Pub Date : 1900-01-01DOI: 10.18323/2782-4039-2022-2-74-83
D. Rastorguev, K. Semenov
A provision of location tolerances and their retention in the postoperative period is one of the main hard-hitting process tasks when producing long-length low-rigidity shaft-type parts. Mixed treatment – tensile straightening or thermal-power treatment is one of the technological methods intended to provide this group of geometrical indicators, including axle linearity. The efficiency improvement of this technology is impossible without knowing the features of the formation of plastic deformations distribution along the length of long-length blank parts. The paper considers the application of an optical method for controlling deformation on the surface using the method of digital image correlation at axial deformation of cylindrical parts. The work describes an experimental device for optic control of deformations when loading a specimen using digital cameras. The authors studied the influence of various modes of paint deposition to a sample (deposition rate, distance, deposition mode – continuous or pulsed) on the features of a produced speckle in the form of random distribution of mixed-size paint spots over the specimen surface; obtained histograms of the intensity distribution of various speckles. The authors carried out the experiments to identify deformations based on the technology of the local gradient digital image correlation method for the specimens of polymer tubes with different speckle types. The study identified the distribution of the deformation over the length of samples within the deformable area selected for analysis with the specified degree of smoothing provided by choice of correlation kernel size and the choice of its displacement step for fixing deformation processes with a precise error. The authors obtained distributions of axial deformations along the length of specimens and errors of deformations determination depending on a speckle nature. The study specifies necessary speckle parameters ensuring minimal error for long-length samples up to 200 mm in length and appropriate technology for paint depositing. It is a speckle with a wide range of spot sizes rarefied with their locations and the Gaussian filter image smoothing before the analysis.
{"title":"Identification of deformations of cylindrical specimens by optical method using the technique of digital image correlation","authors":"D. Rastorguev, K. Semenov","doi":"10.18323/2782-4039-2022-2-74-83","DOIUrl":"https://doi.org/10.18323/2782-4039-2022-2-74-83","url":null,"abstract":"A provision of location tolerances and their retention in the postoperative period is one of the main hard-hitting process tasks when producing long-length low-rigidity shaft-type parts. Mixed treatment – tensile straightening or thermal-power treatment is one of the technological methods intended to provide this group of geometrical indicators, including axle linearity. The efficiency improvement of this technology is impossible without knowing the features of the formation of plastic deformations distribution along the length of long-length blank parts. The paper considers the application of an optical method for controlling deformation on the surface using the method of digital image correlation at axial deformation of cylindrical parts. The work describes an experimental device for optic control of deformations when loading a specimen using digital cameras. The authors studied the influence of various modes of paint deposition to a sample (deposition rate, distance, deposition mode – continuous or pulsed) on the features of a produced speckle in the form of random distribution of mixed-size paint spots over the specimen surface; obtained histograms of the intensity distribution of various speckles. The authors carried out the experiments to identify deformations based on the technology of the local gradient digital image correlation method for the specimens of polymer tubes with different speckle types. The study identified the distribution of the deformation over the length of samples within the deformable area selected for analysis with the specified degree of smoothing provided by choice of correlation kernel size and the choice of its displacement step for fixing deformation processes with a precise error. The authors obtained distributions of axial deformations along the length of specimens and errors of deformations determination depending on a speckle nature. The study specifies necessary speckle parameters ensuring minimal error for long-length samples up to 200 mm in length and appropriate technology for paint depositing. It is a speckle with a wide range of spot sizes rarefied with their locations and the Gaussian filter image smoothing before the analysis.","PeriodicalId":251458,"journal":{"name":"Frontier materials & technologies","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129241808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.18323/2782-4039-2023-2-64-1
M. Ilyushkin, E. Kiselev
Polycrystalline composite materials made of carbon fiber reinforced plastics have more and more widespread application in mechanical engineering and become the main material for the production of modern types of high-speed transport. Thus, their share has already reached 35–45 % in the structural design of passenger aircrafts. However, the technology of machining surfaces of parts made of these materials, in particular, holes, is characterized by insufficient knowledge, the absence of regulatory standards for cutting modes and is most often based on the production experience of enterprises. When changing the processing conditions and the material, the pre-production engineering duration causes a significant increase in the cost of manufacturing parts due to the need for experimental selection of the cutting mode rational elements. To exclude the empirical selection of rational elements of the machining equipment cutting mode, the authors considered the possibility of using digital twins for studying the processes of drilling holes in the blanks made of composite materials, including those with the ultrasonic field energy introduction into the new surface shaping zone (to improve the processing quality and productivity). When modeling, the LS-DYNA program was used. The authors prepared the models and processed the results using the LS-PrePost 4.8 program. During the study, an explicit modeling method was used with preliminary validation and calibration of the results of tests of composites. The authors carried out calibration on test operations of tension, three-point bending, and interlaminar shear of the ВКУ-39 polymer composite material based on carbon fibers (carbon fiber reinforced plastic) widely used in domestic engineering. The developed finite element computer models allow simulating drilling procedures without carrying out rather complicated and expensive field tests. As a result of modeling, a simulation file was obtained, which reflects the process of drilling holes in a polymer composite material blank, as close as possible to the real-life situation with chip removal.
