Article
Materials Science, Multidisciplinary
Wenqian Wu, Mingyu Gong, Bingqiang Wei, Amit Misra, Jian Wang
Summary: Al-Si cast alloys composed of alpha-Al and Al-Si eutectic often do not show significant improvement in mechanical properties due to Si flakes. The weak strengthening effect of Si flakes may be attributed to the low shear resistance and easy interaction of dislocations with Al-Si interfaces, leading to a decrease in the repulsive force on approaching dislocations and weakening the strengthening effect of Si flakes.
Article
Nanoscience & Nanotechnology
Wenqian Wu, Bingqiang Wei, Amit Misra, Jian Wang
Summary: Atomistic simulations reveal that dislocations nucleate at Al-Si interfaces and propagate in Al nano-channels, looping and bowing around Si nanofibers. Multiple active slip systems and dislocation cross-slips lead to high dislocation density, forming dislocation junctions and promoting the formation of dislocation forests. The plasticity of Si nanofibers is accommodated by local shears and fracture triggered by accumulated dislocation loops. Cracking of Si nanofibers can be buffered by dislocation mobility in the surrounding Al. These results are consistent with experimental observations.
SCRIPTA MATERIALIA
(2023)
Article
Engineering, Mechanical
Prottay Malakar, Md Al Rifat Anan, Mahmudul Islam, Md Shajedul Hoque Thakur, Satyajit Mojumder
Summary: This paper studied the fracture and deformation mechanisms of functionally graded and coreshell Silver-Gold (Ag-Au) nanospheres under compression load using molecular dynamics simulation. The results showed that plastic deformation was influenced by dislocation nucleation and propagation, which varied with the alloying percentages of the nanospheres. An inverse size effect was observed for the mechanical properties and deformation mechanism.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2022)
Article
Materials Science, Multidisciplinary
Z. Zhen, H. Wang, C. Y. Teng, C. G. Bai, D. S. Xu, R. Yang
Summary: In this study, super-dislocation dipoles in gamma-TiAl and alpha(2)-Ti3Al were systematically investigated by atomistic simulations, with the results showing their transformation under different annealing conditions and the influence on mechanical properties.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2021)
Article
Materials Science, Multidisciplinary
Matthew T. Curnan, Dongjae Shin, Wissam A. Saidi, Judith C. Yang, Jeong Woo Han
Summary: GB engineering plays a crucial role in optimizing catalysis and related materials phenomena by systematically classifying low-angle and high-angle grain boundaries and linking various properties through strain footprints. This research aims to evaluate the differences between low-angle and high-angle GBs, explain their origins, and connect transitions to materials phenomena. By utilizing a hierarchical statistical model and simplified strain footprints, this study successfully detects transitions and correlates them with catalytically relevant materials phenomena under a universal atomistic framework.
Article
Engineering, Mechanical
Dongpeng Hua, Qiaosheng Xia, Wan Wang, Qing Zhou, Shuo Li, Dan Qian, Junqin Shi, Haifeng Wang
Summary: Understanding contact-induced behavior in metals is crucial for studying mechanical properties. Nanoindentation studies on CoCrNi MEA revealed unique dislocation nucleation at Cr-rich clusters, contrary to conventional homogeneous nucleation in pure metals. Compositional inhomogeneity and temperature were found to influence defect behavior, with nanotwin formation and phase-transformation promoted at low temperatures.
INTERNATIONAL JOURNAL OF PLASTICITY
(2021)
Article
Materials Science, Multidisciplinary
Sergei Starikov, Vahid Jamebozorgi, Daria Smirnova, Ralf Drautz, Matous Mrovec
Summary: Screw and edge dislocations in body-centered cubic transition metals exhibit distinct diffusion characteristics, with the migration along screw dislocations being faster due to their different atomic structures.
Article
Chemistry, Physical
Lei Zhang, Gabor Csanyi, Erik van der Giessen, Francesco Maresca
Summary: Predicting atomistic fracture mechanisms in bcc iron is crucial for understanding its semi-brittle nature. By using a Gaussian approximation potential, we developed a model that accurately predicts critical stress intensity factors for different crack systems. Simulations revealed the mechanism of fracture along the original crack plane for {100} and {110} crack planes.
