of the γ′ phase increases， its lattice mismatch also increases， and the elastic strain field around the γ′ phase is enhanced， resulting in a more obvious strengthening effect. High- temperature tensile properties testing shows that the tensile strength and yield strength of Inconel 617 alloy gradually decrease at 750 ℃ with the increase of solid solution temperature， while they gradually increase at 900 ℃. The grain boundary strength of Inconel 617 alloy is higher than the inner grain strength at ≤750 ℃， while the inner grain strength is higher than the grain boundary strength at 900 ℃. The tensile strength and yield strength of Inconel 617 alloy at 750 ℃ increase gradually with the aging time.
The filling and solidification processes in investment casting of typical K4169 nickel-based superalloy complex thin-walled casting are simulated by ProCAST finite element software.The temperature field during the casting process is analysed to predict the formation of defects. The complex thin-walled casting is produced by investment casting with the same process parameters， and its shrinkage level， microstructure， and tensile mechanical properties are studied.The results show that when the pouring temperature is 1530 ℃ and the preheating temperature of the mold shell is 1000 ℃， the filling of the molten metal is stable. The solidification conforms to the principle of sequential solidification. The overall defects of the casting are less； the micro-shrinkage average volume fraction of different parts is counted， and the highest is only 1.01%； the minimum secondary dendrite arm spacing（SDAS） in the thin-walled region is only 18.4 μm， and the maximum secondary dendrite spacing in the thick part is 38.8 μm； the as-cast microstructure of K4169 alloy is dendritic structure. After standard heat treatment， the dendrites grow and coarsen， and the dendritic morphology in the grains is not obvious. The average room temperature tensile strength of the standard heat-treated K4169 alloy is 785.0 MPa， the average yield strength is 659.7 MPa， and the average elongation is 13.9%. The difference in shrinkage porosity level significantly affects the tensile strength and yield strength， but the elongation change is not obvious.
A large number of droplets and their products produced by titanium fire combustion in aeroengine compressor will cause burn through and non-inclusiveness failure of titanium alloy casing. This has shown great harm. In this study， a quantitative evaluation method for titanium fire inclusiveness of compressor was explored based on the mechanism of titanium alloy melt drop ablation and laser ignition technology. A test and evaluation method was established with the characteristic parameters of the melt drop penetration resistance of two configurations of TC4 titanium alloy casing， namely horizontal expansion and vertical drip. Meanwhile， the diffusion behavior of titanium fire and the critical failure conditions under simulated airflow environment were varified by experiments as well. Those results show that the mechanism of titanium alloy droplet burning through the casing lies in the local high heat concentration formed at the droplet contact interface. Under the action of heat transfer， the kinetic energy of the atoms in the base of the titanium alloy cartridge increases rapidly， forming a penetrating liquid phase， and finally causing burn-through， that is， titanium non-inclusiveness failure. When the droplet moves horizontally in the process of extended combustion， it will be affected by some mechanism such as reverse airflow， which will weaken the expansion effect. When the droplet is adhered to the surface of the casing simulation for a long time under the action of gravity or centrifugal force， the heat released is enough to burn through the titanium alloy casing. Its critical thickness is between 1.5-2 mm.
Due to the large temperature gradient in the laser melting deposition process， the coarse primary β columnar grains with preferred orientation are formed along the deposition direction， resulting in significant anisotropy of materials. This study aims to change the morphology of the primary β grains， refine the microstructure and weaken the texture of titanium alloy by adding Cu element in the materials during the process of laser melting deposition. The effects of Cu content on the microstructure and texture of TC4 titanium alloy manufactured by laser melting deposition are studied systematically. The results show that Cu element addition can refine the columnar primary β grains significantly and make the grain size distribution more uniform. The columnar grains are transformed to fully equiaxed grains when 4% Cu （mass fraction， the same as below） is added into the material， and the average size of primary β grains decreases to 385 μm from 1490 μm of TC4 titanium alloy. Basket-weave microstructure composed of α-Ti， β-Ti， and a small amount of Ti2Cu is obtained inside primary β grains of the samples with Cu addition. The short rod-like Ti2Cu distributes at the boundary of the α-Ti lath， and its proportion in the microstructure increases with the increase of Cu addition. The average width of α-Ti is 0.44 μm when 8% Cu is added， which is reduced by about 63% compared with 1.18 μm of the sample without Cu addition. When 4% Cu is added， the maximum multiples of uniform distribution（MUD） value of α-Ti pole figure is reduced by about 71% compared with TC4 titanium alloy，which demonstrates that the addition of Cu can significantly reduce the texture strength of titanium alloy manufactured by laser melting deposition.
The cooling rate after high-temperature heat treatment has a significant effect on the microstructure and properties of Ti65 alloy. The effect of cooling medium temperature on the cooling curve and microstructure of Ti65 alloy after high-temperature heat treatment has been systematically studied. The results show that the temperature of the oil medium has an opposite effect on the cooling curve to that of the air medium. The maximum cooling rate of oil is 73.2 ℃/s at room temperature， while the maximum cooling rate of air cooling is only 11.2 ℃/s. As the temperature increases， the cooling rate curve for oil quenching condition shifts to the right， and the maximum cooling rate and the minimum film boiling temperature increase. When the oil temperature is in the range of room temperature to 60 ℃， the cooling rate curve for oil quenching condition includes vapor， boiling， and convection three stages. When the oil temperature rises to 80 ℃， the vapor stage disappears. In addition， the microstructure shows a transition trend from α+β dual-phase microstructure to martensitic microstructure with the increase in oil temperature. Conversely， with the temperature increases， the cooling rate curve for air cooling condition shifts to the left， the maximum cooling rate decreases， and the temperature at the maximum cooling rate in the boiling stage gradually increases. Compared with oil quenching at different temperatures， the microstructure of air cooling under different temperatures shows typical bimodal microstructure with no obvious difference. The effect of oil temperature on the cooling curve is mainly attributed to changes in oil viscosity and fluidity， while the effect of air temperature on the cooling curve is mainly attributed to multiple complex factors such as air density and temperature gradient.
