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1CHALLENGE AND DEVELOPEMENT TRENDS TO FUTURE AERO ENGINE MATERIALS
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2Development of advanced polymer composites
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3Progress on Electrically Conductive Silicone Rubber
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4Review and prospect on developments of cast superalloys
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5Damage characterization and failure analysis in fiber reinforced composites
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6Strengthening mechanisms of metal matrix composites
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7POLYMERS OBTAINED FROM BENZOCYCLOBUTENES
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8Investigation on Indentation Creep by Depth Sensing Indentation
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9Study on In-Plane Anisotropy of 2524 Aluminum Alloy Sheet
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10Control and relief of residual stresses in high-strength aluminum alloy parts for aerospace industry
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11Study on Fatigue Performance of 7075-T651 Aluminum Alloys
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12Development and Application of P/M Superalloy
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13Development of honeycomb cell structure and materials
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14High-temperature polyimide composites and its application in aeronautical engine
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15Progress on Self-Healing Silicon Carbide Ceramic Matrix Composites and Its Applications
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16Progress of Advanced Near Net-Shape Investment Casting Technology of Superalloys
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1Microstructure and mechanical properties of ultra-high strength TiCp/Mg-1.4Zn-2.6Ca-0.5Mn nanocomposite after hot extrusion
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2Resent development in high-entropy alloys and other high-entropy materials
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3Method on measuring fibre permeabilities in resin transfer molding
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4Recent Process and Application of Electrochromism
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5Research Process in Plasma Spray Physical Vapor Deposited Thermal Barrier Coatings
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6First-principle Calculations of Mechanical Properties of Al2Cu, Al2CuMg and MgZn2 Intermetallics in High Strength Aluminum Alloys
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7Research Progress and Application Perspectives of 4D Printing
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8Research Progress in Preparation and Crystallization Technologies of Amorphous ITO Film
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9Novel Ceramic Materials for Thermal Barrier Coatings
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10Application and Research Status of Alternative Materials for 3D-printing Technology
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11Additive Manufacture of Metamaterials: a Review
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12Effect of Rare Earth Y on Microstructure and Properties of Sn-58Bi Solder Alloy
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13Research Progress in Cemented Carbide with Co-Ni-Al Composite Binder Phase
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14Effect of Filler Systems on Properties of Fluororubber Vulcanized by Peroxide
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15Effect of sintering temperature on microstructure and mechanical behavior of alumina-based ceramic shell by SLS
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16Research Progress of Metal-Intermetallic Laminated Composites
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Available online
, doi: 10.11868/j.issn.1005-5053.2020.000189
Abstract:
The spherical FeSiAl alloy powder was used as the raw material absorbent, and the flakes were made by extrusion under the action of ball milling to obtain excellent low-frequency adsorbing performance. The phase composition, microstructure and electromagnetic characteristics of the flaky FeSiAl alloy were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and vector network analyzer (VNA), the microwave absorption performance was studied. The results indicate that the absorption peaks of FeSiAl alloy absorbent are located in X and Ku bands. The flaky FeSiAl alloy containing 70%(mass fraction)as filler with the thickness of 4.00 mm exhibits strong dielectric and magnetic losses as well as a good impedance matching property. It displays extremely strong electromagnetic wave absorption with reflection loss of -32.8 dB at 2.25 GHz, and the low frequency wave absorbing performance is improved significantly compared with spherical FeSiAl alloy,.
The spherical FeSiAl alloy powder was used as the raw material absorbent, and the flakes were made by extrusion under the action of ball milling to obtain excellent low-frequency adsorbing performance. The phase composition, microstructure and electromagnetic characteristics of the flaky FeSiAl alloy were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and vector network analyzer (VNA), the microwave absorption performance was studied. The results indicate that the absorption peaks of FeSiAl alloy absorbent are located in X and Ku bands. The flaky FeSiAl alloy containing 70%(mass fraction)as filler with the thickness of 4.00 mm exhibits strong dielectric and magnetic losses as well as a good impedance matching property. It displays extremely strong electromagnetic wave absorption with reflection loss of -32.8 dB at 2.25 GHz, and the low frequency wave absorbing performance is improved significantly compared with spherical FeSiAl alloy,.
