On the role of initial void geometry in plastic deformation of metallic thin films: A molecular dynamics study

Su, Yanqing; Xu, Shuozhi

doi:10.1016/j.msea.2016.09.091

Cited by 28 publications

(24 citation statements)

References 39 publications

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“…Overall, a majority of defects nucleate at the top/bottom sides of the void, which is a reflection of the fact that these two sites have the highest stress concentrations in a model subject to a tensile loading along the y direction. We remark that the plastic deformation zone in α-Fe (exhibited by nucleation and evolution of slip bands, full dislocations, and twins) is much more complicated than that in FCC Cu, in which the dislocation nucleation dominates the plasticity [16]. As a result, the development of dislocation density with an increasing strain would not be a good indicator of defect evolution in this work.…”

Section: Defect Nucleation and Evolutionmentioning

confidence: 83%

“…Tang et al [27] similarly reported such a slip-to-twinning transition as the strain rate increases, in a voided BCC Ta model subject to a uniaxial tensile strain or a hydrostatic tensile loading; their MD simulations also revealed a special type of dislocation shear loop at the void surface that can expand as partial or perfect dislocations, evolving into prismatic loops through reaction with each other or developing into twins [28]. However, the atomic-scale mechanisms of the effects of the initial void geometry in nanovoid growth, which have recently been explored in FCC metals [16,19,29], remain largely unknown in BCC metals.…”

Section: Introductionmentioning

confidence: 99%

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Nanovoid growth in BCCα-Fe: influences of initial void geometry

2016

Modelling Simul. Mater. Sci. Eng.

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The growth of voids has a great impact on the mechanical properties of ductile materials by altering their microstructures. Exploring the process of void growth at the nanoscale helps in understanding the dynamic fracture of metals. While some very recent studies looked into the effects of the initial geometry of an elliptic void on the plastic deformation of face-centered cubic metals, a systematic study of the initial void ellipticity and orientation angle in body-centered cubic (BCC) metals is still lacking. In this paper, large scale molecular dynamics simulations with millions of atoms are conducted, investigating the void growth process during tensile loading of metallic thin films in BCC α-Fe. Our simulations elucidate the intertwined influences on void growth of the initial ellipticity and initial orientation angle of the void. It is shown that these two geometric parameters play an important role in the stress-strain response, the nucleation and evolution of defects, as well as the void size/outline evolution in α-Fe thin films. Results suggest that, together with void size, different initial void geometries should be taken into account if a continuum model is to be applied to nanoscale damage progression.

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Section: Defect Nucleation and Evolutionmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Nanovoid growth in BCCα-Fe: influences of initial void geometry

2016

Modelling Simul. Mater. Sci. Eng.

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“…Prior atomistic studies revealed that the nanovoid growth process is affected by many factors, including, but not limited to, strain rate [9], temperature [10], initial porosity [11], initial void shape [12], and crystallographic orientations [13,14,15]. Compared with face-centered cubic (FCC) [1,10,12] and body-centered cubic (BCC) [9,2,11] systems, there exist much fewer studies of nanvoids in metals with a hexagonal close-packed (HCP) lattice, in part due to a lack of reliable interatomic potential and more complicated slip/twinning systems in the latter.…”

Section: Introductionmentioning

confidence: 99%

“…Compared with face-centered cubic (FCC) [1,10,12] and body-centered cubic (BCC) [9,2,11] systems, there exist much fewer studies of nanvoids in metals with a hexagonal close-packed (HCP) lattice, in part due to a lack of reliable interatomic potential and more complicated slip/twinning systems in the latter. Particularly for HCP Mg, the lightest and the third most abundant element in the Earth's crust among all metals, most atomistic simulations in the literature concerned nanocracks [16,17,18,19]; to the best of our knowledge, only a few MD and atomistic-based multiscale studies have been devoted to nanovoids [20,21,22].…”

Section: Introductionmentioning

confidence: 99%

Deformation of periodic nanovoid structures in Mg single crystals

Chavoshi

2018

Mater. Res. Express

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Abstract. Large scale molecular dynamics (MD) simulations in Mg single crystal containing periodic cylindrical voids subject to uniaxial tension along the z direction are carried out. Models with different initial void sizes and crystallographic orientations are explored using two interatomic potentials. It is found that (i) a larger initial void always leads to a lower yield stress, in agreement with an analytic prediction; (ii) orientations, the two potentials identically predict the nucleation of edge dislocations on the prismatic plane, which then glide away from the void, resulting in extrusions at the void surface; in the case of the smallest initial void, these surface extrusions pinch the void into two voids. Besides bringing new physical understanding of the nanovoid structures, our work highlights the variability and uncertainty in MD simulations arising from the interatomic potential, an issue relatively lightly addressed in the literature to date.

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“…On the other hand, nanotwinned small‐sized metallic systems, for example, nanopillars and nanotubes, with either parallel or fivefold CTBs, remain relatively lightly explored . Compared with 3D nanocrystals, 1D nanopillars/nanotubes with free surfaces attain additional geometric features including outer/inner diameter and cross‐sectional shape which, along with the CTB spacing, may significantly alter their mechanical properties . On the other hand, deformation may annihilate nanotwins and increase the CTB spacing .…”

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confidence: 99%

Deformation Mechanisms in Nanotwinned Tungsten Nanopillars: Effects of Coherent Twin Boundary Spacing

Chavoshi

2018

Physica Rapid Research Ltrs

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Nano-scale coherent twin boundaries (CTBs) significantly alter the mechanical and electrical properties of metallic materials. Despite a number of studies of the nanotwinned nanopillars in face-centered cubic metals, investigations of them in body-centered cubic (BCC) systems are rare. In this Letter, we explore the uniaxial deformation mechanisms of BCC tungsten nanopillars containing nano-scale {112} CTBs using molecular dynamics (MD) simulations. Our work reveals a novel tension-compression asymmetric stress-strain response and deformation behavior, in conjunction with the effects of CTB spacing. With a relatively large CTB spacing, the plastic deformation in nanotwinned nanopillars is mainly controlled by dislocation nucleation from surface/CTB intersections, gliding on distant and adjacent slip planes under tensile and compressive loading, respectively; as a result, the tensile yield stress is almost invariant with respect to the CTB spacing, while the compressive yield stress increases with a decreasing CTB spacing. As the CTB spacing reduces to 1 nm, detwinning, exhibited by annihilation of {112} twin layers as a result of partial dislocations gliding on CTBs, is observed in both tension and compression; at higher strains, however, {111} incoherent twin boundaries, whose resistance to cracking contributes to strain hardening, are formed under tensile loading but not under compressive loading.

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On the role of initial void geometry in plastic deformation of metallic thin films: A molecular dynamics study

Cited by 28 publications

References 39 publications

Nanovoid growth in BCCα-Fe: influences of initial void geometry

Nanovoid growth in BCCα-Fe: influences of initial void geometry

Deformation of periodic nanovoid structures in Mg single crystals

Deformation Mechanisms in Nanotwinned Tungsten Nanopillars: Effects of Coherent Twin Boundary Spacing

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