Pub Date : 2024-02-08DOI: 10.1134/s1029959924010065
A. V. Bakulin, L. S. Chumakova, S. O. Kasparyan, S. E. Kulkova
Abstract
The combination effect of substitutional impurities of group IVB–VIB transition metals on the oxygen vacancy formation energy in rutile titania was studied by the projector augmented wave method within density functional theory. The pair interaction energy of impurity atoms was estimated depending on the interatomic distance. It was shown that the interaction in the Zr + Zr, Hf + Hf and Nb + Ta pairs leads to the energy preference of their orientation along the <100> direction at a distance of the lattice parameter a. The Mo + Mo and Nb + Mo pairs prefer to orient along the [001] direction at a distance of the lattice parameter c. If the impurity atoms are farther than the third neighbors, then their interaction can be neglected. It was found that the change in the oxygen vacancy formation energy due to doping with several impurities can be estimated as the sum of the energy changes due to single impurity divided by a coefficient whose value depends on the mutual arrangement of the impurity atoms.
摘要 采用密度泛函理论中的投影增强波法研究了 IVB-VIB 族过渡金属取代杂质对金红石型二氧化钛中氧空位形成能的组合效应。根据原子间距离估算了杂质原子的成对相互作用能。结果表明，Zr + Zr、Hf + Hf 和 Nb + Ta 原子对中的相互作用导致它们在晶格参数 a 的距离上沿 <100> 方向取向的能量偏好；Mo + Mo 和 Nb + Mo 原子对在晶格参数 c 的距离上沿 [001] 方向取向的能量偏好。研究发现，掺杂多个杂质引起的氧空位形成能的变化可以用单个杂质引起的能量变化之和除以一个系数来估算，该系数的值取决于杂质原子的相互排列。
{"title":"Combination Effect of Transition Metal Impurities on Oxygen Vacancy Formation Energetics in TiO2","authors":"A. V. Bakulin, L. S. Chumakova, S. O. Kasparyan, S. E. Kulkova","doi":"10.1134/s1029959924010065","DOIUrl":"https://doi.org/10.1134/s1029959924010065","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The combination effect of substitutional impurities of group IVB–VIB transition metals on the oxygen vacancy formation energy in rutile titania was studied by the projector augmented wave method within density functional theory. The pair interaction energy of impurity atoms was estimated depending on the interatomic distance. It was shown that the interaction in the Zr + Zr, Hf + Hf and Nb + Ta pairs leads to the energy preference of their orientation along the <100> direction at a distance of the lattice parameter <i>a</i>. The Mo + Mo and Nb + Mo pairs prefer to orient along the [001] direction at a distance of the lattice parameter <i>c</i>. If the impurity atoms are farther than the third neighbors, then their interaction can be neglected. It was found that the change in the oxygen vacancy formation energy due to doping with several impurities can be estimated as the sum of the energy changes due to single impurity divided by a coefficient whose value depends on the mutual arrangement of the impurity atoms.</p>","PeriodicalId":726,"journal":{"name":"Physical Mesomechanics","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139768786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-08DOI: 10.1134/s102995992401003x
V. M. Farber, O. V. Selivanova, A. N. Morozova, V. A. Khotinov, M. S. Khadyev, A. Yu. Zhilyakov
Abstract
The paper reports on a transmission electron microscopy analysis of the dislocation structure of normalized 09G2S steel with strain aging. The analysis shows that in a steel specimen deformed to its yield stress, the dislocation density peaks at the center of a strain localization band (in its active zone) and decreases by about an order of magnitude at its sides. The structure of these band zones, which are in different strain hardening stages, is examined and the Burgers vector of dislocations of the primary slip system is determined. The ends of such dislocations form ordered planar dipole walls, leading to polygonization by dislocation slip. Also considered is the specimen structure at the yield and ultimate stresses.
