- 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)
Cold spraying technology has a number of unique characteristics， most notably the solid-state metal powder deposition. This property confers the technology with significant technical advantages and application potentials in the domains of coating preparation， high-efficiency and high-speed repair， and additive manufacturing. Nevertheless， when applying for high-strength nickel-based superalloy materials， this technology remains confronted with significant technical challenges， including high coating porosity， inadequate strength， and an absence of plasticity. In this paper， the critical deposition conditions and influencing factors of cold-sprayed superalloys are systematically reviewed， focusing on the microstructure characteristics of deposited materials and their correlations with properties （especially tensile properties）， and summarizing the main methods of microstructure and performance optimization， such as post-spray heat treatment， post-spray hot isostatic pressing， laser-assisted cold spraying， and in-situ shot peening-assisted cold spray deposition. In the future， for expanding the engineering applications of cold-sprayed high-temperature alloys， it is necessary to modify the particle deformation conditions and expand the deposition window， to develop the hybrid treatment methods to improve the coating property， as well as lowering the process costs. These measures will provide a theoretical basis and technical guidance for its applications in the fields of aerospace.
The improved process combining a polybenzimidazole （PBI） polymer nozzle with axial center powder feeding is employed to study the nozzle clogging behavior and its impact on coating deposition. Multi-scale characterization of the coating morphology and microstructure is carried out using X-ray computed tomography（X-CT）， optical microscopy， and electron backscatter diffraction. The results show that in the existing process， aluminum powder softening causes adhesion to the inner wall of the SiC nozzle， forming clogging materials. This leads to a powder agglomeration on the coating surface and a porosity of 0.32%. In contrast， the PBI nozzle， when used with the axial center feeding process， significantly reduces particle adhesion and forms a uniform gas-solid two-phase flow， enabling continuous and stable deposition. The resulting coating exhibits significant internal particle plastic deformation with the porosity reduced to 0.16%. Based on the optimized process， aluminum metal additive manufacturing experiments are carried out， achieving continuous spraying for 2 h without nozzle clogging and depositing a 38 mm thick coating on an aluminum alloy substrate. X-CT analysis indicates that there are no significant defects at the interface or within the deposit. The in-plane and out-of-plane tensile strengths of the deposit are about 180 MPa and 80 MPa， respectively， indicating significant anisotropy.
To solve the problem of cavitation protection on the surface of aluminum alloy flow-handling components， Ti6Al4V coatings are prepared by in-situ micro-forging assisted cold spraying. Large-size 202 stainless steel particles are mixed into Ti6Al4V powder during the spraying process to promote the plastic deformation of Ti6Al4V powder and form dense coatings. The effects of cold spraying process parameters on the quality of Ti6Al4V coating are investigated using optical microscopy，scanning electron microscopy， microhardness tester， ultrasonic cavitation testing machine， and 3D profilometers， leading to the determination of the optimal process parameters. The results show that the porosity of Ti6Al4V coating decreases with the increase of shot peening particle content. When the shot peening content is 70%（volume fraction）， the Ti6Al4V coating is compact and the porosity is only 0.46%. The microhardness of the coating gradually increases to 394HV0.3， which is higher than the microhardness of forged Ti6Al4V alloy（370HV0.3）. The cavitation erosion test results show that the cavitation erosion depth of Ti6Al4V coating is only 4.742 µm after 2 h cavitation erosion， and the cavitation erosion resistance of Ti6Al4V coating is 77 times that of Al substrate （365.199 µm）. The Ti6Al4V coating prepared by in-situ micro-forging cold spray is dense， has high hardness， and exhibits good interparticle bonding， effectively inhibiting the initiation and propagation of cracks during cavitation， which leads to particle detachment. Therefore， it possesses excellent cavitation erosion resistance.
In the connection between aero-engine blades and disk tenon grooves， CuNiIn alloy is frequently applied as an anti-fretting wear coating. To investigate the effects of heat treatment processes on the microstructure and properties of the coating， this study employs the cold spraying technology to prepare CuNiIn coatings on TC4 alloy. The influences of two process parameters（heat treatment temperature and holding time） on the coating’s microstructure， microhardness， bonding strength， and fretting wear perfor-mance are analyzed and compared. The results indicate that after heat treatment， the pores in the coating undergo healing， and the porosity of the coatings decreases from 7.4% in the as-sprayed state to 0.8%（700 ℃），resulting in a more uniform distribution of microhardness. Considering overall performance， the coating exhibits optimal properties after being held at 500 ℃ for 3 h. At this stage， the porosity is 1.1%， the bonding strength reaches 54 MPa， and the coating microhardness remains at 131HV. The wear rate significantly reduces， with the dominant wear mechanism shifting from abrasive wear to adhesive wear.