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Available online
, doi: 10.11868/j.issn.1005-5053.2020.000163
Abstract:
The fiber metal laminate is mainly used in the fuselage wall board, wing skin and other key parts of the aircraft. The structural parts mentioned above bear a large bending moment during the service, which requires that the fiber metal laminate should have the ability to resist bending deformation. In this study, fiber rare earth magnesium alloy super hybrid laminate, a new type of fuselage structure material was used as the research object. Three-point bending was used to test the bending strength of unidirectional and cross-ply rare earth magnesium alloy super hybrid laminates under different span-to-thickness ratios (L/h). SEM was used to observe the bending failure morphology of the laminate, and the progressive damage behavior of the laminate during the bending process was analyzed with finite element simulation. The research results show that the different L/h values have a certain effect on the bending strength of rare earth magnesium alloy super hybrid laminates. The effective bending failure L/h values of unidirectional and orthogonal rare earth magnesium alloy super hybrid laminates are 16-22 and 16-20 respectively. Through SEM observation and finite element analysis, it is concluded that the bending failure modes of laminate include elastic stage, plastic stage, fiber and epoxy resin matrix fracture stage, rare earth magnesium alloy fracture stage and laminate delamination stage.
The fiber metal laminate is mainly used in the fuselage wall board, wing skin and other key parts of the aircraft. The structural parts mentioned above bear a large bending moment during the service, which requires that the fiber metal laminate should have the ability to resist bending deformation. In this study, fiber rare earth magnesium alloy super hybrid laminate, a new type of fuselage structure material was used as the research object. Three-point bending was used to test the bending strength of unidirectional and cross-ply rare earth magnesium alloy super hybrid laminates under different span-to-thickness ratios (L/h). SEM was used to observe the bending failure morphology of the laminate, and the progressive damage behavior of the laminate during the bending process was analyzed with finite element simulation. The research results show that the different L/h values have a certain effect on the bending strength of rare earth magnesium alloy super hybrid laminates. The effective bending failure L/h values of unidirectional and orthogonal rare earth magnesium alloy super hybrid laminates are 16-22 and 16-20 respectively. Through SEM observation and finite element analysis, it is concluded that the bending failure modes of laminate include elastic stage, plastic stage, fiber and epoxy resin matrix fracture stage, rare earth magnesium alloy fracture stage and laminate delamination stage.
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Available online
, doi: 10.11868/j.issn.1005-5053.2020.000161
Abstract:
Solid propellant is an important source of power for rockets and missiles, and its performance improvement is of great significance for improving the combat capability of missile weapons. 3D printing technology as a focus on advanced manufacturing technology, able to complete high-precision, high-complexity device manufacturing that is difficult to achieve by traditional manufacturing processes, solve the problems of uneven mixing, poor product consistency, and low safety, which are difficult to solve by traditional solid propellant pouring process, has broad prospects in the field of solid propellant manufacture.. The slow progress of the research on the preparation of solid propellant by 3D printing is mainly due to the two major problems of safety and process bottleneck. In view of the safety issues of solid propellant 3D printing, solid propellant 3D printing and related work are divided into three stages: 3D printing of partial energetic components, 3D printing of mixed propellants, and 3D printing of solid propellants. The safe printability of energetic components should be demonstrated step by step. In review of the bottleneck problem of solid propellant 3D printing process, the development progress of 3D printing propellant special slurry and equipment is introduced. From the current achievements and development, the future research on solid propellant 3D printing should focus on the development of special formulation and the realization of large-scale printing.
Solid propellant is an important source of power for rockets and missiles, and its performance improvement is of great significance for improving the combat capability of missile weapons. 3D printing technology as a focus on advanced manufacturing technology, able to complete high-precision, high-complexity device manufacturing that is difficult to achieve by traditional manufacturing processes, solve the problems of uneven mixing, poor product consistency, and low safety, which are difficult to solve by traditional solid propellant pouring process, has broad prospects in the field of solid propellant manufacture.. The slow progress of the research on the preparation of solid propellant by 3D printing is mainly due to the two major problems of safety and process bottleneck. In view of the safety issues of solid propellant 3D printing, solid propellant 3D printing and related work are divided into three stages: 3D printing of partial energetic components, 3D printing of mixed propellants, and 3D printing of solid propellants. The safe printability of energetic components should be demonstrated step by step. In review of the bottleneck problem of solid propellant 3D printing process, the development progress of 3D printing propellant special slurry and equipment is introduced. From the current achievements and development, the future research on solid propellant 3D printing should focus on the development of special formulation and the realization of large-scale printing.
2021, 41(3): 1 -10
doi: 10.11868/j.issn.1005-5053.2021.000072
Abstract:
Carbon/carbon (C/C) composites have broad application prospects in aviation, aerospace and other fields because of their unique performance advantages at high temperature, but the oxidation sensitivity at high temperature has become the biggest bottleneck in their application. Surface coating technology is internationally recognized as the most effective way to solve this problem. Among the anti-oxidation coating systems on the surface of C/C composite, the silicon-based ceramic coating is the most mature one in the present study. In this paper, according to the three most representative systems of SiC coating, MoSi2 based coating and ultra-high temperature ceramic modified silicon-based ceramic coating, the coating preparation method, composition design, anti-oxidation mechanism and research progress at home and abroad were respectively reviewed. The existing problems of silicon-based ceramic coating on C/C composites were discussed, and the development trend of this research direction in the future was also put forward.
