Article
Materials Science, Multidisciplinary
Nikhil Chandra Admal, Tusher Ahmed, Enrique Martinez, Giacomo Po
Summary: The CSL/DSCL model provides a unified framework to study interface dislocations in crystalline materials, but its applicability to arbitrary rational boundaries is limited. This paper presents a mathematical framework based on integer matrices to study the bicrystallography of rational phase and grain boundaries. The results show the invariance of the coincident site lattice (CSL) under discrete relative displacements and provide necessary conditions for the existence of a coincidence relation. The framework can be used to explore coincidence relations in phase boundaries and enumerate disconnection modes in grain boundaries.
Article
Materials Science, Multidisciplinary
Himanshu Joshi, Junyan He, Nikhil Chandra Admal
Summary: Grain boundary processes such as shear coupling and sliding are consequences of plastic distortion during grain boundary motion. This study introduces the concept of disconnections as the primary carriers of grain boundary plasticity, and develops a diffuse-interface finite deformation theory for grain boundary plasticity based on the notion of geometrically necessary disconnections. The proposed model can accurately describe phenomena such as state-dependent shear coupling, mode switching, grain boundary sliding, and grain rotation.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2022)
Article
Materials Science, Multidisciplinary
Caihao Qiu, Marco Salvalaglio, David J. Srolovitz, Jian Han
Summary: An intrinsic feature of crystalline systems is the presence of disconnections, which strongly affect the morphology and motion of interfaces. These elastic interactions modify equilibrium interface morphologies compared to surface energy and affect interface kinetics, leading to a faceting-defaceting transition.
Article
Materials Science, Multidisciplinary
Bin Li, Janel Leung
Summary: The migration of symmetric tilt grain boundaries (GBs) in face centered cubic copper under a shear strain at 100 K was studied. Results showed that the angles between specific atomic planes could determine the mode of motion of the GB, whether it is by shear coupling, hybrid mode of shear coupling + sliding, or only GB sliding. Structural analyses revealed atomic planes behavior during shear coupling, allowing the identification of transformation units and rate-limiting factors for lattice transformation.
Article
Nanoscience & Nanotechnology
Maximilian Kern, Michael Bernhard, Christian Bernhard, Youn-Bae Kang
Summary: The grain boundary migration of pure electrolytic iron (Fe > 99.98%) was investigated at different temperatures using high-temperature laser scanning confocal microscopy. A mathematical model considering the dependence of grain size on time and temperature was used to determine the grain boundary mobility. The obtained mobility values were significantly different from Turnbull's postulation and matched published data on austenite grain growth in multicomponent steels.
SCRIPTA MATERIALIA
(2023)
Article
Materials Science, Multidisciplinary
Zhengwu Fang, Boyang Li, Susheng Tan, Scott Mao, Guofeng Wang
Summary: This study reveals the atomic-scale migration behavior of a typical shear-coupled mixed tilt-twist GB (MGB) in Au nanocrystals. Two distinct migration patterns were observed, mediated by GB disconnections with different crystallographic parameters. The study also found that excess GB sliding and GB plane reorientation accommodate the GB migration. These findings provide valuable insights into optimizing the ductility of metallic nanocrystals through controlling GB migration.
Article
Materials Science, Multidisciplinary
Gashaw B. Bizana, Luis A. Barrales-Mora
Summary: Classical theories assume a linear correlation between grain boundary curvature and velocity, but recent experimental observations suggest a more complex relationship in polycrystalline materials. Molecular dynamics simulations of nanosized polycrystalline Al annealing were used to determine the velocity and curvature of approximately 12,000 grain boundaries. The study revealed differences in kinetics behavior at the grain and grain-boundary levels, with a clear correlation between grain boundary curvature and migration direction. However, when considering all grain boundaries, the correlation between velocity and curvature was found to be low, indicating the complexity of grain boundary migration. Factors such as grain boundary character, defect distributions, and stress distribution between neighboring grains were found to influence grain boundary migration behavior.
Article
Nanoscience & Nanotechnology
Megan J. McCarthy, Timothy J. Rupert
Summary: This study investigates the migration behavior of a faceted Sigma 11 boundary in Cu doped with Ag atoms, revealing that solute atoms segregate to a facet with more free volume and greatly reduce boundary velocity in one migration direction. However, a directionally-dependent motion mechanism can escape solute pinning and speed up migration in the other direction, uncovering a new mechanism of chemically-induced anisotropy in grain boundary mobility.
SCRIPTA MATERIALIA
(2021)
Article
Chemistry, Physical
Masoud Ghasemi, Boyu Guo, Kasra Darabi, Tonghui Wang, Kai Wang, Chiung-Wei Huang, Benjamin M. Lefler, Laine Taussig, Mihirsinh Chauhan, Garrett Baucom, Taesoo Kim, Enrique D. Gomez, Joanna M. Atkin, Shashank Priya, Aram Amassian
Summary: This study reveals a multiscale diffusion mechanism of vacancy-mediated halide diffusion in metal halide perovskites, showing an inverse relationship between grain boundary diffusion and volume diffusion. Stable metal halide perovskites have larger grain boundary diffusivities and smaller volume diffusivities, reducing hysteresis.
