Article
Materials Science, Multidisciplinary
Ian Chesser, Elizabeth Holm, Brandon Runnels
Summary: This study reinterprets the problem of atomic displacement minimization during grain boundary migration as an optimal transport problem, applying the principle of stationary action to determine the Wasserstein metric for GB migration. The predicted optimal displacement patterns based on a forward model are compared to molecular dynamics data to test the minimum distance hypothesis. The results discuss the limitations of the hypothesis and the interesting consequences of the OT formulation in analyzing MD data for various types of grain boundaries.
Article
Nanoscience & Nanotechnology
Zhifu Zhao, Fulei Chu, Yueguang Wei
Summary: Nanocrystalline iron exhibits complicated crack propagation behavior, influenced by factors such as grain size, intergranular decohesion, and crystal orientation. With a decrease in grain size, crack propagation tends to become more ductile.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Materials Science, Multidisciplinary
Hong He, Shangyi Ma, Shaoqing Wang
Summary: This study systematically investigated the <110> symmetric tilt grain boundaries (STGBs) in tungsten with different atomic densities and temperatures. It was found that STGBs with high Grin Boundary Energy (GBE) are poor sinks for interstitials, while those with low GBE are strong sinks. High temperature can promote the formation of GB complexions with local hexagonal or cubic structures, reducing the GBEs of certain STGBs. Additionally, a new analysis method based on effective interstice stacking was proposed to assess the interstitial absorption capacity of the STGBs.
JOURNAL OF NUCLEAR MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Guangya Li, Yang Yang, Boyuan Gou, Jinyu Zhang, Jiao Li, Yaqiang Wang, Lingfei Cao, Gang Liu, Xiangdong Ding, Jun Sun
Summary: By controlling the defects of coherent twin boundaries (CTBs) through Cr segregation at kinks and grain boundaries (GBs), high strength and excellent structural-mechanical stability can be achieved, providing a new perspective for the design of purified Cu alloys.
Article
Materials Science, Ceramics
Marion Borde, Allan Germain, Emeric Bourasseau
Summary: In this study, molecular dynamics and CRG empirical potential were used to investigate the symmetrical tilt grain boundaries around the [001] axis in UO2. The analysis of atomic structures obtained by simulation showed excellent agreement with the Read and Schokley model, predicting the existence of regular dislocations in these grain boundaries. The study also calculated the energy of formation and cleavage of the boundaries, as well as the energy of formation of Schottky defects and incorporation of xenon and krypton atoms near the boundaries, providing insights into how these properties evolve with different misorientation angles.
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
(2021)
Article
Materials Science, Multidisciplinary
Wenxue Ma, Yibin Dong, Miaosen Yu, Ziqiang Wang, Yong Liu, Ning Gao, Limin Dong, Xuelin Wang
Summary: This study investigates the evolution of atomic structures and related changes in energy state, atomic displacement, and free volume of symmetrical grain boundaries in body-centered cubic iron under external strain using molecular dynamics method. The results show that complete MD relaxations at high temperatures are necessary to obtain lower energy states of grain boundaries. Under external strain, two mechanisms for the failure of these grain boundaries are explored, including slip system activation, dislocation nucleation, and dislocation network formation induced by the external strain field or phase transformation from bcc to fcc structure under the effects of external strain.
Article
Chemistry, Physical
Xiao Xing, Jinxin Gou, Fengying Li, Yongcheng Zhang, Jie Cheng, Yaoyinqi Wang, Jianguo Liu, Gan Cui, Zili Li, Peifeng Zhang, Xiaoming Luo, Bingying Wang
Summary: The fracture strain of polycrystal alpha-iron was studied at different hydrogen concentrations and crystal sizes using molecular dynamics simulations. Increasing hydrogen concentration leads to decreased fracture resistance in fine crystal models compared to coarse grain models, indicating a shift in vulnerability areas in the welding heat-affected zone. The density of triple or multi-junctions of grain boundaries plays a crucial role in intergranular failure caused by hydrogen embrittlement.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2021)
Article
Materials Science, Multidisciplinary
Zheyuan Xing, Haidong Fan, Guozheng Kang
Summary: As an important micro-structure, grain boundary plays a significant role in the micro-structure evolution and mechanical property of metallic materials. This study investigates the propagation mechanisms of intergranular cracks along [1100] symmetric tilt grain boundaries in magnesium bicrystals under tensile loading conditions using comprehensive molecular dynamics simulations, considering the effects of grain boundary misorientation angle, temperature, and solid solution.