Carbon/carbon (C/C) composites have broad application prospects in aviation, aerospace and other fields because of their unique performance advantages at high temperature, but the oxidation sensitivity at high temperature has become the biggest bottleneck in their application. Surface coating technology is internationally recognized as the most effective way to solve this problem. Among the anti-oxidation coating systems on the surface of C/C composite, the silicon-based ceramic coating is the most mature one in the present study. In this paper, according to the three most representative systems of SiC coating, MoSi2 based coating and ultra-high temperature ceramic modified silicon-based ceramic coating, the coating preparation method, composition design, anti-oxidation mechanism and research progress at home and abroad were respectively reviewed. The existing problems of silicon-based ceramic coating on C/C composites were discussed, and the development trend of this research direction in the future was also put forward.
2021, 41(3): 11 -24
doi: 10.11868/j.issn.1005-5053.2021.000071
Abstract:
Carbon/carbon (C/C) composite has become a good candidate as an ultra-high temperature structural material for thermal structure in aerospace and other fields due to its low density and high temperature mechanical properties. However, conventional C/C composites cannot meet the application requirements of sharp thin-wall structure, because the pyrolytic carbon matrix is brittle and the single micron carbon fiber cannot effectively enhance the sharp thin-walled area. This paper reviews the preparation methods of nanotube/nanowire reinforced C/C composites and their effects on the structure and properties of the composites. The development status of introducing carbon nanotubes (CNTs), silicon carbide nanowires (SiCNWs) and hafnium carbide nanowires (HfCNWs) on the mechanical and ablative properties of C/C composites, as well as the toughening mechanism and ablation resistance mechanism of the composites are summarized. In view of the shortcomings of the composition, method and single test performance of the nano-reinforced material introduced at present, it is proposed to further improve and innovate the process technology on the base of these studies, and conduct reasonable component and structure design, so as to deeply study the high temperature mechanical properties and toughening mechanism of multi-scale toughened C/C composites.
Carbon/carbon (C/C) composite has become a good candidate as an ultra-high temperature structural material for thermal structure in aerospace and other fields due to its low density and high temperature mechanical properties. However, conventional C/C composites cannot meet the application requirements of sharp thin-wall structure, because the pyrolytic carbon matrix is brittle and the single micron carbon fiber cannot effectively enhance the sharp thin-walled area. This paper reviews the preparation methods of nanotube/nanowire reinforced C/C composites and their effects on the structure and properties of the composites. The development status of introducing carbon nanotubes (CNTs), silicon carbide nanowires (SiCNWs) and hafnium carbide nanowires (HfCNWs) on the mechanical and ablative properties of C/C composites, as well as the toughening mechanism and ablation resistance mechanism of the composites are summarized. In view of the shortcomings of the composition, method and single test performance of the nano-reinforced material introduced at present, it is proposed to further improve and innovate the process technology on the base of these studies, and conduct reasonable component and structure design, so as to deeply study the high temperature mechanical properties and toughening mechanism of multi-scale toughened C/C composites.
2021, 41(3): 25 -35
doi: 10.11868/j.issn.1005-5053.2021.000052
Abstract:
Continuous silicon carbide (SiC) fiber toughened SiC/SiC composites are composed of continuous SiC tows, interphase and SiC matrix. They possess a series of excellent properties such as high strength, high stiffness, low density, high-temperature resistance and oxidation resistance. They are the ideal materials for hot-section components of aero engines and land-based gas turbines. Under the influence of load, heat, vapor and oxidants, as well as the impact of gas and foreign matter, SiC/SiC composites have complex rupture and erosion failure modes. As SiC/SiC composites are being applied more extensively, the research on the failure mechanism because of fatigue and creep is becoming more and more important. The application of new characterization methods, such as acoustic emission, digital image correlation, electric resistance monitoring, in-situ CT and SEM on the SiC/SiC composites in recent years could facilitate the illumination of the damage evolution and failure mechanism during mechanism tests.
Continuous silicon carbide (SiC) fiber toughened SiC/SiC composites are composed of continuous SiC tows, interphase and SiC matrix. They possess a series of excellent properties such as high strength, high stiffness, low density, high-temperature resistance and oxidation resistance. They are the ideal materials for hot-section components of aero engines and land-based gas turbines. Under the influence of load, heat, vapor and oxidants, as well as the impact of gas and foreign matter, SiC/SiC composites have complex rupture and erosion failure modes. As SiC/SiC composites are being applied more extensively, the research on the failure mechanism because of fatigue and creep is becoming more and more important. The application of new characterization methods, such as acoustic emission, digital image correlation, electric resistance monitoring, in-situ CT and SEM on the SiC/SiC composites in recent years could facilitate the illumination of the damage evolution and failure mechanism during mechanism tests.