Cold-sprayed Zn-Al composite coatings can provide good corrosion resistance for magnesium alloys. This experiment employs AZ31B magnesium alloy as the substrate for the deposition of a Zn-Al composite coating.To further improve the performance of cold-sprayed Zn-Al composite coatings， the coatings are subjected to annealing treatment at 200， 250 ℃， and 300 ℃. The microstructure morphology and properties of the cold-sprayed Zn-Al composite coatings before and after heat treatment are analyzed by X-ray diffractometer （XRD），scanning electron microscope （SEM）， microhardness tester， electrochemical workstation，and salt spray corrosion test equipment. The results show that after annealing treatment at different temperatures， the coatings do not undergo oxidation or phase transformation， and the microstructure of the coatings becomes denser and the corrosion resistance improves after annealing treatment. With the increase of annealing temperature， the coatings show the phenomenon of annealing hardening. When the annealing temperature is 250 ℃， the composite coatings are the densest， and the porosity is 0.3998%. Electrochemical and salt spray tests show that the coatings after annealing treatment form a dense corrosion layer， which improves the corrosion resistance of the coatings. When the annealing temperature is 250 ℃， the corrosion resistance of the coatings is the best.
Cobalt-based superalloys are widely used in aerospace，energy power，and nuclear industries due to their excellent resistance to thermal corrosion and fatigue，as well as good weldability. However，high-temperature oxidation leads to performance degradation of the alloys， becoming a key factor limiting their service life. This paper reviews the progress in the study of oxidation behavior of cobalt-based superalloys，focusing on the different stages of oxidation and their mechanisms of the oxidation process. It further explores the effects of alloying elements and temperature on the formation and evolution of oxide scales，and critically analyzes the limitations and challenges of current research. Finally，it points out that future key research directions include the design of novel cobalt-based superalloy compositions and the optimization of synergistic mechanisms， control of oxide scale and phase transformations， as well as conducting oxidation studies under dynamic environments combined with intelligent methods to accelerate materials optimization.
Carbon fiber reinforced polymer （CFRP） has the characteristics of high specific strength/modulus and strong designability， which has been widely used in aerospace and transportation. CFRP is mainly composed of carbon fiber， resin matrix and the interface between them. As a component of CFRP， the interface poses great influence on the properties of the composite. Due to the smooth surface morphology and chemical inertness as well as significant difference in the elastic modulus between the matrix， the interfacial compatibility of CFRP is rather poor. Therefore， searching for suitable interfacial modification methods has become a hot research topic. In this paper， interface modification methods of CFRP， including the conventional approaches and state-of-the-art approach based on multi-scale interface microstructure construction， as summarized. In general， the multi-scale interface microstructure construction method is advantageous over the conventional methods in regard to interface modification effect， which can change the physical and chemical properties of the fiber surface and alleviate the stress concentration caused by the large modulus difference between the fiber and the resin. Outlook is given on the trend of composite interfacial modification method based on multi-scale interfacial phase construction：exploring accurate interface normal characterization methods combined with micro and nano technologies， while developing controllable interface microstructure construction processes， and exploring a set of efficient and low-cost multi-scale interface construction methods， ultimately achieving the practical engineering application of the multi-scale interface microstructure construction method.
The interfacial properties of carbon fiber reinforced polymer （CFRP） composites have an important influence on the physicochemical properties of CFRP， which is a research hotspot in the field of composites technology. Mussel-inspired surface modification method based on dopamine chemistry is an emerging class of surface interface modulation means in recent years， and it has also been applied in the field of CFRP interfacial enhancement research， which has a lot of advantages such as simplicity， high efficiency， environmentally friendly， low cost， etc. Especially， the dopamine-assisted co-deposition modification method has great potential for application. This paper focuses on the research progress of dopamine in CFRP modification， which includes a discussion of the classification of dopamine-modified carbon fiber treatments. Finally， it is pointed out that the polymerization deposition mechanism of dopamine-modified carbon fibers still needs systematic in-depth study， and the control factors of polymerization deposition rate and coating morphology and structure need to be further clarified as the focus of future research.
