Article
Materials Science, Multidisciplinary
N. Kvashin, A. Ostapovets, N. Anento, A. Serra
Summary: Tilt grain boundaries move conservatively under shear stress by absorbing crystal dislocations and transforming them into grain boundary dislocations (GBD). The behavior of GBDs depends on the orientation of the Burgers vector and shear stress direction, resulting in either compensated climb or nucleation of {1 1 2} twins.
COMPUTATIONAL MATERIALS SCIENCE
(2021)
Article
Chemistry, Physical
Shufen Chu, Junnan Jiang, Xiaoran Zhao, Baode Sun, Pan Liu
Summary: This study reveals the coupled dislocation climb and glide in nanoporous gold ligaments with low-angle grain boundaries, providing insights into the deformation of nanoporous metals and implications for grain boundary engineering at room temperature.
Article
Chemistry, Physical
Shufen Chu, Junnan Jiang, Xiaoran Zhao, Baode Sun, Pan Liu
Summary: In this study, atomic scale visualizations of low-angle grain boundaries in nanoporous metal ligaments were conducted through in situ tensile straining inside a transmission electron microscope. The simultaneous climb and glide of grain boundary dislocations were observed and the motion paths of dislocation cores were precisely determined by real-time tracking.
Article
Chemistry, Physical
Vasiliy Krasnikov, Alexander Mayer, Polina Bezborodova, Marat Gazizov
Summary: This paper investigates the impact of Cu atom concentration at grain boundaries (GBs) on plastic relaxation mechanisms and mechanical response in nanocrystalline aluminum using molecular dynamics simulations. The study reveals a nonmonotonic relationship between the critical resolved shear stress and Cu content at GBs, which is attributed to changes in plastic relaxation mechanisms. At low Cu content, GBs slip via dislocation walls, whereas an increase in Cu content leads to dislocation emission from GBs and grain rotation with GB sliding.
Article
Materials Science, Multidisciplinary
Kai Hu, Jun Yi, Bo Huang, Xilei Bian, Gang Wang
Summary: This study overcomes the trade-off between strength and ductility in pure nickel materials by using grain boundary relaxation and optimizing grain size. The results show that grain boundary relaxation can improve both tensile strength and uniform elongation of nickel, and enhance the plastic deformation through controlling dislocation activities.
APPLIED MATERIALS TODAY
(2022)
Article
Chemistry, Physical
A. Hassani, A. Khmich, A. Hasnaoui
Summary: Molecular dynamics simulations were used to investigate the structure of mismatched Al/Ni and Ag/Cu interfaces on low-index substrate surfaces. Embedded Atom Potentials were employed to mimic atomic interactions. The effect of substrate orientation on the adlayer structure was studied. Results showed that the adlayer on the (1 1 1) substrate exhibited a coincidence site lattice with a rotation (alpha) relative to the substrate, potentially containing dislocations and twin boundaries. Deposition of the adlayer on the substrate led to slight atom shuffling and dislocations in the substrate, producing rectangular structures. On the (001) substrate, the accommodation of a triangular structure on a square lattice (substrate) resulted in a shift of atomic rows and the formation of dislocations, with multiple square structures agglomerating to form a polycrystal with grain boundaries and vacancies. However, inward adsorption on the (1 1 0) substrate limited the extension of adsorbed atoms, resulting in linear cracks. Relaxation of atoms adsorbed on these cracks led to a change in vacancy shape from linear to staircase.
APPLIED SURFACE SCIENCE
(2023)
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
Chemistry, Physical
Jaber Rezaei Mianroodi, Pratheek Shanthraj, Bob Svendsen, Dierk Raabe
Summary: The current work utilizes Microscopic Phase-Field Chemomechanics to model solute segregation, dislocation-solute interaction, spinodal decomposition, and precipitate formation at straight dislocations and boundaries, exploring the effects of different configurations.
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
Materials Science, Multidisciplinary
Zhifu Zhao, Babak Safaei, Yanfei Wang, Fulei Chu, Yueguang Wei
Summary: This study investigated grain boundary elimination in two special bcc iron bicrystals through molecular dynamics simulations. The results showed that the elimination of grain boundaries enhanced resistance to intergranular fracture and led to directional anisotropy of intergranular crack propagation. The mechanisms of grain boundary elimination were revealed to be twinning and dislocation activities. This research provides valuable insights for grain boundary design.