Article
Materials Science, Multidisciplinary
J. Zimmerman, A. Aviv, Y. Elfassy, A. Bisht, L. Klinger, E. Rabkin
Summary: The effect of surface topography on grain boundary migration in thin films has been investigated in this study. In pure bulk Ni samples, large protrusions resembling downscaled terrestrial mountains were observed near grain boundaries after mild cold deformation and subsequent annealing. These protrusions, called 'thermal ridges', decrease in size with increasing annealing time and degree of deformation. A kinetic model of ridges based on the modified Mullins' model was developed to explain this phenomenon. The combination of experimental and modeling results provides new insights into the formation of hillocks in thin polycrystalline films.
Article
Materials Science, Multidisciplinary
Chongze Hu, Stephane Berbenni, Douglas L. Medlin, Remi Dingreville
Summary: Twinning is a common deformation mechanism in nanocrystalline metals, and solute segregation at twin boundaries plays a vital role in their stability and strengthening. This study reveals a possible discontinuity of solute segregation patterns across a disconnection defect in a wide range of binary alloys. The change in segregation pattern is attributed to the break of local symmetry caused by the disconnection terraces. These findings enhance our understanding of interface segregation phenomena and emphasize the importance of interfacial defects in alloy design.
Article
Materials Science, Multidisciplinary
Robert D. Moore, Timothy Beecroft, Gregory S. Rohrer, Christopher M. Barr, Eric R. Homer, Khalid Hattar, Brad L. Boyce, Fadi Abdeljawad
Summary: GB stiffness in Ni can be larger and more anisotropic than energy, with some boundary inclinations exhibiting negative stiffness. Results from this study are qualitatively consistent with experimental observations, providing new avenues for examining the plane normal dependency of GB properties in mesoscale treatments of GB migration and microstructural evolution.
Article
Nanoscience & Nanotechnology
Fusheng Tan, Jia Li, Hui Feng, Qihong Fang, Chao Jiang, Yong Liu, Peter K. Liaw
Summary: This study investigates the nanoscale grain boundary structure and migration mechanism in multi-principal element alloys, revealing the roughening transformation of grain boundaries as mixing entropy increases. It confirms the effect of entropy on grain boundary migration, showcasing different migration mechanisms for ordered and disordered grain boundaries under different entropy conditions.
SCRIPTA MATERIALIA
(2021)
Review
Materials Science, Multidisciplinary
Gregory S. Rohrer, Ian Chesser, Amanda R. Krause, S. Kiana Naghibzadeh, Zipeng Xu, Kaushik Dayal, Elizabeth A. Holm
Summary: Grain boundaries in polycrystalline materials migrate to reduce excess energy. Previous studies found that the migration rates of boundaries in bicrystals are insufficient to explain boundary migration in polycrystals. In this review, we discuss the atomistic mechanisms of grain boundary migration based on simulations and microscopy observations. We also explore the continuum scale understanding of grain boundary migration through simulations and observations. It is concluded that detailed comparisons between experiments and atomistic simulations in polycrystals are necessary to better understand the migration mechanisms, and that current simulations of grain growth are inadequate in reproducing experimental observations.
ANNUAL REVIEW OF MATERIALS RESEARCH
(2023)
Article
Materials Science, Multidisciplinary
Ting Luo, Dominique Mangelinck, Federico Serrano-Sanchez, Chenguang Fu, Claudia Felser, Baptiste Gault
Summary: Pt-doped NbCoSn is a promising compound for thermoelectric applications. Grain boundary segregation of Pt dopants and an anti-correlation between species are observed near the grain boundaries. These findings are valuable for the design of thermoelectric materials with optimal conversion efficiency.
Article
Materials Science, Multidisciplinary
Marco Salvalaglio, David J. Srolovitz, Jian Han
Summary: The motion of interfaces plays a crucial role in the microstructure evolution of crystalline materials. This study presents a microstructure evolution simulation approach that is linked to the underlying microscopic mechanisms of interface migration. The method extends the continuum approach to a diffuse interface, phase-field model, allowing for large-scale simulations. The results highlight the influence of microscopic interface migration mechanisms on microstructure evolution, particularly the effects of stress and its coupling to interface migration.
Article
Multidisciplinary Sciences
Lihua Wang, Yin Zhang, Zhi Zeng, Hao Zhou, Jian He, Pan Liu, Mingwei Chen, Jian Han, David J. Srolovitz, Jiao Teng, Yizhong Guo, Guo Yang, Deli Kong, En Ma, Yongli Hu, Baocai Yin, XiaoXu Huang, Ze Zhang, Ting Zhu, Xiaodong Han
Summary: Grain boundaries (GBs) are crucial for the mechanical behavior of polycrystalline materials, yet the atomic-scale dynamic processes of GB deformation remain unclear. This study presents an in situ atomic-resolution investigation on how sliding-dominant deformation occurs at general tilt GBs in platinum bicrystals, involving direct atomic-scale sliding and sliding with atom transfer across the boundary plane.
