{"title":"Ti3Ni4 precipitation in heat-treated nanocrytalline Ti – 50.9 at. % Ni alloy","authors":"S. Girsova, T. Poletika","doi":"10.1063/1.5131979","DOIUrl":"https://doi.org/10.1063/1.5131979","url":null,"abstract":"The structure of a nanocrystalline Ti–50.9 at. % Ni alloy with mixed subgrain/nanograin structure is investigated by transmission electron microscopy after annealing at temperature 400°C. The size, morphology and distribution of Ti3Ni4 particles formed in the process of the decomposition of a TiNi B2 solid solution are investigated. It is shown that the Ti3Ni4 particles precipitate in the substructure in the low-angle boundaries regions. The precipitation of coherent particles in subgrains is possible with the latter sizes less than 100 nm. At the same time, precipitations of Ti3Ni4 particles are not observed inside the nanograins.The structure of a nanocrystalline Ti–50.9 at. % Ni alloy with mixed subgrain/nanograin structure is investigated by transmission electron microscopy after annealing at temperature 400°C. The size, morphology and distribution of Ti3Ni4 particles formed in the process of the decomposition of a TiNi B2 solid solution are investigated. It is shown that the Ti3Ni4 particles precipitate in the substructure in the low-angle boundaries regions. The precipitation of coherent particles in subgrains is possible with the latter sizes less than 100 nm. At the same time, precipitations of Ti3Ni4 particles are not observed inside the nanograins.","PeriodicalId":20637,"journal":{"name":"PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS WITH HIERARCHICAL STRUCTURE FOR NEW TECHNOLOGIES AND RELIABLE STRUCTURES 2019","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77715855","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}
N. Soboleva, A. Makarov, P. Skorynina, E. Nikolaeva, I. Malygina
{"title":"The effect of load during frictional treatment with a DBN indenter on the surface finish of the NiCrBSi–Cr3C2 laser clad coating","authors":"N. Soboleva, A. Makarov, P. Skorynina, E. Nikolaeva, I. Malygina","doi":"10.1063/1.5132212","DOIUrl":"https://doi.org/10.1063/1.5132212","url":null,"abstract":"The authors consider the hardness and surface finish of the composite NiCrBSi–Cr3C2 laser clad coating after frictional treatment with a dense cubic boron nitride (DBN) indenter in air at loads on the indenter of 350, 500 and 700 N in comparison with the surface characteristics after grinding. Frictional treatment in all cases leads to surface hardening. Frictional treatment at loads of 350–500 N ensures the formation of surfaces with the lowest roughness parameters and contributes to the preservation on the surface of large hard chromium carbides, while frictional treatment at a load of 700 N causes the destruction of Cr3C2 carbides on the surface of the coating.The authors consider the hardness and surface finish of the composite NiCrBSi–Cr3C2 laser clad coating after frictional treatment with a dense cubic boron nitride (DBN) indenter in air at loads on the indenter of 350, 500 and 700 N in comparison with the surface characteristics after grinding. Frictional treatment in all cases leads to surface hardening. Frictional treatment at loads of 350–500 N ensures the formation of surfaces with the lowest roughness parameters and contributes to the preservation on the surface of large hard chromium carbides, while frictional treatment at a load of 700 N causes the destruction of Cr3C2 carbides on the surface of the coating.","PeriodicalId":20637,"journal":{"name":"PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS WITH HIERARCHICAL STRUCTURE FOR NEW TECHNOLOGIES AND RELIABLE STRUCTURES 2019","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79288349","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}
N. Grishaeva, S. Bochkareva, S. Panin, Le Thi My Hiep, B. Lyukshin, I. Panov, Nguen Duc Ahn
{"title":"Content optimization of polyphenylene sulfide composites filled with carbon fibers of different size","authors":"N. Grishaeva, S. Bochkareva, S. Panin, Le Thi My Hiep, B. Lyukshin, I. Panov, Nguen Duc Ahn","doi":"10.1063/1.5131988","DOIUrl":"https://doi.org/10.1063/1.5131988","url":null,"abstract":"The chemical content of polyphenylene sulfide (PPS) based composite with specified physical–mechanical properties is determined in the study with the use of experimental data on the dependence of effective properties (volumetric wear, elastic modulus, elongation at break, etc.) versus the values of control parameters. The latter are degree of filling with (i) Short Carbon Fibers (SCF) of ∼70 µm long and (ii) Chopped Carbon Fibers (CCF) ∼2 mm long. After the required number of experimental reference points has been determined the technique for data supplementation up to a regular numerical array with the use of linear interpolation is employed. The obtained dependences of the effective properties versus the control parameter values are constructed in the form of surfaces and corresponding isolines. At the contour plots, a region with the required effective properties is then highlighted. Since the regions overlap each other, their intersection determines the allowable control parameters range that impart the required values