2021, 41(3): 36 -51
doi: 10.11868/j.issn.1005-5053.2021.000048
Abstract:
Carbon-based nanosensors have been widely used in the field of health monitoring of composite materials because of their excellent electromechanical sensing properties and embedded in composite materials by various deposition methods. This paper introduces the sensing mechanism and deposition methods of carbon-based nanosensors, including dip coating, spray coating, chemical vapor deposition, electrophoretic deposition and intercalation.The application of carbon-based nanosensor in the monitoring of composite manufacturing process, including various monitoring parameters in the process of composite manufacturing, such as enhanced compaction response, flow front tracking, resin cementation and curing is reviewed; and the progress in damage monitoring of composite structures under static and dynamic loads in the form of tensile, bending, compression or impact loading by using carbon- based nanosensors is described. Finally, the future research directions of carbon nanosensors in the field of structural health monitoring are discussed. The new 2D materials and their mixtures for the next generation of intelligent sensors are mainly introduced.
Carbon-based nanosensors have been widely used in the field of health monitoring of composite materials because of their excellent electromechanical sensing properties and embedded in composite materials by various deposition methods. This paper introduces the sensing mechanism and deposition methods of carbon-based nanosensors, including dip coating, spray coating, chemical vapor deposition, electrophoretic deposition and intercalation.The application of carbon-based nanosensor in the monitoring of composite manufacturing process, including various monitoring parameters in the process of composite manufacturing, such as enhanced compaction response, flow front tracking, resin cementation and curing is reviewed; and the progress in damage monitoring of composite structures under static and dynamic loads in the form of tensile, bending, compression or impact loading by using carbon- based nanosensors is described. Finally, the future research directions of carbon nanosensors in the field of structural health monitoring are discussed. The new 2D materials and their mixtures for the next generation of intelligent sensors are mainly introduced.
2021, 41(3): 52 -65
doi: 10.11868/j.issn.1005-5053.2021.000018
Abstract:
The transmission shaft is one of the key components of the helicopter transmission system. It is an inevitable trend to replace metal transmission shaft with composite transmission shaft. This article mainly focused on the structural design, manufacturing technology, and connection mode of the helicopter composite driveshaft. In addition, the future development direction and trend of helicopter composite transmission shaft technology were put forward for the existing problems. At present, the structural design of composite transmission shaft includes theoretical design method and finite element design method, the manufacturing technology includes winding forming, 3D braiding VRTM forming and autoclave forming, etc, and the connection modes included mechanical joint, adhesive bonded joint, and hybrid joint, etc. Significantly, the existing mainstream design methods of composite transmission shaft are inefficient and subjective. In future research, the combination of artificial intelligence algorithm and finite element analysis technology can be adopted to automatically solve the optimal design scheme within the boundary conditions on the premise of meeting the use requirements. Simultaneously, the current composite shaft tube has the disadvantages of poor interlaminar properties. It is suggested that the recyclable thermoplastic composite with high toughness, good fatigue resistance, and impact resistance should be preferred in the preparation of shaft tubes and realize in-situ consolidation. In this way, the mechanical properties, environmental compatibility, and preparation efficiency of the composite transmission shaft can be improved. Besides, the traditional connection modes have different shortcomings. By applying pre-tightened teeth connection technology and high tension winding technology, the existing teeth press-fitting connection should be ameliorated to improve the structural bearing capacity and ligation efficiency of the composite driveshaft, so as to ensure the stable and safe operation of the helicopter transmission system.
The transmission shaft is one of the key components of the helicopter transmission system. It is an inevitable trend to replace metal transmission shaft with composite transmission shaft. This article mainly focused on the structural design, manufacturing technology, and connection mode of the helicopter composite driveshaft. In addition, the future development direction and trend of helicopter composite transmission shaft technology were put forward for the existing problems. At present, the structural design of composite transmission shaft includes theoretical design method and finite element design method, the manufacturing technology includes winding forming, 3D braiding VRTM forming and autoclave forming, etc, and the connection modes included mechanical joint, adhesive bonded joint, and hybrid joint, etc. Significantly, the existing mainstream design methods of composite transmission shaft are inefficient and subjective. In future research, the combination of artificial intelligence algorithm and finite element analysis technology can be adopted to automatically solve the optimal design scheme within the boundary conditions on the premise of meeting the use requirements. Simultaneously, the current composite shaft tube has the disadvantages of poor interlaminar properties. It is suggested that the recyclable thermoplastic composite with high toughness, good fatigue resistance, and impact resistance should be preferred in the preparation of shaft tubes and realize in-situ consolidation. In this way, the mechanical properties, environmental compatibility, and preparation efficiency of the composite transmission shaft can be improved. Besides, the traditional connection modes have different shortcomings. By applying pre-tightened teeth connection technology and high tension winding technology, the existing teeth press-fitting connection should be ameliorated to improve the structural bearing capacity and ligation efficiency of the composite driveshaft, so as to ensure the stable and safe operation of the helicopter transmission system.
