Phase stability under irradiation: Ballistic effects

Martin, G.

doi:10.1103/physrevb.30.1424

Cited by 464 publications

(242 citation statements)

References 56 publications

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“…We assume here that Fick's law is valid for ballistic processes as well, which may not be strictly true. Martin 45 performed a numerical evaluation of the validity of Fick's law in the presence of ballistic jumps, and found that if jumps occurred to the third nearest neighbor, Fick's law was found not to be valid for wavelengths smaller than 15 lattice parameters, which is certainly in the range of some of the diffusion processes considered here. While recognizing these limitations, we use the current assumption for simplicity, and we will show later that this assumption has some validity.…”

Section: Amorphization Mechanismmentioning

confidence: 99%

Phase formation in Zr–Fe multilayers: Effect of irradiation

Motta

Paesano

Birtcher

et al. 1999

Journal of Applied Physics

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We have conducted a detailed in situ study of phase formation in Zr-Fe metallic multilayers using irradiation and thermal annealing. Metallic multilayers with near equiatomic and Fe-rich overall compositions and with repetition thicknesses ranging from 7.4 to 33 nm were either irradiated with 300 keV Kr ions at various temperatures ͑from 17 to 623 K͒ or thermally annealed at 773 K while being observed in situ. The kinetics of multilayer reaction were monitored by following the diffraction patterns. For near equiatomic samples, irradiation causes complete amorphization. The dose to amorphization increases in proportion to the square of the wavelength, indicating a process controlled by atomic transport. Amorphization was also achieved by 900 keV electron irradiation at 25 K showing that displacement cascades are not required. The critical dose to amorphization was independent of temperature below room temperature and decreased above room temperature. The activation energy for this second process is 0.17 eV. For the temperature range studied, diffraction from Zr disappears first, indicating that amorphization takes place in the Zr layer by atomic transport of Fe from the Fe layers. These results are consistent with a combination of simple ballistic mixing at low temperature and either simple diffusion or radiation-enhanced diffusion at higher temperatures. Thermal annealing of the equiatomic samples at 773 K produced the same reaction products with slower kinetics. Ion irradiation of Fe-rich samples did not cause complete amorphization and intermetallic compounds Zr 3 Fe and ZrFe 2 were observed in longer wavelength samples. Amorphization of Fe-rich samples was more sluggish, likely because there was competition with formation of other phases. The reaction kinetics were not proportional to square of wavelength for Fe-rich samples, indicating a process that depends on more than atomic transport. Thermal annealing at 773 K of a long wavelength, 57% Fe sample resulted in intermetallic compounds Zr 3 Fe and ZrFe 2 which amorphized during subsequent irradiation. The ease of amorphization of equiatomic samples relative to Fe-rich samples can be explained by a narrower, single minimum free energy curve for the amorphous phase.

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Section: Amorphization Mechanismmentioning

confidence: 99%

Phase formation in Zr–Fe multilayers: Effect of irradiation

Motta

Paesano

Birtcher

et al. 1999

Journal of Applied Physics

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“…Важливою задачею їх дослідження є виявлення керувальних параметрів, відповідальних за процеси самоорганізації, пов'язаних із структуроутворенням [8,9], мікроструктурними перетвореннями [2], фазовими переходами та фазовим розшаруванням [10][11][12].…”

Section: радіяційно-стимульовані ефекти в опромінюваних матеріялахunclassified

“…Було виявлено, що такий процес реалізується при енергіях до декількох десятків кеВ та пригнічується із зростанням енергії електронів. Теоретично та шляхом числового моделювання ефект фіксованого інтервалу температур для фазового розшаруван-ня було виявлено у роботах [10][11][12] (див. рис.…”

Section: мікроструктурні перетворення в об'ємі матеріялівunclassified

“…Модель балістичної дифузії радіяційно-стимульованого атомового перемішування. При теоретичному дослідженні бінарних стопів, підданих дії опромінення, вперше Мартаном було показано, що вплив опромінення можна описати уведенням у розгляд потоку до-даткового атермічного перемішування, викликаного лише перемі-щеннями атомів зі своїх положень (балістичною дифузією) [10]. Пі-зніше цю ідею було використано при конструюванні мікроскопічної теорії упорядкування [11,12].…”