Article
Multidisciplinary Sciences
A. S. L. Subrahmanyam Pattamatta, David J. Srolovitz
Summary: In this study, a crystal thermodynamics framework is proposed to describe phase transformations induced by tensor stress in solids. The approach is based on nonlinear elasticity and first principles calculations. It allows for the prediction of phase transformations in grains of any orientation in different materials, regardless of the effects from the stress tensor.
NATURE COMMUNICATIONS
(2022)
Article
Materials Science, Multidisciplinary
Mingjie Xu, Kongtao Chen, Fan Cao, Leonardo Velasco, Thomas M. Kaufman, Fan Ye, Horst Hahn, Jian Han, David J. Srolovitz, Xiaoqing Pan
Summary: This study presents the mechanism of grain boundary motion in polycrystalline materials through novel observations, simulations, and disconnection theory. The results show that the motion of grain boundaries is coupled through disconnection motion/reactions at grain boundary triple junctions. The driving force for migration affects the mode selection, with different modes observed under chemical potential jump and stress-driven conditions.
Article
Materials Science, Multidisciplinary
Larissa M. Woryk, Sicong He, Emily M. Hopkins, Chang-Yu Hung, Jian Han, David J. Srolovitz, Jaime Marian, Mitra L. Taheri
Summary: A numerical methodology is presented to compute the Nye-tensor fingerprints of dislocation loop absorption at grain boundaries (GBs) and compare them with TEM observations. This approach connects atomistic simulations with experimentally extracted GND maps to facilitate the interpretation of damage processes. The method provides a framework for future investigations of defect absorption by grain boundaries under irradiation conditions.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Rui Wang, Xiaoxiao Ma, Linfeng Zhang, Han Wang, David J. Srolovitz, Tongqi Wen, Zhaoxuan Wu
Summary: This study focuses on the development of two interatomic potentials for BCC vanadium (V) using classical semiempirical modified embedded-atom method and the ML Deep Potential framework. Both potentials can reproduce various defect properties relevant to plastic deformation and fracture.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Caihao Qiu, Marco Salvalaglio, David J. Srolovitz, Jian Han
Summary: An intrinsic feature of crystalline systems is the presence of disconnections, which strongly affect the morphology and motion of interfaces. These elastic interactions modify equilibrium interface morphologies compared to surface energy and affect interface kinetics, leading to a faceting-defaceting transition.
Article
Materials Science, Multidisciplinary
W. Streit Cunningham, Yang Zhang, Spencer L. Thomas, Osman El-Atwani, Yongqiang Wang, Jason R. Trelewicz
Summary: Formation of helium cavities in coarse-grained materials leads to hardening, while preferential cavity formation in grain boundaries in nanostructured metals causes softening. This study uses ultrafine-grained tungsten to investigate the effect of cavity evolution on mechanical response. Softening is observed at high implantation temperatures but low fluence, accompanied by cavity coalescence and reduction in hardness. Atomistic simulations reveal that softening is driven by stress concentrations and cooperative deformation processes in grain boundaries.
Article
Materials Science, Multidisciplinary
Shuai Chen, Zachary H. Aitken, Subrahmanyam Pattamatta, Zhaoxuan Wu, Zhi Gen Yu, David J. Srolovitz, Peter K. Liaw, Yong-Wei Zhang
Summary: By employing density-functional theory calculations, Monte Carlo method, and molecular dynamic simulation, this study investigates the role of short-range ordering (SRO) on dislocation kinetics in a BCC MoTaTiWZr high-entropy alloy. The results demonstrate that SRO enhances the energy barriers for both edge and screw dislocation motion, giving rise to the dominance of edge dislocations in the BCC RHEA.
Article
Engineering, Mechanical
Tongqi Wen, Anwen Liu, Rui Wang, Linfeng Zhang, Jian Han, Han Wang, David J. Srolovitz, Zhaoxuan Wu
Summary: This study determines the properties of dislocation cores, twins, and cracks in HCP and BCC Ti using Deep Potential (DP), DFT, and linear elastic fracture mechanics. It provides insights into the behavior of slip dislocations and the brittleness of cracks on basal planes, as well as the energy and structure of twin boundaries. The results offer a comprehensive understanding of Ti plasticity and fracture.
INTERNATIONAL JOURNAL OF PLASTICITY
(2023)
Article
Multidisciplinary Sciences
Shuai Chen, Ping Liu, Qingxiang Pei, Zhi Gen Yu, Zachary H. Aitken, Wanghui Li, Zhaoxuan Wu, Rajarshi Banerjee, David J. Srolovitz, Peter K. Liaw, Yong-Wei Zhang
Summary: This study constructs nanolamellar high-entropy alloys and explores their mechanical properties using molecular dynamic simulation and density functional theory calculation. The results show that the nanolamellar structure exhibits ideal plastic behavior and remarkable shape memory effect, highlighting the importance of nanolamellar structures in controlling the mechanical and functional properties of high-entropy alloys.
