Article
Materials Science, Multidisciplinary
Christopher Barrett, Jose Martinez, Mashroor Nitol
Summary: Twin-twin interactions play a crucial role in the microstructural evolution of hexagonal close-packed metals during plasticity. However, the characterization of the atomic-scale behavior of interacting twins has been limited. In this study, a three-dimensional model based on interfacial defect theory was developed to characterize twin-twin interactions and other complex interfacial reactions. Molecular dynamics simulations were conducted on titanium, showing excellent agreement with the model. Surprisingly, highly ordered and mobile boundaries were produced by these complex reactions, which could provide important insights for higher scale models of plasticity.
Article
Materials Science, Multidisciplinary
Javier Varillas, Jan Ocenasek, Jordi Torner, Jorge Alcala
Summary: Nanoindentation experiments in various metals show the onset of plastic instabilities, formation of permanent nanoimprints and defect networks. Molecular dynamics simulations reveal the processes governing contact resistance, abrupt plastic instabilities, and the evolution towards a steady-state with plateauing hardness. The ratio of hardness to Young's modulus varies between different metals, with BCC Ta and Fe showing higher values. Factors such as stacking faults, nanotwin interlocking, and defect remobilization events contribute to the formation of permanent nanoimprints. Additionally, the correlation between nanoimprint formation and material response to indentation influences the hardness to yield strength ratio, exceeding the continuum plasticity bound.
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
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
G. Gengor, A. S. K. Mohammed, H. Sehitoglu
Summary: The study focuses on the mechanical properties of HCP alloys and uncovers the atomistic mechanism of a prominent twin mode in HCP materials. It establishes the initial twin boundary structure and determines the twin boundary migration mechanism. The calculated Generalized Planar Fault Energy curves show high unstable energies and low migration barriers for twinning in HCP metals.
Article
Materials Science, Multidisciplinary
Gorkem Gengor, Ahmed Sameer Khan Mohammed, Huseyin Sehitoglu
Summary: This study resolves the long-standing debate over the Twin Boundary (TB) structure and twinning mechanism in HCP materials by utilizing Crystallographic Analytical Methods (CAM), Molecular Statics (MS) simulations, and Density Functional Theory (DFT) calculations. By establishing an energy-minimizing lattice-offset between the twin and matrix, the correct TB structure, twinning mechanism, and energy barriers are determined. The study also calculates Generalized Planar Fault Energy (GPFE) for the first time, revealing energy barriers for twin nucleation and migration, highlighting their importance in predictive twinning models.
Article
Materials Science, Multidisciplinary
Nicolo Grilli, Alan C. F. Cocks, Edmund Tarleton
Summary: Fractures arising from cracks nucleating and propagating along twin boundaries in metals are studied using simulations and numerical models in this study. The interaction between twin systems and the mechanism of crack formation are investigated to understand the fracture behavior caused by the activation of multiple twin systems.
INTERNATIONAL JOURNAL OF FRACTURE
(2022)
Article
Nanoscience & Nanotechnology
Zongde Kou, Rong Huang, Yanqing Yang, Tao Feng, Song Tang, Si Lan, Lixia Yang
Summary: This study investigates the evolution of sessile disconnections on twin boundaries through experimental, analytical, and simulation approaches. The results show that sessile disconnections can serve as nucleation sites for twinning dislocations and lead to the migration of twin boundaries. Additionally, twin-twin intersections can transform gliding lattice dislocations into twinning dislocations.
SCRIPTA MATERIALIA
(2022)
Article
Materials Science, Multidisciplinary
Filip Siska, Ludek Stratil, Jan Cizek, Tingting Guo, Matthew Barnett
Summary: This paper investigates the interactions between {10 (1) over bar2} ten sile twin and precipitates aligned along basal planes in magnesium alloys. The results show that precipitates influence the shear stress necessary to accommodate twins, and the thickness of precipitates plays a crucial role in twin thickening and propagation.
Article
Chemistry, Physical
Binting Huang, Jishi Yang, Zhiheng Luo, Yang Wang, Nan Wang
Summary: The rapid solidification process often leads to high-density microstructure defects and residual thermal stress in metals. Twin boundaries, which are potentially beneficial, have been observed in rapidly solidified nanocrystalline microstructures. This study proposes a pathway for forming twin boundaries and provides a detailed derivation of strain inhomogeneities and the deformation twinning phase field method. By calculating the cooling-induced thermal strain inhomogeneity and growth thresholds for deformation twinning, it is shown that residual thermal strain hotspots in the microstructure can reach the threshold for deformation twinning when there is a significant difference in shear elastic property between grain boundaries and the bulk material.
Article
Multidisciplinary Sciences
Cong He, Zhiqiao Li, Houwen Chen, Nick Wilson, Jian-Feng Nie
Summary: The authors report an unusual solute segregation phenomenon in a group of Mg alloys driven by chemical bonding, where solute atoms larger than Mg segregate to compression sites of specific fully coherent twin boundary.
NATURE COMMUNICATIONS
(2021)
Article
Nanoscience & Nanotechnology
Khanh Dang, Carlos N. Tome, Laurent Capolungo
Summary: This study used atomistic simulations to investigate the 3-D structural characteristics and evolution of non-cozone {10 (1) over bar2} twin-twin junctions in magnesium. It discovered new twin-twin boundaries and discussed their impact on twin stability and mobility.