{"title":"Simulation of the processes of drilling polymer composite blanks using digital twins","authors":"M. Ilyushkin, E. Kiselev","doi":"10.18323/2782-4039-2023-2-64-1","DOIUrl":"https://doi.org/10.18323/2782-4039-2023-2-64-1","url":null,"abstract":"Polycrystalline composite materials made of carbon fiber reinforced plastics have more and more widespread application in mechanical engineering and become the main material for the production of modern types of high-speed transport. Thus, their share has already reached 35–45 % in the structural design of passenger aircrafts. However, the technology of machining surfaces of parts made of these materials, in particular, holes, is characterized by insufficient knowledge, the absence of regulatory standards for cutting modes and is most often based on the production experience of enterprises. When changing the processing conditions and the material, the pre-production engineering duration causes a significant increase in the cost of manufacturing parts due to the need for experimental selection of the cutting mode rational elements. To exclude the empirical selection of rational elements of the machining equipment cutting mode, the authors considered the possibility of using digital twins for studying the processes of drilling holes in the blanks made of composite materials, including those with the ultrasonic field energy introduction into the new surface shaping zone (to improve the processing quality and productivity). When modeling, the LS-DYNA program was used. The authors prepared the models and processed the results using the LS-PrePost 4.8 program. During the study, an explicit modeling method was used with preliminary validation and calibration of the results of tests of composites. The authors carried out calibration on test operations of tension, three-point bending, and interlaminar shear of the ВКУ-39 polymer composite material based on carbon fibers (carbon fiber reinforced plastic) widely used in domestic engineering. The developed finite element computer models allow simulating drilling procedures without carrying out rather complicated and expensive field tests. As a result of modeling, a simulation file was obtained, which reflects the process of drilling holes in a polymer composite material blank, as close as possible to the real-life situation with chip removal.","PeriodicalId":251458,"journal":{"name":"Frontier materials & technologies","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126606018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.18323/2782-4039-2022-4-102-112
A. N. Pautov, A. Medvedev, V. R. Galimov, O. Kolenchenko
Linear friction welding is an advanced technology for manufacturing titanium blisks for gas-turbine engine compressors, which are subjected to stringent requirements for cyclic strength and dimensional accuracy. Substitution of conventional butt joints with more technological T-shape joints is a promising area, which provides reducing of the pre-welding machining costs. The introduction of T-form joints requires additional research of thermal distribution specifics and strain-stress state formation in the welding process and after its end. Therefore, the study of residual stresses in titanium alloy T-shape joints produced by linear friction welding is topical. The paper investigates the residual stresses in imitating welded blisk joints. The authors consider the results of welding where the blade imitator has a reamed relief of a smaller section. The finite element model covering forging, cooling, and disassembly of welded specimens is offered. The authors developed the model in ANSYS Workbench to describe the strain-stress state of welded specimens, which allows for estimating the residual stress levels and spreading. The main distinctive feature of the model is an accounting of asymmetric temperature distribution obtained by finite-difference solving of a T-shape joint thermal problem and weld shape simulation obtained as a result of welded joints metallographic research. The presented model allows the evaluation of the residual stresses in joints. The distribution of residual stresses in T-shaped welded joints is specific – compressive stresses existing in a weld are balanced by tensile stresses acting at a distance of 1 mm from the joint. The formation of compressive stresses in a weld is caused by plastic deformation due to the forging force action.