2021, 41(3): 66 -82
doi: 10.11868/j.issn.1005-5053.2021.000028
Abstract:
Technologies related with infrared radiation (IR) detection and IR stealth have been wildly applied in the modern military field. IR signal of weapons such as aircraft is more prominent with the performance improving. Meanwhile, The detection ratio and sensitivity of the third generation of IR detector based on the photoelectric effect are greatly improved. Therefore, IR stealth technology becomes a necessary means to improve the survivability and combat effectiveness of the battlefield. In this paper, based on the IR characteristics of the aircraft, the IR signal distribution and effect factors are analyzed, the operating principles, detection performance and development trend of the third generation IR detector materials presented by HgCdTe are summarized, the application status of low emissivity coating in the field of infrared stealth is introduced, the stealth mechanism and research progress of various emerging materials are reviewed. Finally, the future research directions of materials for IR detection and IR stealth are prospected in accordance with the service requirement.
Technologies related with infrared radiation (IR) detection and IR stealth have been wildly applied in the modern military field. IR signal of weapons such as aircraft is more prominent with the performance improving. Meanwhile, The detection ratio and sensitivity of the third generation of IR detector based on the photoelectric effect are greatly improved. Therefore, IR stealth technology becomes a necessary means to improve the survivability and combat effectiveness of the battlefield. In this paper, based on the IR characteristics of the aircraft, the IR signal distribution and effect factors are analyzed, the operating principles, detection performance and development trend of the third generation IR detector materials presented by HgCdTe are summarized, the application status of low emissivity coating in the field of infrared stealth is introduced, the stealth mechanism and research progress of various emerging materials are reviewed. Finally, the future research directions of materials for IR detection and IR stealth are prospected in accordance with the service requirement.
2021, 41(3): 83 -95
doi: 10.11868/j.issn.1005-5053.2021.000046
Abstract:
Due to the high energy density, long cycling life, excellent Coulombic efficiency, wide working temperature range and low operation cost, Lithium-ion battery (LIB) is widely regarded as one of the most promising candidates for energy storage systems. At present time, LIB has been used in mobile phones, notebook computers, electric vehicles and other consumer fields, but also in civil aircraft, unmanned aerial vehicles, space detectors and the aerospace fields have a broad application prospect. In order to further expand the application field of LIB, a large number of research teams have designed and developed a wide variety of electrode materials with excellent performance for LIB through ingenious ideas. Through in-depth research, the electrolyte with wide temperature adaptability and high pressure adaptability is developed. To further explore and develop LIB with improved property, much research effort has been devoted into this field. After 30 years of technological breakthrough and industrial promotion, LIB-related products have become increasingly mature, and have been widely used in various fields in order to further broaden the application scenarios of LIB, the preparation of high-performance electrode materials and the construction of safe electrolyte system will be the new direction of the development of LIB technology.
Due to the high energy density, long cycling life, excellent Coulombic efficiency, wide working temperature range and low operation cost, Lithium-ion battery (LIB) is widely regarded as one of the most promising candidates for energy storage systems. At present time, LIB has been used in mobile phones, notebook computers, electric vehicles and other consumer fields, but also in civil aircraft, unmanned aerial vehicles, space detectors and the aerospace fields have a broad application prospect. In order to further expand the application field of LIB, a large number of research teams have designed and developed a wide variety of electrode materials with excellent performance for LIB through ingenious ideas. Through in-depth research, the electrolyte with wide temperature adaptability and high pressure adaptability is developed. To further explore and develop LIB with improved property, much research effort has been devoted into this field. After 30 years of technological breakthrough and industrial promotion, LIB-related products have become increasingly mature, and have been widely used in various fields in order to further broaden the application scenarios of LIB, the preparation of high-performance electrode materials and the construction of safe electrolyte system will be the new direction of the development of LIB technology.
