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  • 1.
    Delandar, Arash Hosseinzadeh
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.
    Modeling defect structure evolution in spent nuclear fuel container materials2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Materials intended for disposal of spent nuclear fuel require a particular combination of physical and chemical properties. The driving forces and mechanisms underlying the material’s behavior must be scientifically understood in order to enable modeling at the relevant time- and length-scales. The processes that determine the mechanical behavior of copper canisters and iron inserts, as well as the evolution of their mechanical properties, are strongly dependent on the properties of various defects in the bulk copper and iron alloys.

    The first part of the present thesis deals with precipitation in the cast iron insert. A nodular cast iron insert will be used as the inner container of the spent nuclear fuel. Precipitation is investigated by computing effective interaction energies for point defect pairs (solute–solute and vacancy–solute) in bcc iron using first-principles calculations. The main considered impurities in the iron matrix include 3sp (Si, P, S) and 3d (Cr, Mn, Ni, Cu) solute elements. By computing interaction energies possibility of formation of different second phase particles such as late blooming phases (LBPs) in the cast iron insert is evaluated.

    The second part is devoted to the fundamentals of dislocations and their role in plastic deformation of metals. Deformation of single-crystal copper under high strain rates is simulated by employing dislocation dynamics (DD) method to examine the effect of strain rate on mechanical properties as well as dislocation microstructure development.

    Creep deformation of copper canister at low temperatures is studied. The copper canister will be used in the long-term storage of spent nuclear fuel as the outer shell of the waste package to provide corrosion protection. A glide rate is derived based on the assumption that at low temperatures it is controlled by the climb rate of jogs on the dislocations. Using DD simulation creep deformation of copper at low temperatures is modeled by taking glide but not climb into account. Moreover, effective stresses acting on dislocations are computed using the data extracted from DD simulations.

  • 2.
    Delandar, Arash Hosseinzadeh
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Gorbatov, O. I.
    Gornostyrev, Yu. N.
    Korzhavyi, Pavel A.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Ab-initio based search for late blooming phase compositions in iron alloysManuscript (preprint) (Other academic)
  • 3.
    Delandar, Arash Hosseinzadeh
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Gorbatov, O. I.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Applied Physics, Division of Materials Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, 97187 Luleå, Sweden; Laboratory for Mechanics of Gradient Nanomaterials, Nosov Magnitogorsk State Technical University, 455000 Magnitogorsk, Russia.
    Selleby, Malin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Gornostyrev, Y. N.
    Korzhavyi, Pavel A.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    End-member compounds of a 4-sublattice model of multicomponent BCC solid solutions2018In: Data in Brief, E-ISSN 2352-3409, Vol. 20, p. 1018-1022Article in journal (Refereed)
    Abstract [en]

    The article presents ab initio calculated properties (total energies, lattice parameters, and elastic properties) for the complete set of 1540 end-member compounds within a 4-sublattice model of Fe-based solid solutions. The compounds are symmetry-distinct cases of integral site occupancy for superstructure Y (space group #227, type LiMgPdSn) chosen to represent the ordered arrangements of solvent atoms (Fe), solute atoms (Fe, Mg, Al, Si, P, S, Mn, Ni, Cu), and vacancies (Va) on the sites of a body-centered cubic lattice. The model is employed in the research article “Ab-initio based search for late blooming phase compositions in iron alloys” (Hosseinzadeh et al., 2018) [1].

  • 4.
    Delandar, Arash Hosseinzadeh
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Gorbatov, O. I.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Multiscale Materials Modelling. Applied Physics, Division of Materials Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, 97187, Luleå, Sweden; Laboratory for Mechanics of Gradient Nanomaterials, Nosov Magnitogorsk State Technical University, 455000, Magnitogorsk, Russia.
    Selleby, Malin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Gornostyrev, Yu. N.
    Ryssland.
    Korzhavyi, Pavel A.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. National University of Science and Technology ”MISiS”, 119049, Moscow, Russia.
    Ab-initio based search for late blooming phase compositions in iron alloys2018In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 509, p. 225-236Article in journal (Refereed)
    Abstract [en]

    We present a systematic analysis, based on ab initio calculations, of concentrated solute arrangements and precipitate phases in Fe-based alloys. The input data for our analysis are the calculated formation and interaction energies of point defects in the iron matrix, as well as the energies of ordered compounds that represent end-members in the 4-sublattice compound energy model of a multicomponent solid solution of Mg, Al, Si, P, S, Mn, Ni, and Cu elements and also vacancies in bcc Fe. The list of compounds also includes crystal structures obtained by geometric relaxation of the end-member compounds that in the cubic structure show weak mechanical instabilities (negative elastic constants) and also the G-phase Mn-6(Ni,Fe)(16)(Si,P)(7) having a complex cubic structure. A database of calculated thermodynamic properties (crystal structure, molar volume, enthalpy of formation, and elastic constants) of the most stable late-blooming-phase candidates is thus obtained. The results of this ab initio based theoretical analysis compare well with the recent experimental observations and predictions of thermodynamic calculations employing Calphad methodology.