{"title":"The influence of a workpiece shape on residual stresses during linear friction welding","authors":"A. N. Pautov, A. Medvedev, V. R. Galimov, O. Kolenchenko","doi":"10.18323/2782-4039-2022-4-102-112","DOIUrl":"https://doi.org/10.18323/2782-4039-2022-4-102-112","url":null,"abstract":"Linear friction welding is an advanced technology for manufacturing titanium blisks for gas-turbine engine compressors, which are subjected to stringent requirements for cyclic strength and dimensional accuracy. Substitution of conventional butt joints with more technological T-shape joints is a promising area, which provides reducing of the pre-welding machining costs. The introduction of T-form joints requires additional research of thermal distribution specifics and strain-stress state formation in the welding process and after its end. Therefore, the study of residual stresses in titanium alloy T-shape joints produced by linear friction welding is topical. The paper investigates the residual stresses in imitating welded blisk joints. The authors consider the results of welding where the blade imitator has a reamed relief of a smaller section. The finite element model covering forging, cooling, and disassembly of welded specimens is offered. The authors developed the model in ANSYS Workbench to describe the strain-stress state of welded specimens, which allows for estimating the residual stress levels and spreading. The main distinctive feature of the model is an accounting of asymmetric temperature distribution obtained by finite-difference solving of a T-shape joint thermal problem and weld shape simulation obtained as a result of welded joints metallographic research. The presented model allows the evaluation of the residual stresses in joints. The distribution of residual stresses in T-shaped welded joints is specific – compressive stresses existing in a weld are balanced by tensile stresses acting at a distance of 1 mm from the joint. The formation of compressive stresses in a weld is caused by plastic deformation due to the forging force action.","PeriodicalId":251458,"journal":{"name":"Frontier materials & technologies","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129245854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.18323/2782-4039-2022-2-17-27
A. Denisenko, R. Grishin
A reasonable choice of machine layout is one of the ways to improve the quality of CNC machines and the result of a comprehensive analysis and consideration of many frequently conflicting requirements: accuracy, design feasibility, processability, productiveness, efficiency, safety, etc. The complexity of the choice of machine layout is associated with their diversity depending on the fact that machines with different designs of assembly units can have the same arrangement and, conversely, lathes with the same designs of main elements can have different layouts. Due to the multiple effects of layout on the accuracy characteristics of a machine, the optimal layout solution choice is the priority problem of machine building. The study covers the development of a technique for selecting a layout solution for the CNC lathes, which considers the random location of cutting zones and the existence of power factors related to the design and layout of a spindle unit. In the developed technique, as a criterion for choosing an optimal arrangement, the authors suggest using an accuracy layout criterion evaluated by the elastic deformations of a spindle in the cutting zone. The study resulted in analytical expressions for an objective function depending on two design variables: angles determining the location of a spindle pre-drive gear and a tool-holding group. The authors note that for the precision lathes when identifying spindle bearing radial stiffness, one should take into account the stiffness anisotropy of a housing bore for the spindle front support. For two specified design variables, the study shows the performance of a scanning method (complete enumeration for 322 points). Using this method and processing with Mathcad software, the authors obtained a possible variation range of values of specified angles for five standard layouts of spindle support bearings and limitations related to the minimization of elastic deformations of the tooling system.