SCRIPTA MATERIALIA
(2021)
Article
Chemistry, Physical
Chongze Hu, Douglas L. Medlin, Remi Dingreville
Summary: Twin boundaries play a crucial role in nanocrystalline metals, and an unusual segregation phenomenon at gold-doped platinum twin boundaries is mediated by the presence of disconnections, leading to an unexpected structural transition at the atomic scale induced by faulted disconnections.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Amir Hassan Zahiri, Eduardo Vitral, Jamie Ombogo, Mehrab Lotfpour, Lei Cao
Summary: This study investigates the effect of mechanical loading on martensite microstructure and reveals the critical role of mechanical loading in the formation of specific transformation twinning, which could offer a novel strategy for engineering twin microstructure using designed thermomechanical processing.
Article
Metallurgy & Metallurgical Engineering
Qi Qian, Zheng-qing Liu, Yong Jiang, Yi-ren Wang, Xing-long An, Min Song
Summary: First-principles calculations were used to investigate the formation mechanism of GTBs in hcp Ti, revealing that GTBs can form from the gliding of CTBs and eventually restore CTB structures by forming twinning disconnections. The pile-up of twinning disconnections at twin boundaries can promote twin growth. Additionally, the study evaluated the possible effects of alloying elements on pinning twin boundaries in Ti alloys.
TRANSACTIONS OF NONFERROUS METALS SOCIETY OF CHINA
(2021)
Article
Materials Science, Multidisciplinary
Napoleon Anento, Anna Serra
COMPUTATIONAL MATERIALS SCIENCE
(2020)
Article
Materials Science, Multidisciplinary
Andriy Ostapovets, Konstantin Kushnir, Kristian Mathis, Filip Siska
Summary: Both types of obstacles inhibit twin growth and require increased stress to engulf them. However, the increase of critical resolved shear stress is higher for the interaction with a row of voids compared to non-shearable obstacles.
Article
Materials Science, Multidisciplinary
N. Kvashin, N. Anento, D. Terentyev, A. Bakaev, A. Serra
Summary: This paper analyzes the interaction of 1/2 <111> dislocation pileup with {332} tilt grain boundaries in three bcc metals, observing that the grain boundary can absorb crystal dislocations and form new dislocations and fractures, with the number of absorbed dislocations depending on the orientation of the Burgers vector and the material.
PHYSICAL REVIEW MATERIALS
(2021)
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
Materials Science, Multidisciplinary
N. Kvashin, N. Anento, D. Terentyev, A. Serra
Summary: The study revealed that {111} tilt grain boundary in iron can change orientation and act as a strong obstacle for gliding dislocations. The interaction between individual crystal dislocations and the grain boundary may lead to the deformation of the boundary or absorption of the dislocations, depending on the orientation of glide planes. Additionally, stress concentration from dislocation pile-ups enhances the reaction process of the grain boundary.
COMPUTATIONAL MATERIALS SCIENCE
(2022)
Article
Materials Science, Multidisciplinary
Ritu Verma, Lubomir Kral, Andriy Ostapovets
Summary: Recent studies have shown that the faceting of twin boundaries is common in hcp materials. Asymmetrical facets in twin interfaces are a result of the twin boundary migration mechanism. This mechanism is also applicable to less common {11 (2) over bar6} twins, with migration mediated by disconnections and nucleation of asymmetrical facets demonstrated through atomistic simulations and TEM images.
PHILOSOPHICAL MAGAZINE
(2022)
Article
Materials Science, Multidisciplinary
Pavel Pal-Val, Olena Vatazhuk, Andriy Ostapovets, Lubomir Kral, Jan Pinc
Summary: The study measured the acoustic properties of commercial grade magnesium in the temperature range of 51-310 K, finding that the properties were affected by thermally activated dislocation breakaway. The binding energy of the interaction between dislocations and defects was estimated, along with the dependences of the activation energy and activation volume on applied stress.
Article
Materials Science, Multidisciplinary
N. Kvashin, N. Anento, A. Serra
Summary: This paper presents a study on the disconnections in <110> tilt grain boundaries in bcc metals and their role in GB migration. The characteristics and behaviors of these disconnections in different types of GBs are examined.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
N. Kvashin, N. Anento, D. Terentyev, A. Serra
Summary: This paper studies the interaction between a pileup of 1/2 <111)> dislocations and the {112} tilt grain boundary (GB), as well as the interaction with twinning. The results show that the interacting dislocation is transformed into a GB or TB dislocation, causing shear-coupled GB migration. Furthermore, the {112} twin creates barriers to the motion of 1/2 <111)> dislocations.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Nanoscience & Nanotechnology
Andriy Ostapovets, Ritu Verma, Anna Serra
Summary: This study analyzes the recently proposed mechanism of {11 <(2) over bar > 2} twin nucleation in Ti by reverse phase transformation, showing the connection between nucleation and growth mechanism of twins with the possibility of phase transformation. The process involves the gliding of step-like defects along the {1122} boundary to mediate twin growth, with the shear of twins completed by the gliding of disconnections that convert the twin boundary structure between alternative variants.
SCRIPTA MATERIALIA
(2022)
Article
Materials Science, Multidisciplinary
N. Kvashin, D. Terentyev, A. Serra, N. Anento
Summary: This paper investigates the influence of irradiation defects on the plastic slip of grain boundaries and finds that these defects act as obstacles to the slip, resulting in the formation of residual defects.
COMPUTATIONAL MATERIALS SCIENCE
(2022)
Article
Materials Science, Multidisciplinary
Martin Zeleny, Andriy Ostapovets, Lucius Fridrich, Petr Sestak, Martin Heczko, Tomas Kruml
Summary: This article revisits the theory of mechanical twinning for face-centred tetragonal lattices and proposes a correction factor for determining the magnitude of the shearing vector. The theory is verified through ab initio calculations and it is found that the modification of the shearing vector is caused by structural optimization and cannot be simply predicted.
PHILOSOPHICAL MAGAZINE
(2023)