2021, 41(3): 96 -110
doi: 10.11868/j.issn.1005-5053.2021.000053
Abstract:
High-temperature structural materials are the key materials of aeroengine. Nickel-based superalloys are widely used in the blades, turbine discs, combustion chambers and other hot parts of advanced jet engines. However, the impurities are inevitably introduced into nickel-based superalloys during the process of physical metallurgy, vacuum casting and so on. With the continuous improvement of the performance requirement of superalloy parts, the impacts of impurities on the properties of superalloys have been paid more and more attention. As one kind of terrible impurities, sulfur still has a tremendous negative impacts on the properties of materials although its concentration is extremely low. Through integrating the experimental and the first-principles studies, this work comprehensively reveals the effect of sulfur on the structural evolution of nickel-based superalloys and its segregation behavior at the interface of superalloy substrate, oxides layer and coating. Moreover, the contributions of sulfur to the mechanical properties, oxidation resistance, hot corrosion properties and the coating performance are summarized and discussed thoroughly.
High-temperature structural materials are the key materials of aeroengine. Nickel-based superalloys are widely used in the blades, turbine discs, combustion chambers and other hot parts of advanced jet engines. However, the impurities are inevitably introduced into nickel-based superalloys during the process of physical metallurgy, vacuum casting and so on. With the continuous improvement of the performance requirement of superalloy parts, the impacts of impurities on the properties of superalloys have been paid more and more attention. As one kind of terrible impurities, sulfur still has a tremendous negative impacts on the properties of materials although its concentration is extremely low. Through integrating the experimental and the first-principles studies, this work comprehensively reveals the effect of sulfur on the structural evolution of nickel-based superalloys and its segregation behavior at the interface of superalloy substrate, oxides layer and coating. Moreover, the contributions of sulfur to the mechanical properties, oxidation resistance, hot corrosion properties and the coating performance are summarized and discussed thoroughly.
2021, 41(3): 111 -119
doi: 10.11868/j.issn.1005-5053.2021.000055
Abstract:
The effects of over-aging degree on the microstructure, properties and fracture behavior of 7050 aluminum alloy at different temperatures were investigated by means of room temperature/high temperature tensile, SEM and TEM. The results show that the fracture behavior of 7050 aluminum alloy at room temperature is determined by the degree of over-aging. With the deepening of the degree of over-aging, the fracture behavior changes from intergranular fracture to dimple fracture. The deeper the degree of over-aging, the more dimples and the larger the number of dimples. Both the degree of over-aging and tensile temperature have effects on the tensile properties and fracture behavior of 7050 aluminum alloy at high temperature. When the tensile temperature is not higher than 150 ℃, the strength of the alloys with different over-aging degrees decreases to the same extent, and the temperature is the main factor determining the tensile strength. When the tensile temperature is increased to 175 ℃, the strength of the alloy in the deeply over-aged T73 decreases more than that in the lightly over-aged T76, and the effect of aging degree on the strength increases to some extent. In the range of 125 ℃ to 175 ℃, the fracture of the deeply over-aged alloy turns into a dimple fracture dominated by the second phase/matrix interface sliding earlier than that of the lightly over-aged alloy.
The effects of over-aging degree on the microstructure, properties and fracture behavior of 7050 aluminum alloy at different temperatures were investigated by means of room temperature/high temperature tensile, SEM and TEM. The results show that the fracture behavior of 7050 aluminum alloy at room temperature is determined by the degree of over-aging. With the deepening of the degree of over-aging, the fracture behavior changes from intergranular fracture to dimple fracture. The deeper the degree of over-aging, the more dimples and the larger the number of dimples. Both the degree of over-aging and tensile temperature have effects on the tensile properties and fracture behavior of 7050 aluminum alloy at high temperature. When the tensile temperature is not higher than 150 ℃, the strength of the alloys with different over-aging degrees decreases to the same extent, and the temperature is the main factor determining the tensile strength. When the tensile temperature is increased to 175 ℃, the strength of the alloy in the deeply over-aged T73 decreases more than that in the lightly over-aged T76, and the effect of aging degree on the strength increases to some extent. In the range of 125 ℃ to 175 ℃, the fracture of the deeply over-aged alloy turns into a dimple fracture dominated by the second phase/matrix interface sliding earlier than that of the lightly over-aged alloy.
2021, 41(3): 120 -125
doi: 10.11868/j.issn.1005-5053.2021.000070
Abstract:
Hardness, conductivity, tension testing and fracture toughness of a new aluminum plate with thickness of 230 mm were investigated when ageing at different time during 155~175 ℃. The microstructure characteristics of the alloy under different aging processes were studied by TEM. The results show that the optimal aging system of T7451 for the super thick aluminum alloy plate is 155 ℃ for 24 h. Under these conditions, the yield strength, tension strength and elongation of the alloy are 448 MPa, 512 MPa and 7.6% respectively. The fracture toughness in L-T direction is 29.8 MPa·m1/2 and the electrical conductivity is 41.6%IACS . At this point the main precipitation is η' phase and η phase. Aging temperature is the main factor affecting the density and size of precipitated phase. The higher the ageing temperature is, the greater the driving force of precipitated phase is, the larger the size of precipitated phase is, the higher the electrical conductivity and the lower the strength are. The decrease of the strength difference between the matrix and grain boundary is the main reason for the increase of fracture toughness of the alloy under over-aged condition.
