Deformation mechanisms and slip-twin interactions in nanotwinned body-centered cubic iron by molecular dynamics simulations

The mechanical behaviour of nanoporous gold has so far been the subject of studies for bicontinuous morphologies, while the load transfer between ligaments is the primary challenge for using nanoporous structures—especially membranes with nanopores—in single-molecule sensors. This work studies the pore shape effect on deformation mechanisms of nanoporous gold membranes through molecular dynamics simulations. Tension and compression tests are carried out for nanoporous gold with circular, elliptical, square and hexagonal pore shapes. A significant pore shape effect on the mechanical properties is observed with distinct load transfer capabilities. A uniform stress transfer between ligaments constitutes a distinguished set of mechanical responses for structures with the hexagonal pore shape under tension, while a unique stress distribution in nanoporous with the circular pore shape introduces a high strength and ductile structure under compression. Further to shed light on the existing experimental observations, this work provides a comprehensive study on load transfer capabilities in the mechanical behaviour of nanoporous gold for sensing applications.

Download Full-text

Influence of Temperature on Mechanical Properties of Nanocrystalline 316L Stainless Steel Investigated via Molecular Dynamics Simulations

Materials ◽

10.3390/ma13122803 ◽

2020 ◽

Vol 13 (12) ◽

pp. 2803 ◽

Cited By ~ 2

Author(s):

Abdelrahim Husain ◽

Peiqing La ◽

Yue Hongzheng ◽

Sheng Jie

Keyword(s):

Mechanical Properties ◽

Molecular Dynamics ◽

Grain Size ◽

Stainless Steel ◽

Molecular Dynamics Simulations ◽

Yield Stress ◽

316L Stainless Steel ◽

Deformation Mechanisms ◽

Grain Sizes ◽

Dynamics Simulations

Molecular dynamics simulations were conducted to study the mechanical properties of nanocrystalline 316L stainless steel under tensile load. The results revealed that the Young’s modulus increased with increasing grain size below the critical average grain size. Two grain size regions were identified in the plot of yield stress. In the first region, corresponding to grain sizes above 7.7 nm, the yield stress decreased with increasing grain size and the dominant deformation mechanisms were deformation twinning and extended dislocation. In the second region, corresponding to grain sizes below 7.7 nm, the yield stress decreased rapidly with decreasing grain size and the dominant deformation mechanisms were grain boundary sliding and also grain rotation. The yield strength and Young’s modulus were both found to decrease with increasing temperature, which increased the interatomic distance and thereby decreased the interatomic bonding force.

Download Full-text

Shape Stability of Metallic Nanoplates: A Molecular Dynamics Study

Nanoscale Research Letters ◽

10.1186/s11671-019-3192-7 ◽

2019 ◽

Vol 14 (1) ◽

Cited By ~ 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.

Download Full-text

The Plastic Deformation Mechanisms of hcp Single Crystals with Different Orientations: Molecular Dynamics Simulations

Materials ◽

10.3390/ma14040733 ◽

2021 ◽

Vol 14 (4) ◽

pp. 733

Author(s):

Zhi-Chao Ma ◽

Xiao-Zhi Tang ◽

Yong Mao ◽

Ya-Fang Guo

Keyword(s):

Molecular Dynamics ◽

Plastic Deformation ◽

Phase Transformation ◽

Molecular Dynamics Simulations ◽

Single Crystals ◽

Deformation Mechanisms ◽

Shear Stresses ◽

Affecting Factors ◽

Fcc Phase ◽

Dynamics Simulations

The deformation mechanisms of Mg, Zr, and Ti single crystals with different orientations are systematically studied by using molecular dynamics simulations. The affecting factors for the plasticity of hexagonal close-packed (hcp) metals are investigated. The results show that the basal <a> dislocation, prismatic <a> dislocation, and pyramidal <c + a> dislocation are activated in Mg, Zr, and Ti single crystals. The prior slip system is determined by the combined effect of the Schmid factor and the critical resolved shear stresses (CRSS). Twinning plays a crucial role during plastic deformation since basal and prismatic slips are limited. The 101¯2 twinning is popularly observed in Mg, Zr, and Ti due to its low CRSS. The 101¯1 twin appears in Mg and Ti, but not in Zr because of the high CRSS. The stress-induced hcp-fcc phase transformation occurs in Ti, which is achieved by successive glide of Shockley partial dislocations on basal planes. More types of plastic deformation mechanisms (including the cross-slip, double twins, and hcp-fcc phase transformation) are activated in Ti than in Mg and Zr. Multiple deformation mechanisms coordinate with each other, resulting in the higher strength and good ductility of Ti. The simulation results agree well with the related experimental observation.

Download Full-text

The Molecular dynamics simulations of the mechanical behavior of nanostructured and amorphous Al80Ti15Ni5 alloy

Revista Facultad de Ingeniería Universidad de Antioquia ◽

10.17533/udea.redin.20201009 ◽

2020 ◽

Author(s):

Alexandre Melhorance Barboza ◽

Ivan Napoleão Bastos ◽

Luis César Rodríguez Aliaga

Keyword(s):

Molecular Dynamics ◽

Mechanical Behavior ◽

Molecular Dynamics Simulations ◽

Atomic Structure ◽

Amorphous Material ◽

Young Modulus ◽

Grain Boundary Sliding ◽

Deformation Mechanisms ◽

Interatomic Potentials ◽

Dynamics Simulations

Classical deformation mechanisms based on crystalline defects of metallic polycrystals are not entirely suitable to describe the mechanical behavior of nanocrystalline and glassy materials. Their inherent complexity creates a real challenge to understand the acting physical phenomena. Thus, the molecular dynamics approach becomes interesting because it allows evaluating the mechanical properties and its related atomic structure. To study the atomic structure's influence on the deformation mechanisms at the nanoscale level of the Al80Ti15Ni5 alloy, molecular dynamics simulations, and post-processing techniques were used in the present work. The results revealed a significant dependency between the Young modulus and the atomic structure. Moreover, the type of structure, i.e., nanocrystalline or amorphous, governs the deformation mechanism type. For the nanocrystalline alloy, grain boundary sliding and diffusion seem to be the dominant deformation processes followed by the less essential emissions of partial dislocations from the grain boundaries. Concerning the amorphous material, the shear transformation zones begin to form in the elastic regime evolving to shear bands, these being the main mechanisms involved in the deformation process. The results also indicate the amorphous structure as a lower limit-case of the nanocrystal. The Al80Ti15Ni5 elastic moduli values were below expectations; for this reason, the effects of unary and ternary interatomic potentials were evaluated for each element.

Download Full-text