MATERIALS & DESIGN
(2022)
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
Materials Science, Multidisciplinary
Shipeng Wang, Xiaohui Cui, Ang Xiao, Lei Zhang, Peng Zhao
Summary: This study investigates the effect of induced electro-pulsing treatment (IEPT) on the microstructure evolution and mechanical properties of pre-stretched 5052-O aluminum alloy. The results show that the application of induced current significantly reduces the yield strength and increases the elongation of pre-stretched specimens. The microstructural analysis reveals more uniformly distributed dimples, increased grain size and number of low angle grain boundaries, and changes in texture types after the induced current application.
METALS AND MATERIALS INTERNATIONAL
(2023)
Article
Chemistry, Physical
Xixi Qi, Yangxin Li, Xiaoqin Zeng
Summary: This study investigates the impact of activating and accumulating prismatic < a > dislocations on the ductility of a Mg-7.37Gd-3.1Y-0.27Zr (GW83K) alloy at sub-zero temperatures. It is observed that prismatic < a > dislocations are more easily activated at lower temperatures due to a decrease in the ratio of CRSS prismatic < a > to CRSS basal < a > in this alloy. Increasing the proportion of prismatic < a > dislocations has limited effect on improving the early-stage deformation ductility of GW83K alloy at sub-zero temperatures, as the prismatic < a > dislocations cannot accommodate c-axis deformation. However, the accumulation of prismatic < a > dislocations leads to the formation of low-angle grain boundaries rotating along the [0001] axis, resulting in improved ductility in the late-stage deformation of GW83K alloy. This finding offers a new perspective on the contribution of prismatic < a > dislocations to ductility in Mg alloys.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Materials Science, Multidisciplinary
Wei Wan, Changxin Tang
Summary: In this atomistic study, the structure-property correlations of Si (001) small angle mixed grain boundaries (SAMGBs) were investigated. It was found that the energy trends of SAMGBs followed the revised Read-Shockley relationship, and the structural transitions were determined by the dislocation core radii. The proportion, topology and structural signatures of different SAMGB types were also examined.
Article
Materials Science, Multidisciplinary
Yin Zhang, Kunqing Ding, Sandra Stangebye, Dengke Chen, Josh Kacher, Olivier Pierron, Ting Zhu
Summary: Dislocation nucleation plays a crucial role in the plastic deformation of crystalline materials. However, accurately predicting the mode and rate of dislocation nucleation under typical experimental loading conditions through molecular dynamics simulation is challenging due to timescale limitations. In this study, the researchers used the free-end nudged elastic band method to determine the activation energies and activation volumes of dislocation nucleation in four typical face-centered cubic metals. Their focus was on surface and grain boundary dislocation nucleation processes. The atomistically determined activation volumes of these processes were found to be larger than 10b(3) under typical experimental loading conditions. The results were then compared with experimentally measured activation volumes in ultrafine-grained and nanocrystalline metals, providing mechanistic insight into their rate-controlling deformation mechanisms.
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
Engineering, Mechanical
Xuan Liang, Lisha White, Jonathan Cagan, Anthony D. Rollett, Yongjie Jessica Zhang
Summary: This study focuses on the structural design and additive manufacturing of cross-flow heat exchangers. A unit-based design framework is proposed to optimize the channel configuration for improved heat exchange performance and controlled pressure drop. Shape and topology changes are observed during the design process, and printability evaluation is considered for the metal laser powder bed fusion process.
JOURNAL OF MECHANICAL DESIGN
(2023)
Article
Engineering, Industrial
Sneha P. Narra, Anthony D. Rollett, Austin Ngo, David Scannapieco, Mahya Shahabi, Tharun Reddy, Joseph Pauza, Hunter Taylor, Christian Gobert, Evan Diewald, Florian X. Dugast, Albert To, Ryan Wicker, Jack Beuth, John J. Lewandowski
Summary: This manuscript provides a compact overview of the results that demonstrate the applicability of processing-structure-property relationships in 3D printing of metals. The proposed process qualification approach based on physics-based understanding of defect formation shows promise in enabling certification for aerospace-grade titanium alloy. It is expected to be applicable to other materials and powder bed fusion AM technologies.
JOURNAL OF MATERIALS PROCESSING TECHNOLOGY
(2023)
Article
Materials Science, Multidisciplinary
Runbo Jiang, Zhongshu Ren, Joseph Aroh, Amir Mostafaei, Benjamin Gould, Tao Sun, Anthony D. Rollett
Summary: The competition between epitaxial and equiaxed solidification was investigated in CMSX-4 single crystal superalloy during laser melting in additive manufacturing. Single-track laser scans were performed on a powder-free surface of directionally solidified CMSX-4 alloy with various laser power and scanning velocity combinations. The results showed that the as-solidified microstructure was dominated by epitaxial grain growth with the presence of stray grains in elongated melt pools. Higher laser scanning velocity and lower power were found to help reduce the occurrence of stray grains, and a stable keyhole and minimal fluid velocity further mitigated stray grains in laser single tracks.
