Superelasticity in bcc nanowires by a reversible twinning mechanism

Li, Suzhi; Ding, Xiangdong; Deng, Jianqiang; Lookman, Turab; Ju, Li; Ren, Xiaobing; Sun, Jun; Saxena, Avadh

doi:10.1103/physrevb.82.205435

Cited by 107 publications

(113 citation statements)

References 43 publications

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“…In addition to perfect nanowires, deformation by twinning is also observed in surface coated Fe 12 and Fe-Cr 13 nanowires. It is interesting to note that when the BCC Fe nanowire deforms by the twinning mechanism, it has been found to undergo reorientation 14,15 and exhibit the shape memory effect and pseudo-elasticity [15][16][17][18] . These mechanisms cannot be observed when the nanowires deform by the dislocation slip.…”

Section: Introductionmentioning

confidence: 99%

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Atomistic simulations on ductile-brittle transition in ⟨111⟩ BCC Fe nanowires

Sainath

Choudhary

2017

Journal of Applied Physics

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Molecular dynamics simulations have been performed to understand the influence of temperature on the tensile deformation and fracture behavior of <111> BCC Fe nanowires. The simulations have been carried out at different temperatures in the range 10-1000 K employing a constant strain rate of 1× 10 8 s −1 . The results indicate that at low temperatures (10-375 K), the nanowires yield through the nucleation of a sharp crack and fails in brittle manner. On the other hand, nucleation of multiple 1/2<111> dislocations at yielding followed by significant plastic deformation leading to ductile failure has been observed at high temperatures in the range 450-1000 K. At the intermediate temperature of 400 K, the nanowire yields through nucleation of crack associated with many mobile 1/2<111> and immobile <100> dislocations at the crack tip and fails in ductile manner. The ductile-brittle transition observed in <111> BCC Fe nanowires is appropriately reflected in the stress-strain behavior and plastic strain at failure. The ductile-brittle transition increases with increasing nanowire size. The change in fracture behavior has been discussed in terms of the relative variations in yield and fracture stresses and change in slip behavior with respect to temperature. Further, the dislocation multiplication mechanism assisted by the kink nucleation from the nanowire surface observed at high temperatures has been presented.

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Section: Introductionmentioning

confidence: 99%

“…Most of these studies in BCC metallic nanowires have been focused mainly on deformation aspects such as twinning and dislocation behavior [8][9][10][11][12][13][14][15][16][17][18][19][20] . It is surprising that enough attention has not been paid towards the fracture behavior of BCC Fe nanowires.…”

Section: Introductionmentioning

confidence: 99%

Atomistic simulations on ductile-brittle transition in ⟨111⟩ BCC Fe nanowires

Sainath

Choudhary

2017

Journal of Applied Physics

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“…Отметим, что величина пороговой деформации, полученная в данной работе, существенно превосходит соответ-ствующее значение для макроскопических по раз-меру образцов. При этом интервал упругой облас-ти для микроскопических по размеру образцов может достигать 10% деформации и более [21].…”

Section: механическое нагружение кристаллитовunclassified

Md Simulation of Plastic Deformation Nucleation in Stressed Crystallites Under Irradiation