to the effective properties. The possibility to design filled polymer materials with a complex of predefined strain-strength and tribological properties is demonstrated. The experimental results are used to gain the reference points in contrast to the previously used approach when a set of computational experiment data were employed. On the one hand, the combination of a full-scale laboratory and computational experiments makes the process of modeling and design materials more evident, clear and reasonable from a physical point of view. On the other hand, it allows to interpret the results as more reliable, as well as less time and material consuming.The chemical content of polyphenylene sulfide (PPS) based composite with specified physical–mechanical properties is determined in the study with the use of experimental data on the dependence of effective properties (volumetric wear, elastic modulus, elongation at break, etc.) versus the values of control parameters. The latter are degree of filling with (i) Short Carbon Fibers (SCF) of ∼70 µm long and (ii) Chopped Carbon Fibers (CCF) ∼2 mm long. After the required number of experimental reference points has been determined the technique for data supplementation up to a regular numerical array with the use of linear interpolation is employed. The obtained dependences of the effective properties versus the control parameter values are constructed in the form of surfaces and corresponding isolines. At the contour plots, a region with the required effective properties is then highlighted. Since the regions overlap each other, their intersection determines the allowable control parameters range that impart t...","PeriodicalId":20637,"journal":{"name":"PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS WITH HIERARCHICAL STRUCTURE FOR NEW TECHNOLOGIES AND RELIABLE STRUCTURES 2019","volume":"42 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79969234","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}
{"title":"Particularities of ensuring the precision of filaments from 12H18N9T steel for additive manufacturing at their fabrication","authors":"V. Yanpolskiy, A. Tyurin, A. Ruktuev","doi":"10.1063/1.5132259","DOIUrl":"https://doi.org/10.1063/1.5132259","url":null,"abstract":"The issues of ensuring the accuracy of the filaments’ production for additive manufacturing using the electron beam energy at the stage of drawing of a workpiece made of 12H18N9T steel were considered. The reduction ratio varied in the range from e = 5 % to e = 67.5 %. Calculations showed that the dimensions of a workpiece for producing filaments with a diameter of O 1.3-0.09 mm was limited by O 4.27-0.17 mm. It was experimentally established that the diameter of a filament made of 12H18N9T steel after the last reducing step (1.3 mm) exceeded the allowable diameter (1.3−0,09 mm) and equaled to 1.37 mm. This deviation is probably induced by elasto-plastic strains occurring in the wire in the drawing process. To provide the required accuracy of the filaments with a diameter of O 1.3-0.09 obtained by drawing of 12H18N9T steel, it was recommended to grin the diameter of a die taking into account the magnitude of the elastic deformations, i.e. provide the diameter 0.05 mm smaller than required.","PeriodicalId":20637,"journal":{"name":"PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS WITH HIERARCHICAL STRUCTURE FOR NEW TECHNOLOGIES AND RELIABLE STRUCTURES 2019","volume":"42 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81355398","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}
{"title":"Physical mesomechanics based interdisciplinary approach to the development of new methods for managing deformation process in fault zones","authors":"V. Ruzhich, S. Psakhie, E. Shilko, E. Levina","doi":"10.1063/1.5132167","DOIUrl":"https://doi.org/10.1063/1.5132167","url":null,"abstract":"In the paper, we discuss an approach to the development of methods for managing seismotectonic deformation processes in a multiscale block-structured Earth’s Crust from the viewpoint of the concept of physical mesomechanics. To date, there are no convincing results of many year researches in the fields of earthquake prediction and prevention of the dangerous man-caused and tectonic earthquakes. Therefore, in recent decades, there has been an increasingly active search for new ways to solve the problem of seismic safety. The aim of our research team’s activity is to provide a scientific rationale for a multidisciplinary approach to reduce the excess level of shear stresses in the fault zones to a safe background level by “spending” it on mechanical destruction and thermal processes in rocks during aseismic and co-seismic slip. The authors summarize the main results of modeling of geological and geophysical processes in the field of preparation of different scale seismogenic events, as well as the results of complex man-made impacts on segments of seismically active faults. The data obtained on segments of different scale faults within the Baikal rift zone and Mongolia confirm the possibility of implementing such an approach. For the practical implementation of such a project at highly stressed fault zones, it is necessary to carry out vertical, oblique and horizontal multilateral drilling with an injection of fluids of different compositions in combination with vibro-pulse stimulations to achieve safe relaxation of shear stresses.","PeriodicalId":20637,"journal":{"name":"PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS WITH HIERARCHICAL STRUCTURE FOR NEW TECHNOLOGIES AND RELIABLE STRUCTURES 2019","volume":"77 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82295355","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}
