Article
Materials Science, Multidisciplinary
J. D. Gravell, S. Lee, S. Ryu, I Ryu
Summary: At micron and nanometer length scales, metals exhibit strong anisotropic behaviors. Three-dimensional dislocation dynamics simulations can be used to investigate the plasticity and microstructure evolution in metal micropillars of different orientations.
Article
Materials Science, Multidisciplinary
Yinan Cui, Nasr Ghoniem, Giacomo Po
Summary: This study reviewed recent work on plastic deformation in irradiated materials at the nano- and micro scales using Discrete Dislocation Dynamics (DDD) simulations. The simulations provided new insights into collective dislocation-irradiation defect interactions, as well as the temporal and spatial characteristics associated with plastic instabilities. The development of theoretical models and probability models advanced the understanding of plastic flow localization in irradiated materials for the design of future radiation-resistant materials.
JOURNAL OF NUCLEAR MATERIALS
(2021)
Article
Nanoscience & Nanotechnology
F. J. Dominguez-Gutierrez, S. Papanikolaou, A. Esfandiarpour, P. Sobkowicz, M. Alava
Summary: The study investigates the effects of high temperature on the mechanical deformation properties of single crystalline Mo under nanoindentation, revealing that temperature increase changes dislocation densities, mechanisms, atomic displacements, and hardness. The characteristic formation of [001] dislocation junctions and high-temperature stability may be responsible for the persistent thermomechanical stability of Mo, contrasting with other BCC metals.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Nanoscience & Nanotechnology
Ryan B. Sills, Michael E. Foster, Xiaowang Zhou
Summary: The character angle dependence of dislocation-solute interactions in a random Fe0.70Ni0.11Cr0.19 alloy was explored through molecular dynamics simulations, showing that the activation area in this alloy is governed by dislocation line tension rather than the dislocation-solute interaction itself. This finding motivates further research into the line geometry of dislocations in solid solutions.
SCRIPTA MATERIALIA
(2022)
Article
Physics, Fluids & Plasmas
Pavel Sasorov, Arkady Vilenkin, Naftali R. Smith
Summary: The Brownian bees model describes a collection of N independent branching Brownian particles. The density of the particles is governed by a reaction-diffusion equation. The particle density approaches a symmetric steady-state solution at long times, but fluctuates at finite N values.
Article
Materials Science, Multidisciplinary
Nicole K. Aragon, Jamie D. Gravell, Ill Ryu
Summary: Research demonstrates that grain boundaries play a crucial role in nanostructured metals, influencing plastic deformation by controlling dislocation propagation. Different samples with high angle grain boundaries and coherent twin boundaries show distinct mechanical responses in plastic deformation.
Article
Materials Science, Multidisciplinary
Tawqeer Nasir Tak, Aditya Prakash, Shyam M. Keralavarma, Indradev Samajdar, P. J. Guruprasad
Summary: This study extended a single crystal dislocation creep model into polycrystalline ensemble, and simulated the mechanical behavior of polycrystalline aluminum. The results showed the relationship between strain rate and temperature, stress, and grain size, and revealed the controlling mechanism of dislocation interactions with static obstacles and grain boundaries.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2023)
Article
Physics, Multidisciplinary
Zhitao Chen, Duanduan Wan, Mark J. Bowick
Summary: Even at zero temperature, very thin elastic sheets exhibit nonlinear elastic response. Molecular dynamics simulations reveal a tilted phase where the sheet fluctuates about a mean configuration inclined with respect to the horizontal. A model is developed to predict the tilted and untilted regions in the phase diagram. These findings have significant implications for two-dimensional mechanical metamaterials.
PHYSICAL REVIEW LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Yejun Gu, Zhi Li, Huajian Gao
Summary: In this study, a series of discrete dislocation dynamics (DDD) simulations were performed to confirm the existence of hetero-boundary-affected regions (HBARs) and investigate their formation, growth, and evolution mechanisms during plastic deformation. The simulations revealed that HBARs have a heterogeneous dislocation microstructure with distinct stress/strain gradients, which depend on the penetrability of interfaces and the applied strain. Furthermore, it was shown that HBARs significantly impact the mechanical responses of materials. This study provides a mechanistic basis for understanding the formation mechanism of HBARs, which is crucial for physics-based modeling of the mechanical behavior of heterostructured materials.
Article
Engineering, Mechanical
Songjiang Lu, Qianhua Kan, Michael Zaiser, Zhenhuan Li, Guozheng Kang, Xu Zhang
Summary: This study examines the effects of grain size and dislocation source properties on the yield stress of ultrafine-grained polycrystals using three-dimensional multiscale discrete dislocation dynamics. The simulation demonstrates a nonmonotonic dependency of flow stress on dislocation source length and deviations from the classical Hall-Petch relationship in the grain size dependence of yield stress. The study provides insights into the controlling factors of yield stress in the ultrafine-grained regime and proposes a theoretical model to explain the combined effects of source length, grain size, and initial dislocation density.
INTERNATIONAL JOURNAL OF PLASTICITY
(2022)
Article
Nanoscience & Nanotechnology
Sho Hayakawa, Haixuan Xu
Summary: In this study, we investigate the interaction between a dislocation and nanotwin-hexagonal close-packed (hcp) lamella in Ni-based concentrated alloys using molecular dynamics simulations. We identify two types of interaction modes with different contributions to the ductility. The dominant mode and critical stress dependences could lead to the simultaneous increase in the strength and ductility with decreasing temperature in NiCoCr. Additionally, the type of interaction mode is influenced by the hcp lamella thickness, which can further enhance the ductility.
SCRIPTA MATERIALIA
(2022)
Article
Materials Science, Multidisciplinary
J. Zimmerman, A. Bisht, Y. Mishin, E. Rabkin
Summary: The compressive strength of Pt nanoparticles shows a size effect, with smaller particles achieving the highest strength, and the particle shape (expressed by the ratio of top facet to projected diameter) also affects strength. The results suggest that Pt nanoparticles have lower strength normalized by shear modulus compared to other face-centered cubic metals.
JOURNAL OF MATERIALS SCIENCE
(2021)
Article
Chemistry, Physical
Jiaqing Li, Ziyue Wu, Lin Teng, Guanyu Deng, Rui Wang, Cheng Lu, Weidong Li, Xin Huang, Yu Liu
Summary: Molecular dynamics simulations were used to study the effects of hydrogen segregation on dislocation plasticity in symmetrical tilt grain boundaries with different hydrogen concentrations. The results showed that hydrogen can both enhance and reduce dislocation formation, depending on the structure of the grain boundary.
Article
Materials Science, Multidisciplinary
N. Combe, F. Mompiou, M. Legros
Summary: In this study, a systematic investigation of coupling modes in grain boundary migration was conducted with molecular dynamics simulations. Multiple coupling modes and associated disconnections were identified, indicating that grain boundary migration may occur through the successive occurrence of two modes.
Article
Physics, Multidisciplinary
Yang Xiang, Yuying Yu, Yinan Cui, Jianbo Hu
Summary: This study investigates the dynamic yield behavior of single-crystal tungsten using discrete dislocation dynamics (DDD) and finds that the initial dislocation source length and density affect the initial yield and flow stress of tungsten. With increasing dislocation density and length, the plastic yield mechanism shifts from dislocation source activation to dislocation-dislocation interactions, resulting in a decrease in initial yield stress and an increase in flow stress.