Korchuganov

Zolnikov

Крыжевич

et al. 2015

PAST-TF

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Изучение механизмов зарождения пластической деформации в металлах и сплавах при облучении и механическом нагружении является актуальной задачей материаловедения. Исследованы особенности зарождения и развития дефектной структуры в ме-ханически нагруженных кристаллитах железа, ванадия и меди при радиационном облучении. Расчёты проводились на основе молекулярно-динамического подхода. Механическое нагружение осуществлялось таким образом, чтобы объём моделируемого кристаллита оставался постоянным. Энергия первично-выбитого атома, формирующего каскад атомных смещений в нагружен-ном кристаллите, варьировалась в интервале от 0,05 до 50 кэВ. Каскады атомных смещений могут вызывать масштабные струк-турные перестройки в зоне значительно большей, чем радиационно-повреждённая область. Такие структурные перестройки аналогичны тем, что происходят при механическом нагружении образцов. В железе и ванадии они реализуются на основе меха-низма двойникования, в меди -посредством зарождения петель частичных дислокаций.Ключевые слова: кристаллы железа, ванадия, меди, механические напряжения, облучение, каскады атомных смещений, пла-стическая деформация, молекулярная динамика. Investigation of plasticity nucleation in metals and alloys under irradiation and mechanical loading is one of the actual problems of materials science. Features of nucleation and evolution of defect system in stressed iron, vanadium and copper crystallites under irradiation are studied by molecular dynamics simulations. Crystallite volume was constant during deformation of specimens. Energy of primary knock-on atom forming atomic displacement cascade in stressed specimens is varied from 0.05 to 50 keV. It was found that atomic displacement cascades in such crystallites may cause global structural changes in region greater than radiation damaged zone. These changes are similar to ones taking place during mechanical loading of specimens. They are realized by twinning in iron and vanadium and by formation of partial dislocation loops in copper. MD SIMULATION OF PLASTIC DEFORMATION NUCLEATION IN STRESSED CRYSTALLITES UNDER IRRADIATIONKey words: iron, vanadium, copper crystals, mechanical stresses, irradiation, atomic displacement cascades, plastic deformation, molecular dynamics. ВВЕДЕНИЕСоздание конструкционных материалов для ядерных и термоядерных реакторов требует детального изучения характера и особенностей структурных изменений в материалах на атомном уровне при меха-нических, термических и радиационных воздействиях. Это объясняется тем, что формирование дефект-ной структуры, которое впоследствии ведёт к изменению эксплуатационных свойств, начинается на атомном уровне [1]. Следует отметить, что высокоэнергетические динамические нагрузки и необходи-мость высокого пространственного и временного разрешения не позволяют экспериментально отслежи-вать зарождение и эволюцию структурных изменений на микроуровне. В связи с этим результаты ком-пьютерного моделирования, как правило, являются единственным источником информации о процессах, протекающих в исследуемых материа...

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“…64 In the case of h ¼ 0 , deformation twins nucleate primarily from the intersections of the free surface and atomic drive walls at the ends of the nanopillar (in both grains) by emitting twin partials on adjacent {112} planes, starting with thin, short, twin embryos 65 (3 ps, Fig. 3(a)).…”

Section: Nucleation and Propagation Of Twinsmentioning

confidence: 99%

Grain boundary orientation effects on deformation of Ta bicrystal nanopillars under high strain-rate compression

Wang

Zhao

Cai

et al. 2014

Journal of Applied Physics

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Layer thickness dependent tensile deformation mechanisms in sub-10nm multilayer nanowires J. Appl. Phys. 111, 124313 (2012) We investigate grain boundary (GB) orientation effects on deformation of Ta bicrystal nanopillars under high strain-rate, uniaxial compression with molecular dynamics simulations. The GB is of the h110i90 twist grain boundary type. We vary the angle between the GB normal and the loading direction (h) in the range of 0 -90 while keeping the GB type unchanged. The GB orientation has strong effects on deformation mechanism, yield stress, failure strain, and dynamics, due to the combined effects of Schmid factors in constituent crystals and resolved shear stress on the GB plane. Single crystal plasticity and GB deformation are competing factors, and the GB-initiated deformation mechanisms (stacking faults vs. twinning, and GB sliding) depend on the local stress level around the GB. The large Schmid factors in constituent single crystals for h ¼ 0 lead to twinning in the single crystals and the lowest yield stress; the ensuing GB deformation is achieved via stacking fault formation due to premature stress relaxation. However, nanopillar deformation in the cases of higher angles is dominated by GB deformation largely in the form of twinning, driven by enhanced stress buildup. GB-initiated deformation in the high Schmid factor nanocrystal precedes and may drive that in the low Schmid factor nanocrystal. The details of twin/stacking fault nucleation and growth/shrinking, twin-twin interaction, and twin-GB interaction are also discussed. V C 2014 AIP Publishing LLC. [http://dx

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Superelasticity in bcc nanowires by a reversible twinning mechanism

Cited by 107 publications

References 43 publications

Atomistic simulations on ductile-brittle transition in ⟨111⟩ BCC Fe nanowires

Atomistic simulations on ductile-brittle transition in ⟨111⟩ BCC Fe nanowires

Md Simulation of Plastic Deformation Nucleation in Stressed Crystallites Under Irradiation

Grain boundary orientation effects on deformation of Ta bicrystal nanopillars under high strain-rate compression

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