Deformation of periodic nanovoid structures in Mg single crystals

Xu, Shuozhi; Su, Yanqing; Chavoshi, Saeed Zare

doi:10.1088/2053-1591/aaa678

Cited by 18 publications

(7 citation statements)

References 42 publications

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“…As typical HCP materials, magnesium and magnesium alloys have been widely used in the aerospace, automobile, defense, and medical fields due to their excellent properties of low density and high strength [22][23][24]. In practical engineering materials, the effects of unavoidable or artificial defects, such as voids [25][26][27][28], cracks [29], grain boundaries [30,31], and dislocations [32], on the plasticity of Mg materials, have received extensive attention. For example, Li et al [28] revealed two typical void collapse mechanisms of nanoporous magnesium under shock loading by MD simulations: the plasticity mechanism and the internal jetting mechanism.…”

Section: Introductionmentioning

confidence: 99%

Effect of Vacancies on Dynamic Response and Spallation in Single-Crystal Magnesium by Molecular Dynamic Simulation

Jiang

Jian

Xiao

et al. 2022

Metals

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The effect of vacancies on dynamic response and spallation in single-crystal magnesium (Mg) is investigated by nonequilibrium molecular dynamics simulations. The initial vacancy concentration (Cv) ranges from 0% to 2.0%, and the shock loading is applied along [0001] and [10–10] directions. The simulation results show that the effects of vacancy defects are strongly dependent on the shock directions. For shock along the [0001] direction, vacancy defects have a negligible effect on compression-induced plasticity, but play a role in increasing spall damage. In contrast, for shock along the [10–10] orientation, vacancy defects not only provide the nucleation sites for compression-induced plasticity, which mainly involves crystallographic reorientation, phase transition, and stacking faults, but also significantly reduce spall damage. The degree of spall damage is probably determined by a competitive mechanism between energy absorption and stress attenuation induced by plastic deformation. Void evolution during spallation is mainly based on the emission mechanism of dislocations. The {11–22} <11–23> pyramidal dislocation facilitates the nucleation of void in the [0001] shock, as well as the {1–100} <11–20> prismatic dislocation in the [10–10] shock. We also investigated the variation of spall strength between perfect and defective Mg at different shock velocities. The relevant results can provide a reference for future investigations on spall damage.

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Section: Introductionmentioning

confidence: 99%

Effect of Vacancies on Dynamic Response and Spallation in Single-Crystal Magnesium by Molecular Dynamic Simulation

Jiang

Jian

Xiao

et al. 2022

Metals

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“…25 We use an embedded-atom method potential 26 known to well describe the generalized stacking fault energies, which are important for plastic deformation mechanisms including dislocation slip and twinning. [27][28][29][30] The lattice parameter is 3.143 39 Å. In all simulations, an NPT ensemble and an NVT ensemble are applied, respectively, to the bulk single crystals and the NTs/NWs, with a constant time step size of 2 fs at 300 K. Each model initially undergoes a dynamic relaxation for 250 ps, followed by tensile deformation along the z direction with a constant engineering strain rate _ ε ¼ 10 8 s À1 .…”

Section: Methodsmentioning

confidence: 99%

Atomistic simulations of tungsten nanotubes under uniform tensile loading

Trusty

Beyerlein

2019

Journal of Applied Physics

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Metallic nanotubes (NTs) have gained much attention in recent years due to their exciting potential to be just as strong or even stronger than their heavier counterparts, nanowires (NWs), with the same outer radius. Unlike NWs, NTs have inner wall diameter and wall thickness parameters that can be engineered to provide advantage in structural materials design. In this work, molecular dynamics is used to quantify the combined effects of NT specific dimensions, outer radius and wall thickness, on the tensile strength of single crystalline tungsten NTs at room temperature. Uniaxial tensile simulations are carried out for three different crystallographic orientations along the NT axis-two known as brittle orientations and one as ductile orientation. For these three orientations, the strength of NTs can be made higher than NWs, for the same outer radius, as the wall thickness decreases. The calculations indicate that even for the brittle orientations, NTs can be engineered to be more ductile by tuning the outer radius and the wall thickness.

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“…24 As the validity of MD simulations considerably hinges on the choice of interatomic potential, it is crucial to employ an appropriate interatomic potential so as to attain accurate results. [25][26][27][28][29][30] Atomic interactions of SiC are modelled using the effective many-body interatomic potential developed by Vashishta et al, 31 which is capable of reasonably reproducing the generalized stacking fault energies, cohesive energy, elastic constants, and melting point of 3C-SiC. The initial nanocrystalline structure is generated using the Voronoi tessellated method.…”

Section: Simulation Methodologymentioning

confidence: 99%

Tension-compression asymmetry in plasticity of nanotwinned 3C-SiC nanocrystals

Chavoshi

2018

Journal of Applied Physics

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Encompassing nanoscale thin twins in metals induces diverse influences, either strengthening triggered by the lattice dislocation blockage effects or softening prompted by dislocation emission from coherent twin boundary (CTB)/grain boundary (GB) intersections as well as CTB migration; yet the deformation mechanism remains poorly understood in ceramic nanostructures possessing covalent bonds. Here, we report the results of uniaxial compressive and tensile stress loading of twin-free and nanotwinned nanocrystalline cubic silicon carbide (3C-SiC) ceramic attained by large-scale molecular dynamics simulations. We find a strong and unique tension-compression asymmetry in strength of nanocrystalline ceramics, much higher than that of metals. We demystify that strength and ductility behaviour do not correlate simply with the amount of dislocation density, voids, intergranular disordered phase, and total strain energy; instead, it arises from a complex interplay of the aforementioned features and structural characteristics, e.g., GB and triple junction area distribution along/normal to the direction of straining as well as the capability of strain accommodation by the GBs and CTBs, with the dominant role of the structural characteristics in nanotwinned samples. Our results also reveal that primarily intergranular crack propagation and fracture along the GBs transpires, and not along the CTBs, resulting from the high energy of the GBs. However, a high density of nanoscale twins in the 3C-SiC nanocrystals could give rise to the alternation of the crack path from intergranular to intragranular type induced by shear, which brings about the glide of Shockley partials along the CTBs and subsequent formation of CTB steps and twin plane migration.

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Deformation of periodic nanovoid structures in Mg single crystals

Cited by 18 publications

References 42 publications

Effect of Vacancies on Dynamic Response and Spallation in Single-Crystal Magnesium by Molecular Dynamic Simulation

Effect of Vacancies on Dynamic Response and Spallation in Single-Crystal Magnesium by Molecular Dynamic Simulation

Atomistic simulations of tungsten nanotubes under uniform tensile loading

Tension-compression asymmetry in plasticity of nanotwinned 3C-SiC nanocrystals

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