{"title":"Dislocation Structure in a Strain Localization Band Formed in Normalized 09G2S Steel under Tension","authors":"V. M. Farber, O. V. Selivanova, A. N. Morozova, V. A. Khotinov, M. S. Khadyev, A. Yu. Zhilyakov","doi":"10.1134/s102995992401003x","DOIUrl":"https://doi.org/10.1134/s102995992401003x","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The paper reports on a transmission electron microscopy analysis of the dislocation structure of normalized 09G2S steel with strain aging. The analysis shows that in a steel specimen deformed to its yield stress, the dislocation density peaks at the center of a strain localization band (in its active zone) and decreases by about an order of magnitude at its sides. The structure of these band zones, which are in different strain hardening stages, is examined and the Burgers vector of dislocations of the primary slip system is determined. The ends of such dislocations form ordered planar dipole walls, leading to polygonization by dislocation slip. Also considered is the specimen structure at the yield and ultimate stresses.</p>","PeriodicalId":726,"journal":{"name":"Physical Mesomechanics","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139768788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-08DOI: 10.1134/s1029959924010016
V. M. Fomin, A. G. Malikov, A. A. Golyshev, N. V. Bulina, M. A. Gulov, I. E. Vitoshkin, T. A. Brusentseva, A. A. Filippov, A. V. Mishin
Abstract
The paper presents experimental studies on laser cladding synthesis of a titanium matrix composite based on Ti64 titanium alloy and TiB2 ceramic reinforcement. The weight percentage of TiB2 ceramics in the composite was 5, 10 and 15%. The phase composition of the resulting materials was analyzed by standard X-ray diffraction and synchrotron X-ray diffraction. It was found that the structure of the titanium matrix composite with 5 wt % ceramics consists of TiB nanowhiskers, and that of samples with higher ceramic content exhibits TiB whiskers with a width of several micrometers. The addition of TiB2 ceramics increases Young’s modulus, nano- and microhardness of composite samples compared to Ti64 alloy. The indentation method was used to study the formation of a phase that is different from TiB2 ceramics and TiB microwhiskers and has elastic properties exceeding the elastic properties of the original Ti64 matrix phase. Analytical predictions showed an increase in the effective elastic properties of the formed heterogeneous material with the predicted new phase. It was also found that a lower friction coefficient can be achieved by forming a structure with nanowhiskers, while higher Young’s modulus and microhardness can be obtained by forming a structure with microwhiskers.
{"title":"Structural-Phase State and Mechanical Properties of a Laser Cladding Titanium Matrix Composite Based on Ti64 Alloy and TiB2 Ceramics","authors":"V. M. Fomin, A. G. Malikov, A. A. Golyshev, N. V. Bulina, M. A. Gulov, I. E. Vitoshkin, T. A. Brusentseva, A. A. Filippov, A. V. Mishin","doi":"10.1134/s1029959924010016","DOIUrl":"https://doi.org/10.1134/s1029959924010016","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The paper presents experimental studies on laser cladding synthesis of a titanium matrix composite based on Ti64 titanium alloy and TiB<sub>2</sub> ceramic reinforcement. The weight percentage of TiB<sub>2</sub> ceramics in the composite was 5, 10 and 15%. The phase composition of the resulting materials was analyzed by standard X-ray diffraction and synchrotron X-ray diffraction. It was found that the structure of the titanium matrix composite with 5 wt % ceramics consists of TiB nanowhiskers, and that of samples with higher ceramic content exhibits TiB whiskers with a width of several micrometers. The addition of TiB<sub>2</sub> ceramics increases Young’s modulus, nano- and microhardness of composite samples compared to Ti64 alloy. The indentation method was used to study the formation of a phase that is different from TiB<sub>2</sub> ceramics and TiB microwhiskers and has elastic properties exceeding the elastic properties of the original Ti64 matrix phase. Analytical predictions showed an increase in the effective elastic properties of the formed heterogeneous material with the predicted new phase. It was also found that a lower friction coefficient can be achieved by forming a structure with nanowhiskers, while higher Young’s modulus and microhardness can be obtained by forming a structure with microwhiskers.</p>","PeriodicalId":726,"journal":{"name":"Physical Mesomechanics","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139768789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-08DOI: 10.1134/s1029959924010028
E. S. Emelianova, O. S. Zinovieva, V. A. Romanova, R. R. Balokhonov, M. Pisarev
Abstract
The paper provides a review of experimental and numerical studies of deformation-induced surface roughening in loaded metals and alloys. Consideration is given to various parameters for assessing strain-induced surface roughness, factors influencing the roughness characteristics, and models describing surface roughening in polycrystalline alloys.