Hardness, conductivity, tension testing and fracture toughness of a new aluminum plate with thickness of 230 mm were investigated when ageing at different time during 155~175 ℃. The microstructure characteristics of the alloy under different aging processes were studied by TEM. The results show that the optimal aging system of T7451 for the super thick aluminum alloy plate is 155 ℃ for 24 h. Under these conditions, the yield strength, tension strength and elongation of the alloy are 448 MPa, 512 MPa and 7.6% respectively. The fracture toughness in L-T direction is 29.8 MPa·m1/2 and the electrical conductivity is 41.6%IACS . At this point the main precipitation is η' phase and η phase. Aging temperature is the main factor affecting the density and size of precipitated phase. The higher the ageing temperature is, the greater the driving force of precipitated phase is, the larger the size of precipitated phase is, the higher the electrical conductivity and the lower the strength are. The decrease of the strength difference between the matrix and grain boundary is the main reason for the increase of fracture toughness of the alloy under over-aged condition.
2021, 41(3): 126 -132
doi: 10.11868/j.issn.1005-5053.2021.000063
Abstract:
The effects of Si, S and Zr on the microstructure and mechanical properties of directionally solidified superalloy DZ125 were studied. The results showed that S formed M2SC compound growing with MC carbides together in DZ125 alloy, and S was also rich in carbides and grain boundary. Si mainly distributed in carbides in grain boundary. When Zr content in DZ125 alloy is up to 0.044 % (mass fraction), Zr participated the formation of M2SC, which have about 6 % Zr. In the scope of research, Si, S and Zr hadn’t obvious effect on the tensile properties at room temperature of DZ125 alloy. However, they had harmful influence on the stress rupture properties, when their content in the alloy increased to some high level, the stress rupture lives under 760 ℃/804 MPa were degraded about 50%. And the stress rupture lives under 980 ℃/235 MPa decreased slowly with the content of Si, S and Zr. The deterioration of stress rupture properties was due to the formation of M2SC, the enrichment of S and Si in carbides and grain boundary, as well as the decline of cuboidal content of γ'phase in the dendrite regions. Therefore, the content of Si, S and Zr should be kept to low level relatively, in order to ensure DZ125 alloy have good mechanical properties.
The effects of Si, S and Zr on the microstructure and mechanical properties of directionally solidified superalloy DZ125 were studied. The results showed that S formed M2SC compound growing with MC carbides together in DZ125 alloy, and S was also rich in carbides and grain boundary. Si mainly distributed in carbides in grain boundary. When Zr content in DZ125 alloy is up to 0.044 % (mass fraction), Zr participated the formation of M2SC, which have about 6 % Zr. In the scope of research, Si, S and Zr hadn’t obvious effect on the tensile properties at room temperature of DZ125 alloy. However, they had harmful influence on the stress rupture properties, when their content in the alloy increased to some high level, the stress rupture lives under 760 ℃/804 MPa were degraded about 50%. And the stress rupture lives under 980 ℃/235 MPa decreased slowly with the content of Si, S and Zr. The deterioration of stress rupture properties was due to the formation of M2SC, the enrichment of S and Si in carbides and grain boundary, as well as the decline of cuboidal content of γ'phase in the dendrite regions. Therefore, the content of Si, S and Zr should be kept to low level relatively, in order to ensure DZ125 alloy have good mechanical properties.
2021, 41(3): 133 -138
doi: 10.11868/j.issn.1005-5053.2021.000045
Abstract:
In order to study the absorbing properties of Jauman absorber, organic conductive coating material and polyurethane foam were used as resistive screen and isolation layer material respectively. The electromagnetic parameters of the resistive screen and the isolation foam material were tested. Firstly, the absorbing characteristics of Salisbury screen, including the influence of thickness of different resistance screens on the input impedance, reflection coefficient and reflectivity of the electromagnetic wave were studied, and then the input impedance and the influence of the thickness of the resistive screen on the reflection coefficient of the double-screen Jauman absorber were studied. The results show that when the thickness of the first layer of Salisbury screen is constant, the reflectivity of the material first decreases and then increases with the increase of the thickness of the second layer. For the double-screen Jauman absorber, when the thickness of the second layer is 72 μm and the thickness of the fourth layer is 11 μm, the absolute value |Γ| of the reflection coefficient is 0.00157, and the absorbing performance is the best. The bandwidth of reflectivity of double-screen Jauman absorber less than −10 dB is 13.1 GHz, and that of Salisbury screen less than −10 dB is 9.1 GHz, indicating that the bandwidth of double-screen Jauman absorber is significantly larger than that of Salisbury screen absorber.