COMPUTATIONAL MATERIALS SCIENCE
(2022)
Article
Engineering, Manufacturing
Pengyue Zhao, Jianwei Wu, Hongfei Chen, Huan Liu, Duo Li, Jiubin Tan
Summary: The interaction mechanism between grain boundaries and subgrain boundaries in nano-cutting was investigated through molecular dynamics simulations. It was found that the extrusion action caused periodic formation and annihilation of subgrains in nano-grains, leading to continuous pile-up formation, stresses accumulation, elastic recovery of the machined surface, and periodic oscillation of processing force. This study provides insights for improving surface quality and mechanical properties of nanocrystalline materials in the nano-cutting process.
JOURNAL OF MANUFACTURING PROCESSES
(2021)
Review
Materials Science, Multidisciplinary
Liang Zhang, Zhihui Zhang, Xuan Zhang, Xiaoxu Huang
Summary: The high strength of nanocrystalline metals is of great interest, but their low ductility and microstructural instability pose challenges. Previous experimental works have shown that grain boundary segregation of solute atoms can overcome these disadvantages. However, the microscopic mechanisms are not well understood yet. Computational simulation has provided insights into the effects of solute atoms on the structure, energy, and mechanical properties of segregated grain boundaries in nanocrystalline metals.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2022)
Article
Nanoscience & Nanotechnology
S. W. Wu, T. Yang, B. X. Cao, J. H. Luan, Y. F. Jia, L. Xu, Y. K. Mu, T. L. Zhang, H. J. Kong, X. Tong, J. C. Peng, G. Wang, Q. J. Zhai, J. Lu, C. T. Liu
Summary: A novel precipitation-strengthened multicomponent high-entropy alloy was designed with optimized grain boundaries, showing a transition from brittleness to ductility and significantly improving both strength and ductility of the material.
SCRIPTA MATERIALIA
(2021)
Article
Materials Science, Multidisciplinary
Debdas Roy, Snehanshu Pal, Chandra Sekhar Tiwary, Ashish Kumar Gupta, Pokula Narendra Babu, Rahul Mitra
Summary: This study investigates the stability and strength of nano-crystalline Cu alloys at high temperatures, achieved through cryomilling and hot pressing. Results show that the addition of 1% W in the Cu matrix can effectively restrict grain growth, leading to higher hardness, strength, and strain to failure in the alloy.
PHILOSOPHICAL MAGAZINE
(2022)
Article
Chemistry, Physical
Wei Huang, Kailin Pan, Bo Wang, Yubing Gong
Summary: The effects of grain size on the mechanical properties of polycrystalline Cu6Sn5 were investigated using molecular dynamics simulations. The results showed that at low strain rates, increasing grain size led to an increase in Young's modulus, yield stress, and ultimate tensile strength, due to the weakening of grain boundaries interactions caused by sliding and rotation. However, at high strain rates, the influence of grain size on the mechanical properties was minimal.
Article
Materials Science, Multidisciplinary
Da Wang, Sirui Liu, Changquan Xiao, Xianfeng Ma, Yulin Sun, Ganfeng Yuan, Jun Zeng, Yuqiang Liang, Yanying Hu, Fenglei Niu, Xing Gong
Summary: The corrosion mechanism of 15-15Ti and 316Ti austenitic stainless steels exposed to liquid lead-bismuth eutectic (LBE) at 550 degrees C was studied. The oxides formed on the steels have a dual- or triplex-layered structure. Higher Cr content in the oxides inhibits Ni diffusion better. Local dissolution attack leads to the formation of a Ni-rich recrystallization area with fine grain fcc phase. Preferential intergranular oxidation (PIO) in random grain boundaries of 15-15Ti induces intergranular cracking, while annealing twin boundaries are more resistant to cracking. 316Ti with smaller grains shows higher corrosion resistance and intergranular cracking resistance.
Article
Nanoscience & Nanotechnology
L. A. Barrales-Mora, Y. Tokuda, D. A. Molodov, S. Tsurekawa
Summary: The experimental and simulation results indicate that the ability of grain boundaries to act as a barrier for the motion of incoming dislocations crucially depends on grain boundary structure.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