{"title":"Optimizing the layout of a CNC lathe","authors":"A. Denisenko, R. Grishin","doi":"10.18323/2782-4039-2022-2-17-27","DOIUrl":"https://doi.org/10.18323/2782-4039-2022-2-17-27","url":null,"abstract":"A reasonable choice of machine layout is one of the ways to improve the quality of CNC machines and the result of a comprehensive analysis and consideration of many frequently conflicting requirements: accuracy, design feasibility, processability, productiveness, efficiency, safety, etc. The complexity of the choice of machine layout is associated with their diversity depending on the fact that machines with different designs of assembly units can have the same arrangement and, conversely, lathes with the same designs of main elements can have different layouts. Due to the multiple effects of layout on the accuracy characteristics of a machine, the optimal layout solution choice is the priority problem of machine building. The study covers the development of a technique for selecting a layout solution for the CNC lathes, which considers the random location of cutting zones and the existence of power factors related to the design and layout of a spindle unit. In the developed technique, as a criterion for choosing an optimal arrangement, the authors suggest using an accuracy layout criterion evaluated by the elastic deformations of a spindle in the cutting zone. The study resulted in analytical expressions for an objective function depending on two design variables: angles determining the location of a spindle pre-drive gear and a tool-holding group. The authors note that for the precision lathes when identifying spindle bearing radial stiffness, one should take into account the stiffness anisotropy of a housing bore for the spindle front support. For two specified design variables, the study shows the performance of a scanning method (complete enumeration for 322 points). Using this method and processing with Mathcad software, the authors obtained a possible variation range of values of specified angles for five standard layouts of spindle support bearings and limitations related to the minimization of elastic deformations of the tooling system.","PeriodicalId":251458,"journal":{"name":"Frontier materials & technologies","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127802019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.18323/2782-4039-2022-3-1-69-75
L. Zaynullina, E. Sarkeeva, I. Alexandrov, R. Valiev
Goods made of beryllium bronzes got widespread use in the industry due to the complex of properties: high heat conductivity, strength, hardness, wear resistance, and corrosion resistance. They are not magnesium-based and do not spark on impact; therefore, they are essential for the production of non-sparking tools. The alloys of this system are used in the electrical engineering industry; consequently, it is necessary to pay attention to the improvement of the material’s electrical conductivity. The paper studies the microstructure, microhardness, and electrical conductivity of the Cu–2 wt.% Be alloy exposed to high-pressure torsion (HPT). The authors investigated the microstructure and fine structure of the alloy in various states. The study showed that HPT leads to the formation of an ultrafine-grained nanostructured (UFG NS) state with an average size of grains/subgrains of 22±1 mmn. Additional ageing of samples after HPD led to a slight increase in the grains/subgrains size up to 31±1 mmn. In both states, the authors observed nanosized deformation twins. The authors studied the dependences of microhardness and electrical conductivity of the alloy after HPD on the time of further ageing. The study identified that the microhardness increases from 122±3 HV in the initial state up to 525±8 HV after HPD and ageing. The investigation shows that the electrical conductivity substantially better recovers after ageing of the UFG NS state compared to the initial state. The electrical conductivity of the UFG NS state increased from 14.5±0.1 % IACS up to 27.5±0.6 % IACS in conditions similar to the initial state ageing. Therefore, resulting from such processing, the Cu–2 wt.% Be alloy is characterized by its advanced strength properties and electrical conductivity.