Fiber absorbent has been applied in the field of stealth and electromagnetic compatibility due to its advantages of broadband absorption，light weight，and corrosion resistance. Analyzing the research progress in this field is of great significance for the design of broadband and efficient absorbing materials. This paper discusses the action mechanism，numerical simulation method，factors affecting electrical properties，and preparation technology of fiber absorbents. Both the dielectric loss mechanism based on dielectric constant and the ohmic loss mechanism based on impedance are used to explain the microwave absorption mechanism of this kind of material，which is verified by theory and experiment. Through the full-wave theoretical simulation，the electrical properties of complex structure and high concentration fiber absorbers can be better analyzed. The parameters such as fiber type，content，and length have a great impact on their electrical properties，which are widely used in the preparation process. It is particularly important to select appropriate ultrasonic dispersion parameters and dispersants. In the future，further research can focus on the distribution of current and electric field distribution in fiber absorbers to clarify the interaction and coupling mechanisms between fibers. Under the same conditions （such as fiber content and length），the effects of fiber type and electrical conductivity on electrical performance should be compared，along with the differences between carbon fibers of different specifications. These efforts aim to achieve optimal performance in terms of broadband response，high efficiency，and thickness. This review holds great significance for the design of broadband and high-efficiency microwave-absorbing materials.
Additive friction stir deposition （AFSD） is a technology with several advantages for aerospace manufacturing. It is particularly valuable because it can deposit materials at low temperatures while retaining high quality and efficiency. This article introduces the operations of AFSD in detail and investigates its effect on three types of precipitation-reinforced aluminum alloys. Key challenges hindering the production of high-strength aluminum alloy components through AFSD are highlighted. AFSD utilizes solid-phase deposition to avoid problems like porosity and thermal cracking that can occur with other types of deposition， such as laser and arc depositions. However， the slow cooling of the deposited metal and the long residence time in the sensitive temperature range can cause issues. Subsequent layers exert a thermal effect on the previous layers during the AFSD process. This can lead to coarsening of the precipitates in the middle and lower regions， resulting in decreased strength in these areas. The top layer remains unaffected， but has poorer mechanical properties compared to the base material. To improve performance， aging treatment can be used to cause reprecipitation of some elements dissolved during AFSD， but it does not reach the values achieved by solid solution and aging （T6） treatment. T6 treatment after AFSD can renew uniformly distributed fine-strengthening precipitates， but it triggers abnormal grain growth （AGG） in the deposited material. Therefore， it is generally not recommended to subject solution treatment to metals deposited with AFSD. Further research should focus on alloy design， composite reinforcement and innovative techniques， which are essential to obtain high-strength precipitation-reinforced aluminum alloy components through AFSD.
The interfacial structure of carbon fiber-reinforced polymer （CFRP） is crucial to the performance of composites， which represents a fundamental aspect of composite materials science research. The research on carbon fiber surface treatment is an important part of the research on composite material interfaces. By changing the physicochemical structure of the carbon fiber surface， better interface properties can be imparted to the composites. In this paper， an anodic oxidation surface treatment method based on acidic medium is adopted. Dilute sulfuric acid solutions of different concentrations are used as electrolytes to construct functional groups on the carbon fiber surface at different current densities. The results show that the carbonyl functional group （C O） plays an important role in the interface properties of CFRP. In anodic oxidation treatment， a lower current density is conducive to generating more C O on the surface of carbon fiber. There is an optimal value for the influence of sulfuric acid concentration on C O. Moreover， adjusting the sulfuric acid concentration can achieve more accurate construction of C O on the carbon fiber surface. When the current density is 0.31 mA/cm2 and the sulfuric acid concentration is 0.3%（mass fraction）， the C O content on the carbon fiber surface reaches the maximum value of 6.49%， and the interfacial shear strength with epoxy resin also reaches the maximum value of 76.9 MPa. Compared with untreated carbon fibers， it is increased by 111.3%， reflecting a strong correlation. This is because the dispersion interaction between C O and the groups in epoxy resin enhances the bonding ability between carbon fiber and epoxy resin.