{"title":"Experimental and Numerical Investigation of Mesoscale Deformation-Induced Surface Roughening in Polycrystalline Metals and Alloys (Review)","authors":"E. S. Emelianova, O. S. Zinovieva, V. A. Romanova, R. R. Balokhonov, M. Pisarev","doi":"10.1134/s1029959924010028","DOIUrl":"https://doi.org/10.1134/s1029959924010028","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The paper provides a review of experimental and numerical studies of deformation-induced surface roughening in loaded metals and alloys. Consideration is given to various parameters for assessing strain-induced surface roughness, factors influencing the roughness characteristics, and models describing surface roughening in polycrystalline alloys.</p>","PeriodicalId":726,"journal":{"name":"Physical Mesomechanics","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139768575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-08DOI: 10.1134/s1029959924010090
A. Fedoseeva
Abstract
The creep resistance and structure of 10% Cr–3% Сo–2% W–0.29% Cu–0.17% Re steel with 0.1% carbon, low nitrogen content and high boron content were investigated by creep rupture testing at a temperature of 650°C and stresses from 200 to 100 MPa applied in 20-MPa increments. For comparison, 9% Cr steel with 0.1% carbon, 0.05% nitrogen, and 0.005% boron was considered. The steels were subjected to preliminary heat treatment including normalizing at 1050°C for 1 hour, tempering at 750–770°C for 3 hours, and cooling in air. The structures of both heat-treated steels exhibited martensite laths with boundaries pinned by М23С6 carbides, and the rearrangement of dislocations was retarded by MX particles. A significant difference between 10% Cr and 9% Cr steels was the presence of fine М23С6 carbide particles characterized by orientational relationships with the ferrite matrix and MX carbonitrides, whose volume fraction was 6 times lower. Short-term tensile tests at room temperature showed no differences between the steels, while the creep rupture strength of 10% Cr steel was 13% higher than for 9% Cr steel. The creep deformation mechanism of the steels was also different. Structural analysis of 10% Cr steel after creep tests revealed no substantial changes in its lath structure: the lath width increased by only 58% and the dislocation density was reduced by a factor of 2. Comparison with 9% Cr steel showed that the good structural stability of 10% Cr steel during creep is caused by the high coarsening resistance of second phase particles, whose coarsening rate is 1-2 orders of magnitude lower than that in 9% Cr steel.
{"title":"Creep Resistance and Structure of 10% Cr–3% Сo–2% W–0.29% Cu–0.17% Re Steel with Low Nitrogen and High Boron Contents for Unit Components of Coal Power Plants","authors":"A. Fedoseeva","doi":"10.1134/s1029959924010090","DOIUrl":"https://doi.org/10.1134/s1029959924010090","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The creep resistance and structure of 10% Cr–3% Сo–2% W–0.29% Cu–0.17% Re steel with 0.1% carbon, low nitrogen content and high boron content were investigated by creep rupture testing at a temperature of 650°C and stresses from 200 to 100 MPa applied in 20-MPa increments. For comparison, 9% Cr steel with 0.1% carbon, 0.05% nitrogen, and 0.005% boron was considered. The steels were subjected to preliminary heat treatment including normalizing at 1050°C for 1 hour, tempering at 750–770°C for 3 hours, and cooling in air. The structures of both heat-treated steels exhibited martensite laths with boundaries pinned by М<sub>23</sub>С<sub>6</sub> carbides, and the rearrangement of dislocations was retarded by MX particles. A significant difference between 10% Cr and 9% Cr steels was the presence of fine М<sub>23</sub>С<sub>6</sub> carbide particles characterized by orientational relationships with the ferrite matrix and MX carbonitrides, whose volume fraction was 6 times lower. Short-term tensile tests at room temperature showed no differences between the steels, while the creep rupture strength of 10% Cr steel was 13% higher than for 9% Cr steel. The creep deformation mechanism of the steels was also different. Structural analysis of 10% Cr steel after creep tests revealed no substantial changes in its lath structure: the lath width increased by only 58% and the dislocation density was reduced by a factor of 2. Comparison with 9% Cr steel showed that the good structural stability of 10% Cr steel during creep is caused by the high coarsening resistance of second phase particles, whose coarsening rate is 1-2 orders of magnitude lower than that in 9% Cr steel.</p>","PeriodicalId":726,"journal":{"name":"Physical Mesomechanics","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139768790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-08DOI: 10.1134/s1029959924010077