{"title":"The influence of aging on microhardness and electrical conductivity of Cu–2 wt. % Be alloy","authors":"L. Zaynullina, E. Sarkeeva, I. Alexandrov, R. Valiev","doi":"10.18323/2782-4039-2022-3-1-69-75","DOIUrl":"https://doi.org/10.18323/2782-4039-2022-3-1-69-75","url":null,"abstract":"Goods made of beryllium bronzes got widespread use in the industry due to the complex of properties: high heat conductivity, strength, hardness, wear resistance, and corrosion resistance. They are not magnesium-based and do not spark on impact; therefore, they are essential for the production of non-sparking tools. The alloys of this system are used in the electrical engineering industry; consequently, it is necessary to pay attention to the improvement of the material’s electrical conductivity. The paper studies the microstructure, microhardness, and electrical conductivity of the Cu–2 wt.% Be alloy exposed to high-pressure torsion (HPT). The authors investigated the microstructure and fine structure of the alloy in various states. The study showed that HPT leads to the formation of an ultrafine-grained nanostructured (UFG NS) state with an average size of grains/subgrains of 22±1 mmn. Additional ageing of samples after HPD led to a slight increase in the grains/subgrains size up to 31±1 mmn. In both states, the authors observed nanosized deformation twins. The authors studied the dependences of microhardness and electrical conductivity of the alloy after HPD on the time of further ageing. The study identified that the microhardness increases from 122±3 HV in the initial state up to 525±8 HV after HPD and ageing. The investigation shows that the electrical conductivity substantially better recovers after ageing of the UFG NS state compared to the initial state. The electrical conductivity of the UFG NS state increased from 14.5±0.1 % IACS up to 27.5±0.6 % IACS in conditions similar to the initial state ageing. Therefore, resulting from such processing, the Cu–2 wt.% Be alloy is characterized by its advanced strength properties and electrical conductivity.","PeriodicalId":251458,"journal":{"name":"Frontier materials & technologies","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133646300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.18323/2782-4039-2022-2-121-132
A. Shchegolkov, A. Shchegolkov, N. Zemtsova
The authors studied the elastomers modified with carbon nanotubes (MWCNTs) with a mass concentration from 1 to 8 % wt. and investigated the modes of heat release of nanomodified elastomers within the range between 30 and 260 V (of alternating current) at different levels of stretching and torsion. Samples of elastomers with the MWCNT concentration from 1 to 5 % wt. in the supply voltage range up to 260 V did not generate heat. The study showed that heat release when feeding composites of elastomers with MWCNTs was observed at a mass concentration of 6 % wt. of MWCNTs and a supply voltage of 70 V. The maximum voltage for an elastomer sample with 6 % wt. of MWCNTs reaches 260 V. An increase in concentration to 7 % wt. causes the increase in the heat release power and the decrease in the maximum supply voltage level to 180 V when the initial heat release voltage is 40 V. At the 8 % wt. concentration, the power increases, and the limiting voltage drops to 100 V, while the initial voltage becomes 36 V. The study identified that when twisting elastomer by 360°, the areas with an increased temperature on the right and in the central zone of the sample (49.5 °C) are formed. The temperature at the bend point increases up to 50.2° С when twisting elastomer by 540°. An increase in the twisting angle to 1080° leads to the formation of areas with the elevated temperature near the right-side current-carrying clamp. It is worth noting the possibility of using the produced samples of elastomers with MWCNTs as sensitive elements of strain sensors, which will allow obtaining the information on physical and chemical parameters according to the principles of measuring the change in electrical resistance that occurs during stretching and torsion.
{"title":"Investigation of heat release in nanomodified elastomers during stretching and torsion under the action of electric voltage","authors":"A. Shchegolkov, A. Shchegolkov, N. Zemtsova","doi":"10.18323/2782-4039-2022-2-121-132","DOIUrl":"https://doi.org/10.18323/2782-4039-2022-2-121-132","url":null,"abstract":"The authors studied the elastomers modified with carbon nanotubes (MWCNTs) with a mass concentration from 1 to 8 % wt. and investigated the modes of heat release of nanomodified elastomers within the range between 30 and 260 V (of alternating current) at different levels of stretching and torsion. Samples of elastomers with the MWCNT concentration from 1 to 5 % wt. in the supply voltage range up to 260 V did not generate heat. The study showed that heat release when feeding composites of elastomers with MWCNTs was observed at a mass concentration of 6 % wt. of MWCNTs and a supply voltage of 70 V. The maximum voltage for an elastomer sample with 6 % wt. of MWCNTs reaches 260 V. An increase in concentration to 7 % wt. causes the increase in the heat release power and the decrease in the maximum supply voltage level to 180 V when the initial heat release voltage is 40 V. At the 8 % wt. concentration, the power increases, and the limiting voltage