{"title":"The evolution of the structure and properties of the composite electron-beam coatings of Ti-B-Fe system, modified by ZrO2 ultrafine powder","authors":"K. Kolesnikova, N. Gal’chenko","doi":"10.1063/1.5132032","DOIUrl":"https://doi.org/10.1063/1.5132032","url":null,"abstract":"The objective of the current study was to investigate the effect of ZrO2 ultrafine powder on the structure and properties of the composite coatings obtained from a mixture of thermo-reactive powders of the Ti-B-Fe system. The results of the metallographic and structural x-ray analysis, as well as tribological and hardness analyses showed that the introduction of zirconium dioxide alters the phase composition, reduces the hardness by a factor of 2-4, reduces the grain size, and increases the wear resistance of the coating formed in the process of electron-beam welding.The objective of the current study was to investigate the effect of ZrO2 ultrafine powder on the structure and properties of the composite coatings obtained from a mixture of thermo-reactive powders of the Ti-B-Fe system. The results of the metallographic and structural x-ray analysis, as well as tribological and hardness analyses showed that the introduction of zirconium dioxide alters the phase composition, reduces the hardness by a factor of 2-4, reduces the grain size, and increases the wear resistance of the coating formed in the process of electron-beam welding.","PeriodicalId":20637,"journal":{"name":"PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS WITH HIERARCHICAL STRUCTURE FOR NEW TECHNOLOGIES AND RELIABLE STRUCTURES 2019","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82541263","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}
{"title":"Features of plastic deformations of quartz-pyrite mineral associations of the Gabriel mine","authors":"D. Lychagin, A. Bibko, L. Zyryanova","doi":"10.1063/1.5132069","DOIUrl":"https://doi.org/10.1063/1.5132069","url":null,"abstract":"Rocks of the Gabriel mine (East Kazakhstan) belong to intensively modified milonites. These rocks in the Ore Altai are often ore-bearing for metals such as zinc, lead, copper and gold. Milonites are formed by imposing deformations on the original rocks. These rocks are interesting for large studies. Using the EBSD method allows us to investigate the deformation stage of mineral formation more detailed. In this work, we studied sections of quartz porphyroblasts with different volume fractions of pyrite. As a result, we determined the influence of the pyrite volume fraction on the degree of quartz deformation and the possible presence of water in the later stages of mineral.Rocks of the Gabriel mine (East Kazakhstan) belong to intensively modified milonites. These rocks in the Ore Altai are often ore-bearing for metals such as zinc, lead, copper and gold. Milonites are formed by imposing deformations on the original rocks. These rocks are interesting for large studies. Using the EBSD method allows us to investigate the deformation stage of mineral formation more detailed. In this work, we studied sections of quartz porphyroblasts with different volume fractions of pyrite. As a result, we determined the influence of the pyrite volume fraction on the degree of quartz deformation and the possible presence of water in the later stages of mineral.","PeriodicalId":20637,"journal":{"name":"PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS WITH HIERARCHICAL STRUCTURE FOR NEW TECHNOLOGIES AND RELIABLE STRUCTURES 2019","volume":"18 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85493252","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}
{"title":"X-ray diffraction method for quantitative estimation of elastic modulus in materials with gradient structure","authors":"M. Ostapenko, L. Meisner","doi":"10.1063/1.5132124","DOIUrl":"https://doi.org/10.1063/1.5132124","url":null,"abstract":"The efficiency of X-ray diffraction (XRD) method for quantitative estimation of elastic modulus in materials with gradient structure have been demonstrated in the paper. This method was used to calculate the elastic modulus for NiTi samples irradiated at a beam energy E= 15 J/cm2 and pulse duration τ = 150 µsx. It is determined that the compared values of XRD elastic modulus E(hkl, ψ) and elastic modulus En obtained for the same samples by nanoindentation are close.The efficiency of X-ray diffraction (XRD) method for quantitative estimation of elastic modulus in materials with gradient structure have been demonstrated in the paper. This method was used to calculate the elastic modulus for NiTi samples irradiated at a beam energy E= 15 J/cm2 and pulse duration τ = 150 µsx. It is determined that the compared values of XRD elastic modulus E(hkl, ψ) and elastic modulus En obtained for the same samples by nanoindentation are close.","PeriodicalId":20637,"journal":{"name":"PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS WITH HIERARCHICAL STRUCTURE FOR NEW TECHNOLOGIES AND RELIABLE STRUCTURES 2019","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88974857","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}