NPJ COMPUTATIONAL MATERIALS
(2023)
Article
Engineering, Mechanical
Le Chang, Takayuki Kitamura, Chang-Yu Zhou, Xiao-Hua He
Summary: The comparison between 2D and 3D atomistic simulations of anisotropic crack tip response in hcp titanium shows significant differences in near tip stress fields, incipient crack tip deformation, and critical stress intensity factor. Crack tip plasticity is predominantly contributed by the inclined slip mode in 2D simulations, while the lower stress triaxiality in 3D simulations leads to easier dislocation nucleation. The behaviors observed in 3D simulations are more consistent with experimental results.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2021)
Article
Materials Science, Multidisciplinary
Ping Yu, Guisen Liu, Kaitao Wu, Yanguang Cui, Guannan Zhao, Yao Shen
Summary: Understanding the interaction mechanisms between dislocations and irradiation-induced nanosized voids is critical for predicting the performance of nuclear components. Previous research mostly focused on the first interaction, assuming that already sheared voids have the same hardening effects. Using atomistic simulations, this work studies the interaction mechanisms and corresponding hardening effects between a periodic array of voids and successively incoming dislocations.
JOURNAL OF NUCLEAR MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Angelina Kh. Akhunova, Leysan Kh. Galiakhmetova, Julia A. A. Baimova
Summary: This research paper investigates the fracture and mechanical properties of rippled graphene containing dislocation dipoles. Atomistic simulation is used to analyze the deformation behavior of pristine and defective wrinkled graphene. The results show that graphene wrinkling reduces the ultimate tensile strength of both pristine and defective graphene, but increases the fracture strain. The mechanical properties of graphene with dislocation dipoles are less affected by temperature compared to graphene and graphene with Stone-Wales defect. Moreover, defects in graphene can also influence its wrinkling, potentially hindering wrinkle formation.
APPLIED SCIENCES-BASEL
(2023)
Article
Nanoscience & Nanotechnology
Yang Su, Thanh Phan, Liming Xiong, Josh Kacher
Summary: This paper combines in situ high-resolution electron backscattered diffraction (EBSD) with concurrent atomistic-continuum (CAC) simulations to investigate the interactions between dislocation-mediated slip and grain boundaries (GBs) in Ni. The study shows that the local stress at slip-GB intersections initially increases with the pileup of dislocations and remains high, even after the nucleation of dislocations in the neighboring grain. The local stress only relaxes when the nucleated dislocations propagate away from the GB due to more incoming dislocations participating in the pileup. The relaxation of local stress is accompanied by the reconfiguration of atomic-scale GB structure, which not only affects subsequent dislocation transmission but also the configuration of dislocations away from the GB. These findings highlight the importance of incorporating local stress history in higher length scale models, such as crystal plasticity finite element.
SCRIPTA MATERIALIA
(2023)
Article
Chemistry, Physical
Shan Liu, Yao Lin, Tao Wu, Guangchun Wang
Summary: By simulating torsion deformation, it was found that the grains in Ni50.8Ti wires rotated and elongated, forming long strips of grains. With increasing torsion deformation, the elongated grains further split into smaller grains. The generation of dislocations and stress-induced martensitic transformation also occurred. The main mechanism of plastic deformation varied with different degrees of torsion deformation.
Article
Engineering, Mechanical
Yongpan Zeng, Xiaoyan Li
Summary: This study conducted large-scale atomistic simulations to investigate the high-temperature creep mechanisms of nanocrystalline and nanotwinned TiAl alloys, revealing the influences of applied stress, grain size, and temperature on creep behaviors and mechanisms. Particularly, a critical twin thickness was identified for nanotwinned samples under high stress, leading to a transition in creep mechanism from dislocation nucleation and slip to detwinning.
EXTREME MECHANICS LETTERS
(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
Materials Science, Multidisciplinary
Nizar Lefi, Salem Neily, Roland Bonnet
Summary: This paper investigates the elastic field in a bi-material crystal with an angular dislocation line with one branch placed in the crystal and the other along a strongly bound or welded interface. The analysis formulates the elastic field of a closed dislocation loop and solves it using the knowledge of the Green's tensor of the bi-material. The study provides a faster calculation method and has important implications for solving interfacial angular dislocation problems.
PHILOSOPHICAL MAGAZINE
(2024)