The hot isostatic pressing process is a usual powder Ti2AlNb alloy preparation method to deeply study the influence of factors such as the powder-making process on the properties of Ti2AlNb powder alloy.Ti2AlNb pre-alloyed powders are prepared by plasma rotating electrode process and electrode induction melting gas atomization， respectively， and their mixed powders are characterized. Ti2AlNb alloy is prepared using a hot isostatic pressing process.The effects of the powder-preparing process， porosity， and inclusion on the microstructure and mechanical properties of the Ti2AlNb alloy are investigated. Optimized processes are employed for the forming of various Ti2AlNb powder metallurgy components. Experimental results show that the powder-making processes affect the durability of the powder alloy， the pore defects caused by slight capsule gas leakage significantly reduce the mechanical properties of the powder Ti2AlNb alloy， and the inclusions obviously affect the consistency and stability of the room-temperature tensile properties of the powder alloy.
To meet the application requirement of advanced aviation engines for complex shell castings of high-strength and heat-resistant aluminum alloys， the process and mechanical properties of a new type of the Al-Si-Cu-Mg-Sc high-strength and heat-resistant aluminum alloy are analysed in comparison with ZL101A and ZL205A cast aluminum alloys. Design and experimental verification of the metal casting process for the complex casing of the oil pump are carried out by using the high-strength and heat-resistant aluminum alloy， and the quality of the casting products is evaluated. The results indicate that the new high-strength and heat-resistant Al-Si-Cu-Mg-Sc alloy shows better casting fluidity and hot cracking resistance than the ZL205A high-strength cast Al alloy. The qualification rate of the complex shell of its metal casting oil pump is comparable to that of the same type of shell ZL101A. The average tensile strengths at room temperature of the separated test bar of casting and test specimen from casting itself of the new alloy are higher than 420 MPa， which are significantly higher than that of ZL101A alloy， while the tensile strengths at 250 ℃ are superior to ZL205A alloy. The surface quality， internal quality， airtightness， and pressure resistant performance of the casting case all meet the design requirement of the product.
Continuous alumina fiber reinforced alumina composite （Al2O3f/Al2O3） is an ideal material for developing high-performance aero-engine hot section components. In this study， the room-temperature and 1000 ℃ tensile mechanical properties of domestic Al2O3f/Al2O3 are investigated. The microscopic morphology and fracture morphology of tensile specimens are observed by SEM. The microstructure is observed by TEM. The tensile strength is analyzed using the Weibull distribution， and the fiber/matrix interfacial shear strength is obtained by the fiber push-in method. The results show that the room-temperature tensile strength of domestic Al2O3f/Al2O3 is （257±31） MPa while the tensile strength at 1000 ℃ is 78% of room temperature strength， reaching the level of foreign Nextel610/Al2O3. The interfacial bonding is the main factor affecting the tensile strength. High tensile strength with low interfacial bonding strength， results in long and dispersed fiber pull-out. Low tensile strength with high interfacial bonding strength， results in fiber bundle breakage and shorter fiber pull-out.
To investigate the effect of the spraying process parameters on the properties of NiCoCrAlYTa-Cr2O3-Cu-Mo high-temperature wear-resistant coating， the coating is prepared by atmospheric plasma spray （APS） process based on the orthogonal experiment. The range analysis method is used to study the primary and secondary relationships of the process parameters on the microstructure， hardness， and bonding strength of the NiCoCrAlYTa-Cr2O3-Cu-Mo coating， and the spraying process parameters are optimized. The optimized process parameters are that the argon flow rate is 50 L/min， the hydrogen flow rate is 12 L/min， the current is 500 A， and the spraying distance is 100 mm. With the optimized spraying process parameters， the microstructure of the coating is very dense， the porosity is lower than 1%， and the average bonding strength， hardness， and average oxidation speed during 50-100 h at 900 ℃ are 70.7 MPa， 543.7 HV， and 0.07302 g/（m2·h）， respectively. In addition， the friction coefficient and wear rate of NiCoCrAlYTa-Cr2O3-Cu-Mo coating are 0.248 and 2.12×10-6 mm3/（N·m） at 800 ℃， exhibiting good friction and wear properties.
The two-dimensional triaxially braided composites are prepared by the resin transfer molding process. The mechanical response of two-dimensional triaxially braided composite under high and low velocity impact are investigated through the air gun system and drop hammer impact test system with different energies. The delamination damage under different impact energies are obtained by ultrasonic C-scan to analyze the damaged failure characteristics. The behaviors of compression after impact are studied in combination with digital image correlation. It is shown that the damaged area of the two-dimensional triaxially braided composite increases proportionally with the low velocity impact energy， but the energy absorption increases almost 2 times. Severe damage occurs and extends along the axial fiber under impact with an energy of 6.7 J/mm， leading to a significant reduction in its residual strength. The ballistic limit velocity of the two-dimensional triaxial braided composite is about 138.5 m/s. The projectile is embedded in the plate. When the impact velocity is greater than the ballistic limit velocity， a rectangular hole is formed on the impact surface， and a tearing fracture can be observed on the back surface. The damage area decreases with the increase of the incident velocity.
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