Based on finite element method and cohesion method， a three-dimensional model of SiC/AZ91D composite materials with varying void contents is constructed. The impact of void content on the mechanical behavior of the composite materials is investigated employing the stress concentration factor method， and an in-depth exploration of the failure mechanism is conducted.The findings reveal that the increase in void content will lead to a decrease in the mechanical properties of composite materials. The crack appearance and extension time of cracks are accelerated with an increasing void content. During the elastic deformation phase， the primary load is borne by the matrix， and the fluctuation in void content has a comparatively negligible effect on the stress concentration factor. Upon entering the plastic deformation phase， the load is progressively transferred from the matrix to the SiC particles. With an elevated void content， the load transferred from the matrix to the SiC particles diminishes， causing a deceleration in the growth rate of the stress concentration factor.
In this study，alumina powder is used as the matrix material，and two organic alumina precursors with different room-temperature phases （solid-phase and liquid-phase） are selected as sintering aids，and the solid-state sintering process is adopted. To explore the regulatory effect of the precursors on the sintering temperature of alumina ceramics，controlled experiments are designed with sintering temperature，precursor type，and additive content as key variables. Through physical and chemical property characterization and mechanical performance testing of samples in each group，the sample performance under different process conditions is systematically evaluated. The results show that both solid-phase and liquid-phase organic alumina precursors can significantly reduce the sintering temperature of alumina ceramics，and the optimal additive amounts of the two precursors vary at different sintering temperatures. Within the temperature range of 1200-1400 ℃，the optimal additive amount of both precursors is the same，which is 6%. When the sintering temperature increases to 1500 ℃，the optimal additive amount of the solid-phase precursor decreases to 2%，while that of the liquid-phase precursor increases to 10%. This work provides experimental basis for the optimization of low-temperature sintering process and parameter selection of alumina ceramics，and has reference value for promoting their efficient preparation.
Amoxicillin （AMX） exhibits good chemical stability but low biodegradability. To address the water pollution problem caused by AMX，hollow-structured Fe3O4@mesoporous TiO2（FT） photoelectrocatalytic materials are prepared，and the visible-light photoelectrocatalytic degradation of AMX wastewater is investigated. Characterizations show that FT consists of spherical particles with an average particle size of 400 nm，possessing a typical mesoporous structure，anatase TiO₂ crystal phase，and good magnetic responsiveness （saturation magnetization of 24.90 emu·g-1）. It can be efficiently separated by an external magnetic field and uniformly redispersed after ultrasonic treatment. Electrochemical test results indicate that the electroactive surface area of ITO+FT reaches 2.39±0.01 cm²，which is significantly larger than that of ITO and ITO+FST. Meanwhile，ITO+FT has lower charge transfer resistance and higher photogenerated electron-hole separation efficiency. Visible-light photoelectrocatalytic degradation experiments of AMX show that the degradation rate of the FT photoelectrode reaches 88.1% within 60 min and increases to 98.3% at 100 min. After 8 cycles，the degradation rate remains above 89%，demonstrating excellent stability. Active species trapping experiments confirm that ·OH and h⁺ are the key active species in the reaction. Combined with the confined catalytic effect of the hollow structure of FT，the photoelectrocatalytic degradation mechanism is proposed. This study demonstrates good feasibility in destroying the molecular structure of AMX，so it can serve as an effective pretreatment method for AMX wastewater and provides a new type of recyclable photoelectrocatalytic material and technical scheme for the efficient pretreatment of AMX wastewater.
Using the conventional solid-state method， high-entropy ceramics with a perovskite structure （Ca0.25Sr0.25Ba0.25Pb0.25）（Zr x Ti1- x ）O3 are prepared. The effects of configurational entropy and annealing heat treatment on the phase composition， microstructure， and thermal conductivity of the ceramics are investigated. The results show that the combined influence of entropy engineering and heat treatment processes results in an increase in the porosity of the ceramics， the precipitation of the PbO nano-second phases with low thermal conductivity， a reduction in the average grain size， and a significant reduction in the thermal conductivity. The structural disorder introduced by the high-entropy composition effectively enhances the stability of the thermal conductivity and imparts glass-like thermal transport characteristics to the ceramics. When x=0.20， the ceramic exhibits optimal thermal insulation performance and thermal conductivity stability， with κ 800 ℃=0.89 W·m-1·K-1 and Δκ 100-800 ℃=0.07 W·m-1·K-1， providing alternative materials for high-temperature thermal insulation applications.