N. M. Rusin, A. L. Skorentsev, K. O. Akimov
Abstract
The paper analyzes the features of plastic flow in compression in sintered Al–Sn–Fe alloys, some of which were exposed to compaction in a closed die at a pressure of 300 MPa and temperature of 250°C, and some to equal-channel angular pressing by route A (ECAP-A) at the same temperature. The analysis shows that the sintered composites comprise agglomerates of Sn-cemented Al3Fe particles formed in place of Fe powder particles due to the interaction of Al and Fe in sintering. The agglomerates are strong but sufficiently ductile, due to Sn, to survive under deformation and to efficiently impede the propagation of strain localization bands and microcracks. In compression, such agglomerates in Al–20Sn–17Al3Fe hold their form, moving as solid units, while the composite displays good ductility. In ECAP-A, they extend in the direction of plastic flow, and this adversely affects their ductility in further compression.
{"title":"Mechanical Properties of Sintered Al–Sn–Fe Alloys","authors":"N. M. Rusin, A. L. Skorentsev, K. O. Akimov","doi":"10.1134/s1029959924010077","DOIUrl":"https://doi.org/10.1134/s1029959924010077","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The paper analyzes the features of plastic flow in compression in sintered Al–Sn–Fe alloys, some of which were exposed to compaction in a closed die at a pressure of 300 MPa and temperature of 250°C, and some to equal-channel angular pressing by route A (ECAP-A) at the same temperature. The analysis shows that the sintered composites comprise agglomerates of Sn-cemented Al<sub>3</sub>Fe particles formed in place of Fe powder particles due to the interaction of Al and Fe in sintering. The agglomerates are strong but sufficiently ductile, due to Sn, to survive under deformation and to efficiently impede the propagation of strain localization bands and microcracks. In compression, such agglomerates in Al<i>–</i>20Sn<i>–</i>17Al<sub>3</sub>Fe hold their form, moving as solid units, while the composite displays good ductility. In ECAP-A, they extend in the direction of plastic flow, and this adversely affects their ductility in further compression.</p>","PeriodicalId":726,"journal":{"name":"Physical Mesomechanics","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139768574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-08DOI: 10.1134/s1029959924010089
A. E. Chesnokov, V. O. Drozdov, K. A. Skorokhod, A. V. Smirnov, A. N. Cherepanov
Abstract
This study examines how preliminary mechanical milling of a modifying TiN-based powder mixture affects the morphology of the CO2 laser-treated surface, the weld pool morphology, and the cross-sectional structure of the material. Ultrafine titanium nitride particles used as nanomodifier have low wettability by liquid metal, are not entrained by its convective flows, and tend to accumulate in the subsurface layer, which makes it difficult to effectively modify the structure within the treated material. Ball milling of the modifying Ti + TiN mixture for 9 min leads to the formation of composite particles (5–7 µm) with ultrafine TiN particles uniformly distributed over their surface and volume. When the composite particles are melted by the laser beam, they turn to ultrafine TiN particles of nanomodifier coated with a thin titanium layer, which have a smaller contact angle. As a result, the particles are more evenly distributed over the weld pool and the number of crystallization centers increases, leading to the formation of a fine homogeneous structure of the material. The microhardness increases by 32%, and its standard deviation decreases by a factor of 1.5–3.0.
