scholarly journals Shape Stability of Metallic Nanoplates: A Molecular Dynamics Study

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Xiwen Chen ◽  
Rao Huang ◽  
Tien-Mo Shih ◽  
Yu-Hua Wen
Keyword(s):  
Molecular Dynamics ◽  
Shear Stress ◽  
Molecular Dynamics Simulations ◽  
Shape Evolution ◽  
Body Centered Cubic ◽  
Shape Stability ◽  
Subsequent Formation ◽  
Dynamics Simulations ◽  
Saddle Shape ◽  
Functional Versatility

AbstractMetallic nanoplates have attracted widespread interests owing to their functional versatility, which relies heavily on their morphologies. In this study, the shape stability of several metallic nanoplates with body-centered-cubic (bcc) lattices is investigated by employing molecular dynamics simulations. It is found that the nanoplate with (110) surface planes is the most stable compared to the ones with (111) and (001) surfaces, and their shapes evolve with different patterns as the temperature increases. The formation of differently orientated facets is observed in the (001) nanoplates, which leads to the accumulation of shear stress and thus results in the subsequent formation of saddle shape. The associated shape evolution is quantitatively characterized. Further simulations suggest that the shape stability could be tuned by facet orientations, nanoplate sizes (including diameter and thickness), and components.

scholarly journals Anisotropic shock responses of nanoporous Al by molecular dynamics simulations

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0247172
Author(s):  
Xia Tian ◽  
Kaipeng Ma ◽  
Guangyu Ji ◽  
Junzhi Cui ◽  
Yi Liao ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Shear Stress ◽  
Molecular Dynamics Simulations ◽  
Dislocation Nucleation ◽  
Shape Evolution ◽  
Mechanical Responses ◽  
Slip Planes ◽  
Dynamics Simulations ◽  
Collapse Rate ◽  
Crystallographic Orientations

Mechanical responses of nanoporous aluminum samples under shock in different crystallographic orientations (<100>, <111>, <110>, <112> and <130>) are investigated by molecular dynamics simulations. The shape evolution of void during collapse is found to have no relationship with the shock orientation. Void collapse rate and dislocation activities at the void surface are found to strongly dependent on the shock orientation. For a relatively weaker shock, void collapses fastest when shocked along the <100> orientation; while for a relatively stronger shock, void collapses fastest in the <110> orientation. The dislocation nucleation position is strongly depended on the impacting crystallographic orientation. A theory based on resolved shear stress is used to explain which slip planes the earliest-appearing dislocations prefer to nucleate on under different shock orientations.

scholarly journals Shear-rate dependence of thermodynamic properties of the Lennard-Jones truncated and shifted fluid by molecular dynamics simulations

2021 ◽  
Author(s):  
Martin P. Lautenschlaeger ◽  
Hans Hasse
Keyword(s):  
Molecular Dynamics ◽  
Shear Stress ◽  
Shear Rate ◽  
Molecular Dynamics Simulations ◽  
Local Structure ◽  
Rate Dependence ◽  
Lennard Jones ◽  
Fluid Properties ◽  
Dynamics Simulations ◽  
Shear Rate Dependence

It was shown recently that using the two-gradient method, thermal, caloric, and transport properties of fluids under quasi-equilibrium conditions can be determined simultaneously from nonequilibrium molecular dynamics simulations. It is shown here that the influence of shear stresses on these properties can also be studied using the same method. The studied fluid is described by the Lennard-Jones truncated and shifted potential with the cut-off radius r*c = 2.5σ. For a given temperature T and density ρ, the influence of the shear rate on the following fluid properties is determined: pressure p, internal energy u, enthalpy h, isobaric heat capacity cp, thermal expansion coefficient αp, shear viscosity η, and self-diffusion coefficient D. Data for 27 state points in the range of T ∈ [0.7, 8.0] and ρ ∈ [0.3, 1.0] are reported for five different shear rates (γ ̇ ∈ [0.1,1.0]). Correlations for all properties are provided and compared with literature data. An influence of the shear stress on the fluid properties was found only for states with low temperature and high density. The shear-rate dependence is caused by changes in the local structure of the fluid which were also investigated in the present work. A criterion for identifying the regions in which a given shear stress has an influence on the fluid properties was developed. It is based on information on the local structure of the fluid. For the self-diffusivity, shear-induced anisotropic effects were observed and are discussed.

scholarly journals Structure and Phase Transition Features of Monoclinic and Tetragonal Phases in U–Mo Alloys

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 515
Author(s):  
Lada Kolotova ◽  
Ilia Gordeev
Keyword(s):  
Phase Transition ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Structural Properties ◽  
Lattice Constant ◽  
Central Atom ◽  
Body Centered Cubic ◽  
Α Phase ◽  
Dynamics Simulations ◽  
Molybdenum Concentration

Using molecular dynamics simulations, we studied the structural properties of orthorhombic, monoclinic, and body-centered tetragonal (bct) phases of U–Mo alloys. A sequence of shear transformations between metastable phases takes place upon doping of uranium with molybdenum from pure α -U: orthorhombic α ′ → monoclinic α ″ → bct γ 0 → body-centered cubic (bcc) with doubled lattice constant γ s → bcc γ . The effects of alloy content on the structure of these phases have been investigated. It has been shown that increase in molybdenum concentration leads to an increase in the monoclinic angle and is more similar to the γ 0 -phase. In turn, tetragonal distortion of the γ 0 -phase lattice with displacement of a central atom in the basic cell along the <001> direction makes it more like the α ″ -phase. Both of these effects reduce the necessary shift in atomic positions for the α ″ → γ 0 -phase transition.

Molecular dynamics simulations of shock-induced deformation twinning of a body-centered-cubic metal

2013 ◽  
Vol 88 (10) ◽  
Author(s):  
A. Higginbotham ◽  
M. J. Suggit ◽  
E. M. Bringa ◽  
P. Erhart ◽  
J. A. Hawreliak ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Deformation Twinning ◽  
Body Centered Cubic ◽  
Dynamics Simulations
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