Hot extrusion is the main process for the production of zirconium alloy tubes， rods and profiles. However， zirconium alloy is easy to adhere to the mold under hot extrusion， and is difficult to lubricate， which greatly affects the machining accuracy and mold life. To solve the lubrication problem of zirconium alloy hot extrusion，low melting point borate glass and two-dimensional layered lubricants （MoS2， graphite， etc.） are added into the PVA modified silicate coating to obtain good wetting property and high temperature wear resistance. In this study， the high-temperature physical and chemical properties of materials are studied through thermogravimetric analysis and differential scanning calorimetry. X-ray photoelectron spectroscopy and Fourier infrared spectroscopy are used to analyze the functional groups and chemical bonds of PVA-modified binders. For lubricating coatings， cross-cut test is taken to test the adhesion of the coating. X-ray diffractometer is used to test the phase change at high temperature. The lubrication performance is characterized by a high-temperature friction testing machine. After friction， optical microscopy and scanning electron microscopy are used to study the surface interface microstructure of the wear track. Energy dispersive X-ray spectroscopy is used to analyze the distribution of elements and phase composition in the wear track. After PVA modification， the contact angle between the lubricant slurry and the surface of the zirconium alloy is reduced from 64° to 43°， which is conducive to the spreading of the lubricant on the surface of the zirconium alloy. Moreover， the microhardness of the lubricating coating increases from 92HV0.1 to 149HV0.1， and the dropout rate is reduced from 42.5% to 9.1%. It is indicated that the mechanical properties of the coating are significantly improved. The high temperature oxidation experiment of 700 ℃ is carried out on the lubricating coating. The results show that the PVA-modified silicate lubrication coating still contains a certain amount of MoS2. In contrast， there is almost no molybdenum disulfide in the lubricating coating that has not been modified with PVA， and even the zirconium alloy substrate is oxidized. This can be attributed to the C—O—Si bonds formed by PVA and silicates forming an inorganic silicon network structure in the coating， which plays a role in isolating air and preventing oxidation. In the friction experiment， the prepared coating can be effectively lubricated at 700 ℃. This is due to the fact that the molten glass powder itself has a certain lubricating ability at high temperature， coupled with the unoxidized two-dimensional layered lubrication materials， MoS2 and graphite， so as to achieve excellent high-temperature lubrication performance. In this study， the prepared coating demonstrates good high-temperature lubrication performance， thermal protection performance， and ease of removal. It shows promising potential for application in the hot extrusion lubrication of difficult-to-process metals such as zirconium， titanium， and hafnium.
CuS nanoparticles are introduced into a thermoreversible polyurethane based on Diels-Alder （DA） bonds and disulfide bonds，successfully yielding a self-healing polyurethane with five-fold response to thermal，near-infrared light，microwaves，solar light，and UV. When the CuS content is 0.3% （mass fraction），the modified polyurethane achieves optimal comprehensive mechanical properties and self-healing performance. After damage such as cracks or fractures in the modified polyurethane occurs，the material can be restored repeatedly through heat-treated at 120 ℃ for 6 min，irradiated with 4 W/m2 of near infrared light at a wavelength of 808 nm for 60 s，or treated under a 250 W microwave for 80 s，and followed by a heat treatment for 12 h at 60 ℃. In addition，the damaged sample can also be repaired multiply after being treated to a simulated solar light or irradiated through UV for 6 h. The results show that the near-infrared light response offers the quickest self-healing speed，shortest repair time and highest repair efficiency. The self-healing behavior is achieved through the cooperation of thermoreversible DA reaction，disulfide bonds exchange，dissociation and regeneration of hydrogen bonds，directional migration of CuS nanoparticles，and thermal movement of molecular chains. These findings have important guidance for the development of multi-responsive self-healing materials with efficient self-healing capability and provide various ideal selections for damage repair under different environments.
To reduce the Curie temperature of iron-nickel soft magnetic alloy materials and improve their temperature applicability in the field of smoke heating， powder metallurgy is used to prepare iron-nickel alloy soft magnetic materials. The alloy powder of different components is pressed by ball grinding mixture and vacuum sintering at 1380 ℃ and 1400 ℃. The influence of Cr addition on the tissue properties of FeNi alloy is analyzed by X-ray diffractometer （XRD），electron probe microanalyzer，soft magnetic DC B-H meter， and PPMS. The results show that the samples produced at a sintering temperature of 1400 ℃ have a uniform and dense organization with better comprehensive magnetic and electrical conductivity. The magnetic performance of soft magnetic materials is closely related to the composition. The addition of Cr improves the density and hardness of FeNi alloys，together increases the resistivity of FeNi alloys，while decreases the magnetic permeability and the Curie temperature significantly.
