Article
Multidisciplinary Sciences
Qi Zhu, Qishan Huang, Yanzhong Tian, Shuchun Zhao, Yingbin Chen, Guang Cao, Kexing Song, Yanjun Zhou, Wei Yang, Ze Zhang, Xianghai An, Haofei Zhou, Jiangwei Wang
Summary: This study investigates the intrinsic deformability of defective twin boundaries in metallic materials and finds that inherent kinks on twin boundaries can facilitate the formation of secondary and hierarchical nanotwins. This defect-driven hierarchical twinning propensity is critically dependent on the kink height and is generally applicable in various metals and alloys.
Article
Materials Science, Multidisciplinary
Alexander Bergsmo, Yilun Xu, Benjamin Poole, Fionn P. E. Dunne
Summary: The study found that non-metallic inclusions and twin boundaries are preferred locations for fatigue crack nucleation in polycrystalline Ni-based superalloys. Through a multi-scale modelling strategy, the mechanism of fatigue crack nucleation was analyzed, revealing the involvement of inclusion fracture, twin boundary slip activation, and the accumulation of local geometrically necessary dislocations. These factors ultimately lead to the formation of fatigue cracks.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2022)
Article
Multidisciplinary Sciences
Qi Zhu, Lingyi Kong, Haiming Lu, Qishan Huang, Yingbin Chen, Yue Liu, Wei Yang, Ze Zhang, Frederic Sansoz, Haofei Zhou, Jiangwei Wang
Summary: The research reveals the unprecedented shear deformability of twins in nanocrystals, with extreme shear deformability up to 364% through TB sliding. The study shows that sliding-induced plasticity is orientation-dependent and relies critically on geometric inhomogeneities, which has implications for improving metal processing by severe plastic deformation.
Article
Materials Science, Multidisciplinary
Jingpeng Hou, Keliang Qiu, Fengshi Li, Zhenyu Yang, Yonghai Yue, Yongjun Tian, Zhongchang Wang, Lin Guo
Summary: Twin boundary (TB) is a special and fundamental internal interface that alters the mechanical and physical properties of materials. The deformation mechanism of TB and its effect on material strength and plasticity are still under debate. This study discovered that the pseudoelastic strain of a TB can recover with decomposition and escape of pile-up dislocations, which opens up new possibilities for optimizing material properties by manipulating twin boundaries at the nanoscale.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2023)
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
Vahid Samaee, Maxime Dupraz, Thomas Pardoen, Helena Van Swygenhoven, Dominique Schryvers, Hosni Idrissi
Summary: In-situ transmission electron microscopy observations in nickel bi-crystal samples provide insights into the formation of constriction nodes at coherent twin boundaries (CTBs) by the absorption of curved screw dislocations, leading to a unique CTB sliding mechanism involving coordinated twinning dislocation pairs. The interactions between non-screw dislocations and CTBs highlight the importance of the synergy between the repulsive force of CTBs and the back stress from single arm dislocation sources (SASs) in small volumes. The findings contribute to the understanding of the mechanisms controlling the strength and ductility of metals at coherent twin boundaries.
NATURE COMMUNICATIONS
(2021)
Article
Engineering, Mechanical
Xin-Yao Li, Ya-Fang Guo, Yong Mao, Xiao-Zhi Tang
Summary: The nucleation and growth of {1011} twin in Mg single crystal are investigated through molecular dynamics simulations. The twin embryo is found to be naturally nucleated at the free surface via dislocation slip, and its growth involves the formation of basal stacking faults.
INTERNATIONAL JOURNAL OF PLASTICITY
(2022)
Review
Chemistry, Physical
Takahito Ohmura, Masato Wakeda
Summary: The paper discusses the phenomenon of pop-in during indentation-induced deformation at a very small scale, emphasizing its importance as a fundamental deformation behavior in various materials and analyzing its mechanical and physical principles.