Section: фазово-польові підходи опису мікроструктурних змінunclassified

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Modelling of Microstructural Transformations in the Systems Subject to Radiation Influence

2012

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Розвинуто формалізм для послідовного опису мікроструктурних перетво-рень і фазового розшарування у системах, що перебувають у сильно нерів-новажних умовах, викликаних дією опромінення. Аналізу проведено в ра-мках методи фазового поля кристалу, що дає змогу проводити дослідження на просторових масштабах молекулярної динаміки, однак на часових інте-рвалах дифузійної динаміки. Виявлено умови перебігу мікроструктурних перетворень у періодичних однокомпонентних системах кристалічного ти-пу за наявности конкурувальних стохастичних потоків: термічно стиму-льованого та балістичного перемішування атомів. Аналізою поведінки сис-тем на більш високому ієрархічному рівні для бінарних систем еквіатомо-вого складу встановлено реверсивний характер перебігу процесу фазового розшарування. Для систем із несумірними часовими масштабами розпо-всюдження збурень, що характеризуються ефектами пам'яті, виявлено присутність процесів відбору структур за наявности флюктуацій довжин стрибків атомів, вибитих високоенергетичними частинками.Formalism is developed for description of microstructure transformations and phase separation in systems under irradiation. Investigation is made within the scope of the crystal phase-field method. This approach allows one to simulate materials on the molecular-dynamics spatial scales but on the diffusivedynamics temporal scales. Considering a model for a periodic one-component system driven by both competing stochastic fluxes-thermally-stimulated and external ballistic mixing flues of atoms, conditions of microstructuretransformations' appearance are determined. Analysis of the system on a mesoscopic level for a binary equiatomic system is performed. Reentrant character of phase-separation process is revealed. For systems with transient dynamics, for instance, with incommensurable time scales of propagation of disturbances, which are characterized by the memory effects, at presence of fluc- Fiz. Met. 2012, т. 13, сс. 101-187 Оттиски доступны непосредственно от издателя Фотокопирование разрешено только в соответствии с лицензией © 2012 ИМФ (Институт металлофизики им. Г. В. Курдюмова НАН Украины) Напечатано в Украине.

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“…Therefore, the GB sliding event that was observed for Σ5(210) GB with a high level of SIA content at ambient temperature in return emphasized the role of SIAs and their associated change of local GB structure. The concept of "efficient temperature" ( eff ) has been recently proposed for materials under severe irradiation [55] and severe plastic deformation [56,57]. According to this notion, if the atomic movements driven by deformation or irradiation were higher in comparison with the conventional thermal diffusion, the material could be forced to undergo a state which is equivalent to that at a certain increased (efficient) temperature eff .…”

Section: Remarks and Conclusionmentioning

confidence: 99%

Evaluation of Mechanical Properties of Σ5(210)/[001] Tilt Grain Boundary with Self-Interstitial Atoms by Molecular Dynamics Simulation

Zhang

Lü

Pei

et al. 2017

Journal of Nanomaterials

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Grain boundary (GB) can serve as an efficient sink for radiation-induced defects, and therefore nanocrystalline materials containing a large fraction of grain boundaries have been shown to have improved radiation resistance compared with their polycrystalline counterparts. However, the mechanical properties of grain boundaries containing radiation-induced defects such as interstitials and vacancies are not well understood. In this study, we carried out molecular dynamics simulations with embedded-atom method (EAM) potential to investigate the interaction of Σ5(210)/[001] symmetric tilt GB in Cu with various amounts of self-interstitial atoms. The mechanical properties of the grain boundary were evaluated using a bicrystal model by applying shear deformation and uniaxial tension. Simulation results showed that GB migration and GB sliding were observed under shear deformation depending on the number of interstitial atoms that segregated on the boundary plane. Under uniaxial tension, the grain boundary became a weak place after absorbing self-interstitial atoms where dislocations and cracks were prone to nucleate.

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Phase stability under irradiation: Ballistic effects

Cited by 464 publications

References 56 publications

Phase formation in Zr–Fe multilayers: Effect of irradiation

Phase formation in Zr–Fe multilayers: Effect of irradiation

Modelling of Microstructural Transformations in the Systems Subject to Radiation Influence

Evaluation of Mechanical Properties of Σ5(210)/[001] Tilt Grain Boundary with Self-Interstitial Atoms by Molecular Dynamics Simulation

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