The Al-C-X（X=Mo，Nb，Ta，V） systems are studied by CALPHAD （calculation of phase diagrams） coupled with first-principles calculations. Two ternary phases，Ta5Al3C and Ta2AlC are identified in the Al-C-Ta system. All of the other three systems exist only one stable ternary phase， Mo3Al2C for Al-C-Mo， Nb2AlC for Al-C-Nb， and V2AlC for Al-C-V， respectively. The enthalpies of formation of these compounds are obtained by First-principles calculations， and their Gibbs free energies are presented by stoichiometric models. Finally， a series of self-consistent thermodynamic parameters are derived by CALPHAD method. The optimized isothermal sections and thermodynamic properties are in good agreement with experimental and computational results. The Al-C-X （X=Mo，Nb，Ta，V） systems assessed in this work can help to establish a thermodynamic database of hard alloys with precipitation strengthening bonding phases， which will be used to guide the design of new materials with excellent properties.
To characterize the grain morphology from multiple apsects such as size， shape and distribution， and then realize the quantitative ultrasonic evaluation of the uniformity of grain morphology， an ultrasonic multi-parameter evaluation method for grain morphology is proposed. GH738 grain morphology is used as the characterization object， and 10 quantitative parameters are extracted with the grain as the measurement unit. Eight quantitative parameters are measured for the field-of-view image. The correlation screening rule using pearson coefficient is established， then seven metallographic quantitative parameters are selected， the radial layout visualization star coordinate method is used to calculate two parameters， r and ， which are used to comprehensively characterize grain morphology. Six ultrasonic parameters， such as sound velocity and attenuation coefficient， are extracted， and a sample library of two-dimensional comprehensive characterization parameters of grain morphology and ultrasonic multi-characteristic parameters is established. Three ultrasonic evaluation model based on MLR， RFR or PSO-SVM algorithm are built to characterize the two comprehensive parameters of grain. The verification experimental results show that the multi-dimensional comprehensive characterization of grain morphology is feasible.The ultrasonic evaluation model based on MLR has a higher accuracy and more balanced evaluation for two parameters.
According to the maximum solid solubility of Zn， Mg， Cu in aluminum and their precipitation strengthening phases， Al-12Zn-2Mg-0.5Cu-0.3Sc high strength aluminum alloy is designed. The billet of this alloy is hot rolled followed by clod rolling and heat treatment to explore the optimal heat treatment process for aluminum alloy with high solid solubility to obtain good tensile properties. Optical microscopy （OM）， X-ray diffractometry （XRD） ， and scanning electron microscopy （SEM） are used to observe and analyze the microstructure of the alloy under different heat treatment conditions， and universal tensile testing machine is used to test the tensile properties of the alloy at room temperature. The results show that after solution treatment of 470 ℃/1 h， the microstructure of the cold-rolled alloy is incomplete recrystallized with elongated grains along the rolling direction. The ultimate tensile strength of the alloy is 599 MPa， and the elongation reaches 15.4%. After aging treatment of 120 ℃/30 h， fine η （MgZn2） and T（AlZnMgCu） strengthened phases precipitate in the microstructure， which further improve the properties of the alloy. The corresponding tensile strength reaches 736 MPa， and the elongation is 10.6%.
To promote the further application of high-strength aluminum alloys in the aviation field，the 7050-T7451 aluminum alloy with 4 mm thickness is carried out by laser-melt inert-gas（MIG）hybrid welding. The results show that a well-formed weld seam can be obtained with reasonable matching of welding parameters，while welding at higher speeds is easy to produce cracks. When the welding speed is controlled at 0.9 m/min or below，and the weld back-width ratio is controlled above 0.4，the cracks and porosity defects can be effectively suppressed. The weld zone is mainly composed of equiaxed grain structures with significant differences in size. Near the fusion zone，there is a fine-grained layer approximately 20-50 μm wide，and only a minimal amount of columnar grains forms adjacent to this fine-grained layer. No phase transformation or recrystallization occurs in the heat-affected zone. The as-welded joint achieves an average tensile strength of approximately 377 MPa， equivalent to about 73% of the base metal strength， significantly outperforming the tensile properties of laser self-fusion welded joints.