Article
Materials Science, Multidisciplinary
Yu Tian, Facai Ren, Fei Chen
Summary: This study uses molecular dynamics simulations to investigate the deformation mechanisms and interaction between twin boundaries and grain boundaries in gradient nano-grained materials. The findings have significant implications for understanding the strength characteristics of heterostructured materials.
MATERIALS TODAY COMMUNICATIONS
(2022)
Article
Chemistry, Multidisciplinary
Hongbo Xie, Hucheng Pan, Junyuan Bai, Dongsheng Xie, Peijun Yang, Shanshan Li, Jianfeng Jin, Qiuyan Huang, Yuping Ren, Gaowu Qin
Summary: The study discovered three- and five-layered discontinuous segregation patterns in twin boundaries in alloys, where not all sites are occupied by solutes larger than Mg, with some larger solutes taking compression sites. Nd/Mn solutes selectively segregate at substitutional sites, generating two new types of ordered two-dimensional TB superstructures or complexions.
Article
Engineering, Mechanical
Chunhui Wang, Chaoyang Sun, Wang Cai, Lingyun Qian, Xiangru Guo, M. W. Fu
Summary: This study developed a discrete dislocation plasticity (DDP) model that incorporates two twin nucleation mechanisms and introduces the effect of stacking fault energy on partial dislocation motion. The evolution of partial dislocation slip-mediated deformation twins in micron-sized pillars of twinning-induced plasticity steel was investigated using DDP simulation, showing agreement with experimental results. The research advances the understanding of partial dislocation slip-mediated twinning mechanisms by considering the competition between new twin activation and near-twin merging in determining the evolution of twin thickness.
INTERNATIONAL JOURNAL OF PLASTICITY
(2022)
Article
Materials Science, Multidisciplinary
Reza Hosseinabadi, Heinz Riesch-Oppermann, James P. Best, Gerhard Dehm, Christoph Kirchlechner
Summary: The impact of a coherent twin boundary (CTB) on the size scaling of shear stress in micropillar compression tests has been investigated. The study found that the CTB has a size-dependent contribution to shear stress, with a more prominent effect observed in smaller pillars.
Article
Multidisciplinary Sciences
Tao Meng, Pingping Sun, Feng Yang, Jie Zhu, Baoguang Mao, Lirong Zheng, Minhua Cao
Summary: This study investigates the use of bulk defects (FPDs) to improve the surface properties of metallic cobalt catalysts for the oxygen reduction reaction (ORR). The introduction of FPDs creates a unique type of surface catalytic site with concave geometry and compressive strain, which weakens oxygen binding. The catalyst exhibits excellent activity and stability in metal-air batteries and fuel cells, making it a promising alternative to precious metal catalysts.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Nanoscience & Nanotechnology
Junfeng Cui, Liang Ma, Guoxin Chen, Nan Jiang, Peiling Ke, Yingying Yang, Shiliang Wang, Kazuhito Nishimura, Javier Llorca
Summary: This article reports the abnormal phenomenon that twin boundaries weaken the strength of body-centered cubic (BCC) tungsten. [1-11]-oriented W nanowires with (121) twin planes and free of dislocations were fabricated, and in situ tensile tests were performed. The fracture strength of the twinned W nanowire was found to be 13.7 GPa, 16% lower than that of the single-crystal W nanowire (16.3 GPa). The weakening mechanism was revealed to be the early nucleation of a crack at the intersection of the twin boundary with the surface.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Chemistry, Physical
Min Huang, Pengcheng Zhai, Sergey I. Morozov, William A. Goddard, Guodong Li, Qingjie Zhang
Summary: Nanotwinning can significantly enhance the ductility of PbTe by promoting the migration of coherent twin boundaries at room temperature. The mechanical properties of nanotwinned PbTe, including yield strength and shear strength, are influenced by the shear direction, CTB orientation, and temperature. By examining these factors, it is possible to improve the mechanical strength or ductility of PbTe.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