  • 5.
    Delandar, Arash Hosseinzadeh
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Haghighat, Seyed Masood Hafez
    Korzhavyi, Pavel
    Sandström, Rolf
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Dislocation dynamics modeling of plastic deformation in single-crystal copper at high strain rates2016In: International Journal of Materials Research - Zeitschrift für Metallkunde, ISSN 1862-5282, E-ISSN 2195-8556, Vol. 107, no 11, p. 988-995Article in journal (Refereed)
    Abstract [en]

    Tensile deformation of single-crystal copper along [001] orientation is modeled. Single crystal is deformed at three sets of high strain rates, ranging from 10(3) to 10(5) s(-1), using the three-dimensional dislocation dynamics technique to simulate dislocation microstructure evolution and the resultant macroscopic response. Two initial dislocation configurations consisting of straight dislocations and Frank-Read sources are randomly distributed over the simulation volume with an edge length of 1 mu m. For both initial setups, the mechanical response of the single crystal to the external loading demonstrates a considerable effect of strain rate. In addition, strain rate influences dislocation density evolution and consequently development of the dislocation microstructure. At all applied strain rates for both initial dislocation setups, dislocations evolve into a heterogeneous microstructure and this heterogeneity increases with plastic strain and strain rate.

  • 6.
    Delandar, Arash Hosseinzadeh
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Sandström, Rolf
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Korzhavyi, Pavel A.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    The role of glide during creep of copper at low temperaturesManuscript (preprint) (Other academic)
  • 7.
    Delandar, Arash Hosseinzadeh
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Sandström, Rolf
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.
    Korzhavyi, Pavel A.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    The Role of Glide during Creep of Copper at Low Temperatures2018In: METALS, ISSN 2075-4701, Vol. 8, no 10, article id 772Article in journal (Refereed)
    Abstract [en]

    Copper canister will be used in Scandinavia for final storage of spent nuclear fuel. The copper will be exposed to temperatures of up to 100 degrees C. The creep mechanism at near ambient temperatures has been assumed to be glide of dislocations, but this has never been verified for copper or other materials. In particular, no feasible mechanism for glide based static recovery has been proposed. To attack this classical problem, a glide mobility based on the assumption that it is controlled by the climb of the jogs on the dislocations is derived and shown that it is in agreement with observations. With dislocation dynamics (DD) simulations taking glide but not climb into account, it is demonstrated that creep based on glide alone can reach a quasi-stationary condition. This verifies that static recovery can occur just by glide. The DD simulations also show that the internal stress during creep in the loading direction is almost identical to the applied stress also directly after a load drop, which resolves further classical issues.

  • 8.
    Gorbatov, Oleg I.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Institute of Quantum Materials Science, Russian Federation; Nosov Magnitogorsk State Technical University, Russian Federation.
    Delandar, Arash Hosseinzadeh
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Gornostyrev, Y. N.
    Ruban, Andrei V.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. ENHETEN EGENSKAPER.
    Korzhavyi, Pavel A.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    First-principles study of interactions between substitutional solutes in bcc iron2016In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 475, p. 140-148Article in journal (Refereed)
    Abstract [en]

    Using density functional theory based calculations, employing the locally self-consistent Green's function method and the projected augmented wave method, we develop a database of solute-solute interactions in dilute alloys of bcc Fe. Interactions within the first three coordination shells are computed for the ferromagnetic state as well as for the paramagnetic (disordered local moment) state of the iron matrix. The contribution of lattice relaxations to the defect interaction energy is investigated in the ferromagnetic state. Implications of the obtained results for modeling the phenomena of point defect clustering and phase precipitation in bcc Fe-based alloys and steel are discussed.

  • 9.
    Hosseinzadeh Delandar, Arash
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.
    Numerical Modeling of Plasticity in FCC Crystalline Materials Using Discrete Dislocation Dynamics2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Plasticity in crystalline solids is controlled by the microscopic line defects known as “dislocations”. Decisive role of dislocations in crystal plasticity in addition to fundamentals of plastic deformation are presented in the current thesis work. Moreover, major features of numerical modeling method “Discrete Dislocation Dynamics (DDD)” technique are described to elucidate a powerful computational method used in simulation of crystal plasticity.