To study the corrosion behavior and differences between 1070A and 6063 aluminum alloys in simulated marine atmospheric environments， the corrosion processes of 1070A and 6063 aluminum alloys in marine atmospheric environments are simulated by indoor cyclic salt spray experiments. The corrosion morphology， pitting parameters and the corrosion products of the 1070A and 6063 aluminum alloys are observed and detected by ultra-depth-of-field microscope and X-ray diffractometer respectively. The corrosion mass loss of 1070A and 6063 aluminum alloys is analyzed by corrosion kinetics methods. The differences of corrosion behaviors between the 1070A and 6063 aluminum alloys are analyzed by electrochemical impedance and polarization curves. The test results show that pitting corrosion is the main corrosion form on 1070A and 6063 aluminum alloys in the simulated marine atmospheric environment. With the extension of corrosion time， the average pitting depth， the maximum pitting depth and the pitting density gradually increase. The corrosion behaviors of 1070A and 6063 aluminum alloys are similar in the early stage of corrosion test. However， the pitting depth and pitting density of 6063 aluminum alloy doubled in the later corrosion stage， which is due to the re-cracking of the surface corrosion layer， resulting in a serious increase in the corrosion degree of 6063 aluminum alloy. What’s more， the corrosion mass loss and corrosion time of both 1070A and 6063 aluminum alloys show a power exponential relationship. Combined with the analysis of electrochemical impedance spectra and polarization curves， it is confirmed that the 6063 aluminum alloy is more susceptible to corrosion in simulated marine atmospheric environments， with a higher degree of corrosion compared to 1070A aluminum.
To investigate the impact of substrate roughness， crystal type， and coefficient of thermal expansion （CTE） on the stress of electroplated copper films， an experiment is conducted utilizing four distinct substrate types： smooth sapphire， rough sapphire， amorphous sintered alumina， and pure copper. The copper films are electroplated onto the substrate surfaces and subsequently annealed. Pre- and post-annealing measurements are taken to assess warp and a stress. Electron backscatter diffraction （EBSD） is employed to study the microstructural transformation of the copper films. The experimental results reveal that annealing transforms the copper film stress from compressive to tensile， with stress levels decreasing in the order of sintered alumina， smooth sapphire， rough sapphire， and pure copper substrates. Additionally， annealing leads to significant grain growth. Analysis indicates that post-annealing copper film stress arises from CTE mismatch and volume shrinkage. Stress reduction in copper films can be achieved by selecting rough single-crystal substrates and materials with CTEs close to that of copper. These experimental findings contribute valuable insights to the study of electroplating stress and the selection of appropriate electroplating.
To study the impact of V-notch radius on the mechanical properties of TA15 titanium alloy，tensile，stress-rupture，fatigue tests and fracture analysis are conducted on both smooth specimens and those with varing V-notch radii. By using the finite element method，the distribution of the stress-strain field at the notch is analyzed，the relationship between the stress-strain field and the notch strength，stress-rupture time，fatigue life and fracture behaviour of TA15 titanium alloy are further investigated. The results show that under static loading，as the notch radius decreases from 0.85 mm to 0.15 mm，both the tensile strength and stress-rupture time of TA15 titanium alloy increase，while the proportion of the shear-plastic zone in fracture decreases. Stress triaxiality around the notch initially increases and then decreases as it extends inward from the root of the notch，as determined by finite element analysis. The fracture originates from the peak position of stress triaxiality （near the notch root）. During the prolonged stress-rupture tests，stress redistribution around the notch occurrs，resulting in a strengthening effect at the notch. Under dynamic loading，the fracture surface of the notched specimen exhibits multi-source crack propagation. Different stress concentrations and gradients around the notch result in varying degrees of fatigue damage. As the notch radius decreases，the size of the critical fatigue damage area decreases，effective stress increases，leading to a decrease in fatigue life and the proportion of crack propagation zones.
Austenite reversion heat treatment is a proven strategy for enhancing the mechanical properties of 300M steel； however， the phase transformation mechanisms governing austenite evolution during this process remain inadequately understood. This study employs in-situ electron backscatter diffraction （EBSD） to systematically investigate the microstructural evolution and crystallographic characteristics of 300M steel during high-temperature austenite reversion. Results demonstrate that during isothermal holding above the austenitizing temperature， martensite transforms into two distinct austenite morphologies： needle-shaped austenite （γ（A））， which retains the orientation of the original martensite， and spherical austenite （γ（G）） with a random orientation. Notably， γ（A） preferentially nucleates and grows within the grains， maintaining a Kurdjumov-Sachs （K-S） orientation relationship with the surrounding martensitic blocks. Consequently， most of the γ（A） phase shares the same orientation and size as the initial austenite phase， hindering the refinement of the final microstructure. In contrast， γ（G） has a small grain size and nucleates at the grain boundaries of the original austenite as well as within the newly formed γ（A） crystals. γ（G） lacks a K-S orientation relationship with the untransformed martensite and adopts a random orientation， playing a crucial role in refining the final microstructure. Furthermore， heating temperature and duration exhibit significant control over the completeness of martensite-to-austenite transformation， with γ（G） propagating into the matrix via diffusion-driven growth kinetics. These findings elucidate the dual-phase transformation pathways and their distinct roles in microstructural evolution， offering a mechanistic foundation for optimizing heat treatment protocols to achieve tailored microstructures in 300M steel.