drops to 100 V, while the initial voltage becomes 36 V. The study identified that when twisting elastomer by 360°, the areas with an increased temperature on the right and in the central zone of the sample (49.5 °C) are formed. The temperature at the bend point increases up to 50.2° С when twisting elastomer by 540°. An increase in the twisting angle to 1080° leads to the formation of areas with the elevated temperature near the right-side current-carrying clamp. It is worth noting the possibility of using the produced samples of elastomers with MWCNTs as sensitive elements of strain sensors, which will allow obtaining the information on physical and chemical parameters according to the principles of measuring the change in electrical resistance that occurs during stretching and torsion.","PeriodicalId":251458,"journal":{"name":"Frontier materials & technologies","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130498297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.18323/2782-4039-2022-1-15-23
A. Vyrodova
A characteristic feature of high-entropy alloys is high strength at maintaining plasticity, wear and corrosion resistance, and fracture toughness at cryogenic temperatures. Currently, CoCrFeNiMn is the best-investigated high-entropy compound. However, its application is limited in the high-temperature region due to the low values of the deforming stress level at the plasticity breaking point at T>296 K. One of the common ways to improve the material durability is the addition of substitution atoms of larger atomic radius, and Al, Ti, and Mo are some of these atoms. The paper presents the analysis of the mechanical behavior of single crystals of CoCrFeNiMn and CoCrFeNiMо FCC high-entropy alloys (at. %) oriented along the [001] direction: the author studied the temperature dependence of critical shear stresses τcr(T) within the temperature range of T=77–973K, the type of dislocation structure, strain hardening coefficient θII, plasticity and fracture at Т=296 K under tension. The study shows that the alloying with Mo atoms 4 at. % of the CoCrFeNi system (at. %) causes the solid solution hardening, and critical shear stresses τcr increase within the entire studied temperature range. The onset of plastic deformation is associated with slip at all temperature tests. At T=296 K, the author identified a planar dislocation structure with flat dislocation pile-ups and dislocation networks in CoCrFeNiMo while in equiatomic CoCrFeNiMn, at such test temperature, a uniform distribution of dislocations was observed in several systems without flat pile-ups. Work hardening coefficient, plasticity, and the level of stresses before fracture turn out to be similar in [001]-crystals of CoCrFeNiMo and CoCrFeNiMn high-entropy alloys, which are determined by the development of slip deformation simultaneously in several systems. Crystals are destroyed viscously at 296 K at the same level of stress.
{"title":"THE INFLUENCE OF CHEMICAL COMPOSITION ON SOLID SOLUTION AND STRAIN HARDENING OF SINGLE CRYSTALS OF FCC HIGH-ENTROPY ALLOYS","authors":"A. Vyrodova","doi":"10.18323/2782-4039-2022-1-15-23","DOIUrl":"https://doi.org/10.18323/2782-4039-2022-1-15-23","url":null,"abstract":"A characteristic feature of high-entropy alloys is high strength at maintaining plasticity, wear and corrosion resistance, and fracture toughness at cryogenic temperatures. Currently, CoCrFeNiMn is the best-investigated high-entropy compound. However, its application is limited in the high-temperature region due to the low values of the deforming stress level at the plasticity breaking point at T>296 K. One of the common ways to improve the material durability is the addition of substitution atoms of larger atomic radius, and Al, Ti, and Mo are some of these atoms. The paper presents the analysis of the mechanical behavior of single crystals of CoCrFeNiMn and CoCrFeNiMо FCC high-entropy alloys (at. %) oriented along the [001] direction: the author studied the temperature dependence of critical shear stresses τcr(T) within the temperature range of T=77–973K, the type of dislocation structure, strain hardening coefficient θII, plasticity and fracture at Т=296 K under tension. The study shows that the alloying with Mo atoms 4 at. % of the CoCrFeNi system (at. %) causes the solid solution hardening, and critical shear stresses τcr increase within the entire studied temperature range. The onset of plastic deformation is associated with slip at all temperature tests. At T=296 K, the author identified a planar dislocation structure with flat dislocation pile-ups and dislocation networks in CoCrFeNiMo while in equiatomic CoCrFeNiMn, at such test temperature, a uniform distribution of dislocations was observed in several systems without flat pile-ups. Work hardening coefficient, plasticity, and the level of stresses before fracture turn out to be similar in [001]-crystals of CoCrFeNiMo and CoCrFeNiMn high-entropy alloys, which are determined by the development of slip deformation simultaneously in several systems. Crystals are destroyed viscously at 296 K at the same level of stress.","PeriodicalId":251458,"journal":{"name":"Frontier materials & technologies","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127753244","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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