In order to study the absorbing properties of Jauman absorber, organic conductive coating material and polyurethane foam were used as resistive screen and isolation layer material respectively. The electromagnetic parameters of the resistive screen and the isolation foam material were tested. Firstly, the absorbing characteristics of Salisbury screen, including the influence of thickness of different resistance screens on the input impedance, reflection coefficient and reflectivity of the electromagnetic wave were studied, and then the input impedance and the influence of the thickness of the resistive screen on the reflection coefficient of the double-screen Jauman absorber were studied. The results show that when the thickness of the first layer of Salisbury screen is constant, the reflectivity of the material first decreases and then increases with the increase of the thickness of the second layer. For the double-screen Jauman absorber, when the thickness of the second layer is 72 μm and the thickness of the fourth layer is 11 μm, the absolute value |Γ| of the reflection coefficient is 0.00157, and the absorbing performance is the best. The bandwidth of reflectivity of double-screen Jauman absorber less than −10 dB is 13.1 GHz, and that of Salisbury screen less than −10 dB is 9.1 GHz, indicating that the bandwidth of double-screen Jauman absorber is significantly larger than that of Salisbury screen absorber.
2021, 41(3): 139 -147
doi: 10.11868/j.issn.1005-5053.2021.000057
Abstract:
The titanium alloy-superalloy dissimilar material composite structure can give full play to the respective advantages of the two materials and achieve complementary performance, which has important application prospects in the field of aeroengine manufacturing. In this paper, the (V-15Cr)+0Cr13 intermediate layer structure was designed for TC4-GH4169 composite structure, and was prepared by laser melting deposition technology. The effects of the laser power and the powder stacking method on the metallurgical quality of the interface of the laser melting deposited TC4-GH4169 dissimilar material were studied. The results show that the interface metallurgical control of the (V-15Cr)+0Cr13 composite interlayer is a key factor affecting the metallurgical quality of TC4-GH4169. For the powder feeding laser melting deposition process, when the laser power is 400 W, there is no effective metallurgical reaction between 0Cr13 and V-15Cr due to the low laser energy, resulting in interlayer peeling; when the laser power is 600 W, a small amount of brittle σ phase appears at the interface of (V-15Cr)/0Cr13; when the laser power is increased to 800 W, there is a greater dilution ratio between the 0Cr13 and V-15Cr cladding layers, and the continuously distributed σ phase with a thickness of about 20 μm is formed at the interface. By using powder presetting laser melting deposition process and focusing the laser on the surface of the V-15Cr layer, the dilution ratio between the 0Cr13 and V-15Cr cladding layers can be controlled at a reasonable level, the formation of the σ phase at the interface can be effectively avoided. The shear test results show that the fracture occurs in the V-15Cr alloy layer. The interfacial strength reaches 299 MPa and the strength coefficient reaches 0.61.
The titanium alloy-superalloy dissimilar material composite structure can give full play to the respective advantages of the two materials and achieve complementary performance, which has important application prospects in the field of aeroengine manufacturing. In this paper, the (V-15Cr)+0Cr13 intermediate layer structure was designed for TC4-GH4169 composite structure, and was prepared by laser melting deposition technology. The effects of the laser power and the powder stacking method on the metallurgical quality of the interface of the laser melting deposited TC4-GH4169 dissimilar material were studied. The results show that the interface metallurgical control of the (V-15Cr)+0Cr13 composite interlayer is a key factor affecting the metallurgical quality of TC4-GH4169. For the powder feeding laser melting deposition process, when the laser power is 400 W, there is no effective metallurgical reaction between 0Cr13 and V-15Cr due to the low laser energy, resulting in interlayer peeling; when the laser power is 600 W, a small amount of brittle σ phase appears at the interface of (V-15Cr)/0Cr13; when the laser power is increased to 800 W, there is a greater dilution ratio between the 0Cr13 and V-15Cr cladding layers, and the continuously distributed σ phase with a thickness of about 20 μm is formed at the interface. By using powder presetting laser melting deposition process and focusing the laser on the surface of the V-15Cr layer, the dilution ratio between the 0Cr13 and V-15Cr cladding layers can be controlled at a reasonable level, the formation of the σ phase at the interface can be effectively avoided. The shear test results show that the fracture occurs in the V-15Cr alloy layer. The interfacial strength reaches 299 MPa and the strength coefficient reaches 0.61.
1998, 18(4): 52-61
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Address：P.Q.BOX 81-44,Beijing 100095,China
Telephone：010-62496277 E-mail：hkclxb@biam.ac.cn
Supported by Beijing Renhe Information Technology Co. LtdTechnical support：info@rhhz.net