摘要 本研究探讨了改性 TiN 基粉末混合物的初步机械研磨如何影响 CO2 激光处理表面的形态、焊接熔池形态以及材料的横截面结构。用作纳米改性剂的超细氮化钛颗粒对液态金属的润湿性较低，不会被液态金属的对流夹带，容易在次表层堆积，因此很难有效地改变处理材料内部的结构。将改性 Ti + TiN 混合物球磨 9 分钟，可形成复合颗粒（5-7 微米），其表面和体积上均匀分布着超细 TiN 颗粒。当复合颗粒被激光束熔化时，它们会变成纳米改性剂的超细 TiN 颗粒，表面涂有一层薄薄的钛层，接触角较小。因此，颗粒在焊接熔池中的分布更加均匀，结晶中心的数量增加，从而形成了材料的精细均匀结构。显微硬度增加了 32%，其标准偏差降低了 1.5-3.0 倍。
{"title":"Effect of Preliminary Ball Milling of Nanomodifiers on Their Efficiency in Laser Surface Treatment of Titanium","authors":"A. E. Chesnokov, V. O. Drozdov, K. A. Skorokhod, A. V. Smirnov, A. N. Cherepanov","doi":"10.1134/s1029959924010089","DOIUrl":"https://doi.org/10.1134/s1029959924010089","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>This study examines how preliminary mechanical milling of a modifying TiN-based powder mixture affects the morphology of the CO<sub>2</sub> laser-treated surface, the weld pool morphology, and the cross-sectional structure of the material. Ultrafine titanium nitride particles used as nanomodifier have low wettability by liquid metal, are not entrained by its convective flows, and tend to accumulate in the subsurface layer, which makes it difficult to effectively modify the structure within the treated material. Ball milling of the modifying Ti + TiN mixture for 9 min leads to the formation of composite particles (5–7 µm) with ultrafine TiN particles uniformly distributed over their surface and volume. When the composite particles are melted by the laser beam, they turn to ultrafine TiN particles of nanomodifier coated with a thin titanium layer, which have a smaller contact angle. As a result, the particles are more evenly distributed over the weld pool and the number of crystallization centers increases, leading to the formation of a fine homogeneous structure of the material. The microhardness increases by 32%, and its standard deviation decreases by a factor of 1.5–3.0.</p>","PeriodicalId":726,"journal":{"name":"Physical Mesomechanics","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139768792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-01DOI: 10.1134/s1029959924010107
Abstract
Impact tests of low-alloy martensitic-bainitic steel AB2 showed that the scale of dynamic deformation and the fracture mechanism change in a threshold manner. The change in the mechanism and scale of fracture is triggered by the resonant excitation of large-scale structural elements of the material (grain conglomerates) due to plastic flow oscillations. In this case, the grain-boundary mechanism of dynamic fracture is replaced by a transcrystalline one. Beyond the strain rate threshold, mesoscopic elementary carriers of dynamic deformation are divided into two groups: low-velocity and high-velocity. Accordingly, the velocity distribution of mesoparticles shows two humps. The velocity spread of mesoparticles sharply increases under these conditions, while the mass velocity defect (change in the shock wave amplitude) becomes negative. The latter fact indicates the local acceleration of mesoparticles in discrete regions of the target (the so-called shooting of mesoparticles in the shock wave direction). Transcrystalline cracks are randomly distributed throughout the specimen and have a random orientation.