{"title":"Effect of heat treatment on structure and mechanical properties of 12Cr-3Co steel with low N and high B contents","authors":"I. Nikitin, A. Fedoseeva, N. Dudova, R. Kaibyshev","doi":"10.1063/1.5132109","DOIUrl":"https://doi.org/10.1063/1.5132109","url":null,"abstract":"The effect of heat treatment on the microstructure and mechanical properties of Febal-0.1 wt.%C-12Cr-3Co-2.5W-1Cu-VNbTaBN steel was investigated. After normalization in the range of 1050-1150°C, the martensitic structure was dominant; δ-ferrite content was about 10%. When the temperature of normalizing increased from 1050°C to 1150°C, the average size of prior austenite grains increased from 44 to 68 µm. After tempering at 750, 770 and 800°C, tempered martensitic lath structure with a high dislocation density within martensitic laths contained nanosized M23C6 carbides along the boundaries of prior austenite grains and laths and (Ta,Nb)X carbonitrides randomly distributed in the ferritic matrix. The average sizes of M23C6 carbides and (Ta,Nb)X carbonitrides were about 50 nm and 40 nm, respectively, regardless of tempering temperature. The M6C carbide particles were also observed along the boundaries of prior austenite grains and pockets as well as along the boundaries between δ-ferrite and martensite; their amount was negligible. When tempering temperature increased from 750 to 800°C, the particle density on the boundaries between δ- ferrite/martensite decreased from 3.8 to 0.2 µm-1. A relationship between the lath size (h) and the density of free dislocations (ρ) can be described as h = (5.41/√ρ) - 0.07. Increasing the tempering temperature to 800°C led to a decrease in the hardness up to ∼220 HB, yield stress and ultimate tensile stress up to 520 and 700 MPa, respectively.The effect of heat treatment on the microstructure and mechanical properties of Febal-0.1 wt.%C-12Cr-3Co-2.5W-1Cu-VNbTaBN steel was investigated. After normalization in the range of 1050-1150°C, the martensitic structure was dominant; δ-ferrite content was about 10%. When the temperature of normalizing increased from 1050°C to 1150°C, the average size of prior austenite grains increased from 44 to 68 µm. After tempering at 750, 770 and 800°C, tempered martensitic lath structure with a high dislocation density within martensitic laths contained nanosized M23C6 carbides along the boundaries of prior austenite grains and laths and (Ta,Nb)X carbonitrides randomly distributed in the ferritic matrix. The average sizes of M23C6 carbides and (Ta,Nb)X carbonitrides were about 50 nm and 40 nm, respectively, regardless of tempering temperature. The M6C carbide particles were also observed along the boundaries of prior austenite grains and pockets as well as along the boundaries between δ-ferrite and martensite; thei...","PeriodicalId":20637,"journal":{"name":"PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS WITH HIERARCHICAL STRUCTURE FOR NEW TECHNOLOGIES AND RELIABLE STRUCTURES 2019","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89248063","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}
N. Surikova, V. Panin, N. Narkevich, A. Gordienko, M. Volochaev
{"title":"Mechanisms of deformation of austenitic stainless steel at cold rolling","authors":"N. Surikova, V. Panin, N. Narkevich, A. Gordienko, M. Volochaev","doi":"10.1063/1.5132223","DOIUrl":"https://doi.org/10.1063/1.5132223","url":null,"abstract":"The structure, mechanical characteristics and mechanisms of plastic deformation of stainless austenitic steel 12Cr15Mn9NiCu after high-temperature cross and screw and cold longitudinal rolling are examined with the help of mechanical testing, X-ray diffraction and electron transmission microscopy. It is shown that deformation martensitic transformations are the main mechanisms of deformation at temperatures less than 20 °C. The modes of thermomechanical treatment, which allow to obtain a good combination of strength and plastic properties in steel have been found out.The structure, mechanical characteristics and mechanisms of plastic deformation of stainless austenitic steel 12Cr15Mn9NiCu after high-temperature cross and screw and cold longitudinal rolling are examined with the help of mechanical testing, X-ray diffraction and electron transmission microscopy. It is shown that deformation martensitic transformations are the main mechanisms of deformation at temperatures less than 20 °C. The modes of thermomechanical treatment, which allow to obtain a good combination of strength and plastic properties in steel have been found out.","PeriodicalId":20637,"journal":{"name":"PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS WITH HIERARCHICAL STRUCTURE FOR NEW TECHNOLOGIES AND RELIABLE STRUCTURES 2019","volume":"21 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91424762","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}