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
(2023)
Article
Multidisciplinary Sciences
Zhongshu Ren, Lin Gao, Samuel J. Clark, Kamel Fezzaa, Pavel Shevchenko, Ann Choi, Wes Everhart, Anthony D. Rollett, Lianyi Chen, Tao Sun
Summary: Porosity defects in laser-based metal additive manufacturing could be a major obstacle. Researchers used synchrotron x-ray imaging and thermal imaging to study the phenomenon and developed a machine learning approach for detecting and predicting the generation of porosity. With the help of operando x-ray imaging, the approach can be adopted in commercial systems.
Article
Nanoscience & Nanotechnology
Hossein Beladi, Vahid Tari, Anthony D. Rollett, Gregory S. Rohrer
Summary: The current study reveals that the development of gamma-fibre texture in IF steel through static recrystallization alters the distribution of grain boundary misorientations and plane orientations. As the intensity of the gamma-fibre texture increases, there is a shift in the maximum grain boundary plane distribution and an increase in low angle boundary population.
SCRIPTA MATERIALIA
(2023)
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
Mohammadreza Asherloo, Junghyun Hwang, Ryan Leroux, Ziheng Wu, Kamel Fezzaa, Muktesh Paliwal, Anthony D. Rollett, Amir Mostafaei
Summary: Powder feedstock is a significant cost driver in metal additive manufacturing. Replacing spherical powder with cost-efficient non-spherical powder can reduce feedstock cost by up to 50% and increase interest in adopting additive manufacturing for production and new alloy development. A comprehensive study was conducted on the laser powder bed fusion of hydride-dehydride Ti-6Al-4V powder to understand the relationships between process, microstructure, and properties.
MATERIALS CHARACTERIZATION
(2023)
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, Manufacturing
Tracey Ziev, Erfan Rasouli, Ines-Noelly Tano, Ziheng Wu, Srujana Rao Yarasi, Nicholas Lamprinakos, Junwon Seo, Vinod Narayanan, Anthony D. Rollett, Parth Vaishnav
Summary: Advances in manufacturing technologies and materials are crucial to the commercial deployment of energy technologies. We present a cost-effective method for fabricating heat exchangers using additive manufacturing, specifically laser powder bed fusion, in the context of concentrating solar power with molten salt thermal storage.
3D PRINTING AND ADDITIVE MANUFACTURING
(2023)
Article
Multidisciplinary Sciences
Guannan Tang, Benjamin J. Gould, Anthony D. Rollett
Summary: Hot cracking is a major concern in metal alloy manufacturing process, causing detrimental effects and potential catastrophic failure. However, research in this field is limited by the scarcity of relevant hot cracking susceptibility data. In this study, the DXR technique provided at the 32-ID-B beamline of the Advanced Photon Source (APS) was used to characterize hot cracking formation in Laser Powder Bed Fusion (L-PBF) process for ten commercial alloys. The extracted DXR images captured the post-solidification hot cracking distribution and allowed for quantification of hot cracking susceptibility. To facilitate further research, a hot cracking susceptibility dataset has been established on Mendeley Data.
Article
Materials Science, Multidisciplinary
Ziheng Wu, Guannan Tang, Samuel J. Clark, Andrey Meshkov, Subhrajit Roychowdhury, Benjamin Gould, Victor Ostroverkhov, Thomas Adcock, Steven J. Duclos, Kamel Fezzaa, Christopher Immer, Anthony D. Rollett
Summary: In this study, in-situ X-ray imaging and high-fidelity modeling were used to investigate the keyhole dynamics in a kHz laser oscillation mode. The findings provide insights into the unique characteristics of the oscillating laser beam processing, which has implications for improving productivity, build quality, and controllable microstructure in laser-based additive manufacturing processes.
COMMUNICATIONS MATERIALS
(2023)
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.
Review
Physics, Multidisciplinary
Cang Zhao, Bo Shi, Shuailei Chen, Dong Du, Tao Sun, Brian J. Simonds, Kamel Fezzaa, Anthony D. Rollett
Summary: In the laser powder bed fusion additive manufacturing of metals, extreme thermal conditions create many highly dynamic physical phenomena. The melting modes are used as a guideline for printing, but there is no consistent and common definition due to limitations in measurement techniques. Process-based definitions of melting modes provide new guidelines for laser additive manufacturing practices and offer new research directions. The significance of the keyhole in enhancing laser energy absorption is highlighted.
REVIEWS OF MODERN PHYSICS
(2022)