{"title":"Meso–Macro Energy Exchange in Shock-Wave Processes and Dynamic Strength of AB2 Steel","authors":"","doi":"10.1134/s1029959924010107","DOIUrl":"https://doi.org/10.1134/s1029959924010107","url":null,"abstract":"<span> <h3>Abstract</h3> <p>Impact tests of low-alloy martensitic-bainitic steel AB2 showed that the scale of dynamic deformation and the fracture mechanism change in a threshold manner. The change in the mechanism and scale of fracture is triggered by the resonant excitation of large-scale structural elements of the material (grain conglomerates) due to plastic flow oscillations. In this case, the grain-boundary mechanism of dynamic fracture is replaced by a transcrystalline one. Beyond the strain rate threshold, mesoscopic elementary carriers of dynamic deformation are divided into two groups: low-velocity and high-velocity. Accordingly, the velocity distribution of mesoparticles shows two humps. The velocity spread of mesoparticles sharply increases under these conditions, while the mass velocity defect (change in the shock wave amplitude) becomes negative. The latter fact indicates the local acceleration of mesoparticles in discrete regions of the target (the so-called shooting of mesoparticles in the shock wave direction). Transcrystalline cracks are randomly distributed throughout the specimen and have a random orientation.</p> </span>","PeriodicalId":726,"journal":{"name":"Physical Mesomechanics","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139768572","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-01DOI: 10.1134/s1029959924010041
Abstract
This paper presents an experimental study of energy dissipation caused by fatigue crack growth in Grade 2 titanium and titanium alloys Ti-1.1Al-0.9Mn and Ti-4.6Al-1.77V using the original heat flux method. It is shown that significant structural changes occur in the material under plastic deformation, leading to internal energy evolution. As is known, a large part of the deformation energy is dissipated as heat. The developed method allows high-accuracy measurements of the heat flux caused by plastic zone development at the crack tip directly in the fatigue experiment. Simultaneous measurements of the crack length and displacements in the stress concentration zone allow estimating the energy balance of the tested specimens. Analysis of the obtained data confirms that the stored strain energy reflecting the structural state of the material can be used as a fracture criterion. Based on the heat flux data, a kinetic equation is derived for predicting the rate of fatigue crack growth under Paris’s law by the energy dissipation rate.
{"title":"Development of an Energy-Based Experimental Method for Estimation of Fatigue Crack Evolution in Titanium Alloys","authors":"","doi":"10.1134/s1029959924010041","DOIUrl":"https://doi.org/10.1134/s1029959924010041","url":null,"abstract":"<span> <h3>Abstract</h3> <p>This paper presents an experimental study of energy dissipation caused by fatigue crack growth in Grade 2 titanium and titanium alloys Ti-1.1Al-0.9Mn and Ti-4.6Al-1.77V using the original heat flux method. It is shown that significant structural changes occur in the material under plastic deformation, leading to internal energy evolution. As is known, a large part of the deformation energy is dissipated as heat. The developed method allows high-accuracy measurements of the heat flux caused by plastic zone development at the crack tip directly in the fatigue experiment. Simultaneous measurements of the crack length and displacements in the stress concentration zone allow estimating the energy balance of the tested specimens. Analysis of the obtained data confirms that the stored strain energy reflecting the structural state of the material can be used as a fracture criterion. Based on the heat flux data, a kinetic equation is derived for predicting the rate of fatigue crack growth under Paris’s law by the energy dissipation rate.</p> </span>","PeriodicalId":726,"journal":{"name":"Physical Mesomechanics","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139768571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-15DOI: 10.1134/s1029959923060024
A. E. Filippov, V. L. Popov
Abstract
The paper analyzes a numerical model of an “active medium” with linear elasticity and a negative initial dissipation constant dynamically renormalized under deformation. The analysis shows that such a system, being seemingly unstable over a wide range of geometries and origins of deformation, can spontaneously reach stable dynamic modes in which its time- and space-alternating dissipation forms complex quasiperiodic patterns and its total volume (length, area) oscillates on a large scale. The results presented in the paper are of interest in academic terms and in terms of mechanical and biological application.
{"title":"Spontaneous Stabilization and Large-Scale Oscillations of an Active Medium with Negative Dissipation","authors":"A. E. Filippov, V. L. Popov","doi":"10.1134/s1029959923060024","DOIUrl":"https://doi.org/10.1134/s1029959923060024","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The paper analyzes a numerical model of an “active medium” with linear elasticity and a negative initial dissipation constant dynamically renormalized under deformation. The analysis shows that such a system, being seemingly unstable over a wide range of geometries and origins of deformation, can spontaneously reach stable dynamic modes in which its time- and space-alternating dissipation forms complex quasiperiodic patterns and its total volume (length, area) oscillates on a large scale. The results presented in the paper are of interest in academic terms and in terms of mechanical and biological application.</p>","PeriodicalId":726,"journal":{"name":"Physical Mesomechanics","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138688913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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