    First part of the work is focused on the investigation of strain rate effect on the dynamic deformation of crystalline solids. Single crystal copper is chosen as a model crystal and discrete dislocation dynamics method is used to perform numerical uniaxial tensile test on the single crystal at various high strain rates. Twenty four straight dislocations of mixed character are randomly distributed inside a model crystal with an edge length of 1 µm subjected to periodic boundary conditions. Loading of the model crystal with the considered initial dislocation microstructure at constant strain rates ranging from 103 to 105s1 leads to a significant strain rate sensitivity of the plastic flow. In addition to the flow stress, microstructure evolution of the sample crystal demonstrates a considerable strain rate dependency. Furthermore, strain rate affects the strain induce microstructure heterogeneity such that more heterogeneous microstructure emerges as strain rate increases.

    Anisotropic characteristic of plasticity in single crystals is investigated in the second part of the study. Copper single crystal is selected to perform numerical tensile tests on the model crystal along two different loading directions of [001] and [111] at two high strain rates. Effect of loading orientation on the macroscopic behavior along with microstructure evolution of the model crystal is examined using DDD method. Investigation of dynamic response of single crystal to the mechanical loading demonstrates a substantial effect of loading orientation on the flow stress. Furthermore, plastic anisotropy is observed in dislocation density evolution such that more dislocations are generated as straining direction of single crystal is changed from [001] to [111] axis. Likewise, strain induced microstructure heterogeneity displays the effect of loading direction such that more heterogeneous microstructure evolve as single crystal is loaded along [111] direction. Formation of slip bands and consequently localization of plastic deformation are detected as model crystal is loaded along both directions.

  • 10.
    Hosseinzadeh Delandar, Arash
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.
    Hafez Haghigha, S. M.
    Korzhavyi, Pavel
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.
    Sandström, Rolf
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.
    Three-dimensional dislocation dynamics simulation of plastic deformation in copper single crystalManuscript (preprint) (Other academic)
    Abstract [en]

    Dynamic deformation of single crystal copper at high strain rates ranging from 103 to 105 s-1 is modeled using three dimensional discrete dislocation dynamics method. Numerical uniaxial tensile test is performed on a model crystal along [0 0 1] orientation to examine the resulting macroscopic behavior along with microstructure evolution at high strain rates. Twenty-four straight dislocations of mixed character are randomly distributed inside a model crystal with an edge length of 1  subjected to period boundary conditions. In the simulated single crystal with the considered initial dislocation microstructure, plastic flow demonstrates a significant strain rate dependency at imposed strain rates. Rate sensitivity of flow stress observed at strain rates >> 103 s-1 agrees well with the reported experimental studies on copper single crystal.  Furthermore, strain rate considerably affects the microstructure evolution of the sample crystal as a result of influence of strain rate on dislocations generation and interactions. Formation of heterogeneous microstructure is observed at all imposed strain rates. We find that heterogeneity of microstructure escalates as strain rate increases.

  • 11.
    Hosseinzadeh Delandar, Arash
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.
    Korzhavyi, Pavel
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.
    Sandström, Rolf
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.
    Investigation of loading orientation effect on dynamic deformation of single crystal copper at high strain rates: Discrete dislocation dynamics studyManuscript (preprint) (Other academic)
    Abstract [en]

    Uniaxial tensile loading of copper single crystal along [001] and [111] orientations is modeled at two high strain rates of 105 and 106 s-1. Discrete dislocation dynamics method is used to study the anisotropic characteristic of plastic deformation in the model crystal. Furthermore, strain rate sensitivity of the flow stress in copper crystal is examined. Investigation of mechanical response of single crystal to the external loading demonstrates a substantial effect of loading orientation on the plastic flow. We find that at both imposed strain rates flow stress increases significantly when tensile load is applied along [111] crystallographic axis. Similarly, plastic anisotropy is observed in dislocation density evolution such that more dislocations are generated as straining direction of single crystal is changed from [001] to [111] axis. Moreover, plastic flow behavior exhibits a profound strain rate sensitivity at both loading orientations which agrees well with experimental observations regarding strain rate dependency of flow stress in copper single crystal as strain rate exceeds 103 s-1. At both applied strain rates dislocations evolve into a heterogeneous microstructure and highest heterogeneity is observed as model crystal is loaded along [111] direction at strain rate of    106 s-1. Formation of slip bands and consequently localization of plastic deformation are detected for all considered cases. However, at the higher strain rate of 106 s-1, slip band formation is more pronounced for both loading orientations.

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