The service performance and operation life of thermal barrier coatings are closely related to the phase composition and structure of the bond coat alloy， which is directly determined by its composition. In this work， the effects of the basic elements Co and Al and the modified element Zr on the precipitation behavior of equilibrium phases are analyzed by Thermo-Calc software. Then， the influence of Zr content on phase composition and Zr-rich phase distribution of NiCoCrAlY bond coat alloy is investigated using an X-ray diffractometer and a field emission scanning electron microscope. Thermodynamic calculation results show that the σ-CoCr phase begins to precipitate in the alloy with 10%（mass fraction， the same below）Co， and the maximum precipitation amount （mole fraction） of σ-CoCr phase increases from 0.055 to 0.229 when the Co content increases from 10% to 16%， and it exists in the high-temperature service range of coatings with Co content exceeding 14%. When the Al content is 8%-10%， the γ-Ni phase precipitates from the liquid before the β-NiAl phase， which is opposite in the alloys containing 12%-16%Al. Moreover， with the increase of Al content from 8% to 16%， the solidification interval significantly enlarges from 75 ℃ to 171 ℃， and the β-NiAl content continuously increases. When the Zr content increases from 0.15% to 1.0%， the liquidus temperature obviously decreases from 1264 ℃ to 1136 ℃， and the solidification temperature range enlarges from 151 ℃ to 275 ℃. In addition， the non-equilibrium phase composition at room temperature of the bond coat alloy designed based on thermodynamic calculation is composed of β-NiAl and γ'-Ni3Al matrix phases， and a small amount of α-Cr precipitate on the matrix. Meanwhile， Ni5Y is distributed surrounding γ'-Ni3Al phase. For the alloy containing 0.5% and 1.0%Zr， the precipitation position of H_L21 phase is different. This Zr-rich phase mainly precipitates at the interface of β-NiAl/γ'-Ni3Al for the former， while it also precipitates on the β-NiAl matrix phase for the latter.
To improve the service temperature of high-temperature components in engines and search for high-temperature resistant and high thermal insulation thermal barrier coating materials to replace YSZ， a high entropy rare earth zirconate ceramic material is designed based on a multi-element rare earth doping modification strategy， combined with the phase structure formation law， size disorder， and thermal conductivity theory of rare earth zirconate. The A-site high entropy of rare earth zirconate is synthesized using solid-phase synthesis method to prepare two high entropy ceramic materials （Sm0.2Gd0.2Eu0.2Lu0.2Dy0.2）2Zr2O7. The microstructure， phase stability， and thermal physical properties of high entropy ceramic materials are studied. The results indicate that （Sm0.2Gd0.2Eu0.2Lu0.2Dy0.2）2Zr2O7 ceramic material has a defect fluorite structure， a dense ceramic material structure， no obvious defects， and the synthesized ceramic material configuration entropy shows that it belongs to a high entropy system； after sintering at 1400 ℃， the （Sm0.2Gd0.2Eu0.2Lu0.2Dy0.2）2Zr2O7 ceramic material shows no significant grain growth， no precipitation of single oxides phases， and exhibits good high-temperature stability； at 1000 ℃ and 1200 ℃， the thermal conductivity of （Sm0.2Gd0.2Eu0.2Lu0.2Dy0.2）2Zr2O7 ceramic material is 1.781 W·m-1·K-1 and 2.056 W·m-1·K-1， respectively. Compared with conventional rare earth zirconate and YSZ materials， it has lower thermal conductivity and is a promising material for ultra-high temperature thermal barrier coatings.
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Founded in 1956 (monthly) ISSN 1001-4381 CN 11-1800/TB Sponsored by AECC Beijing Institute of Aeronautical Materials |
