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
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
Sebastian Herbst, Elvira Karsten, Gregory Gerstein, Silvia Reschka, Florian Nuernberger, Stefan Zaefferer, Hans Juergen Maier
Summary: The mechanisms of electroplastic effect (EPE) in different hexagonal close-packed (hcp) metals under varying loading conditions and current densities were investigated through flow curve analysis and microstructural changes. The investigations revealed significant changes in the forming behavior of hcp materials due to superimposed electric current impulses. This was attributed to the activation of additional dislocation types and formation of characteristic twin bands. The existence of a critical value of current density and its influence on the EPE were verified by experiments, with a magnitude corresponding to theoretical values of 1.6 to 2.0 kA mm(-2). The duration of pulses also had an influence on the EPE.
ADVANCED ENGINEERING MATERIALS
(2023)
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
Chemistry, Multidisciplinary
Hao Zhang, Bingqiang Wei, Xiaoqin Ou, Song Ni, Kechao Zhou, Min Song
Summary: This paper proposes a new formation route for face-centered cubic (FCC) twins at the hexagonal close-packed (HCP)/FCC interface in a deformed Ti-5at.%Al alloy. Experimental results and molecular dynamics simulations reveal the presence of FCC bands and lamellae with different orientation relationships within the HCP matrix, and suggest a {111} twinning relationship between these structures. The lattice correspondence analysis further explains the formation route for {111} twins based on crystal geometry.
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
(2022)
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
Chemistry, Multidisciplinary
Nikolai Zimber, Judith Lammer, Pavel Vladimirov, Gerald Kothleitner, Vicki J. Keast, Michael Duerrschnabel, Michael Klimenkov
Summary: The authors use transmission electron microscopy to show that hydrogen adsorbs directly at the (0001) surfaces of hexagonal helium bubbles within neutron irradiated beryllium. The results provide important insights into the interaction between hydrogen and metal surfaces at the nanoscale.
COMMUNICATIONS CHEMISTRY
(2023)
Article
Nanoscience & Nanotechnology
Jin-Kui Meng, Li Liu, Jian-Tang Jiang, Xing-Qi Liao, Xiang-Guang Chen, Liang Zhen
Summary: The mechanical behavior of commercially pure Ti under biaxial stress conditions has been investigated. It was found that prismatic slip was suppressed while pyramidal slip was promoted under high biaxial stress. The occurrence of extension twinning was also encouraged by the increased stress component in the c-axis direction. Deformation resistance and work hardening rate increased with increasing biaxiality.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Engineering, Mechanical
Liansong Dai, Weidong Song
Summary: This study proposes a novel crystal plasticity model to describe the mechanical behavior and microstructure evolution of HCP materials. A new flow rule is developed to incorporate the effects of strain rate and temperature on the activation of specific deformation mechanisms. Numerical simulations show that increasing strain rate or decreasing temperature promotes twinning over slip, resulting in more pronounced hardening and higher stress levels.
INTERNATIONAL JOURNAL OF PLASTICITY
(2022)
Article
Nanoscience & Nanotechnology
Shuo Zhou, Peng Chen, Min Zha, Yongfu Zhu, Bin Li, Hui-Yuan Wang
Summary: Atomistic simulations were conducted to investigate the interaction between prismatic dislocations and {1122} twin boundary in hexagonal close-packed titanium. Unusual and interesting dislocation transmutation was observed, where a (1010) 13 [1210] dislocation first transformed into a (0112) 3[2110] dislocation within the twin, which is not a common slip plane, and then further transformed into a prismatic dislocation (0110) 13 [2110] with lower line energy. This behavior, along with other prismatic dislocation transmutations, can be explained from the perspective of lattice correspondence in deformation twinning.
SCRIPTA MATERIALIA
(2023)
Article
Materials Science, Multidisciplinary
Jingwei Li, Manling Sui, Bin Li
Summary: This study investigated the twin boundary structure in deformed pure titanium using STEM observations and atomistic simulations. The results showed that the twinning dislocation only involves a single twinning plane and the K-2 plane is (0002), which is consistent with the atomistic simulations. The study also revealed a unique half-shear-half-shuffle process in the formation of the twin boundary structure, providing insights into the lattice correspondences and resolving the conflict between classical twinning theory prediction and simulation results.
Article
Physics, Multidisciplinary
Michael Peper, Johannes Deiglmayr
Summary: In this study, homonuclear Cs-2, K-2, and heteronuclear CsK long-range Rydberg molecules were formed in a dual-species magneto-optical trap for K-39 and Cs-133 by one-photon UV photoassociation. The different ground-state-density dependence of homo- and heteronuclear photoassociation rates and the detection of stable molecular ions provided clarification. Bound-bound millimeter-wave spectroscopy of long-range Rydberg molecules was utilized to access molecular states not accessible by one-photon photoassociation, serving as a benchmark for the development of theoretical models.
PHYSICAL REVIEW LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Yan Ma, Muxin Yang, Fuping Yuan, Xiaolei Wu
Summary: Deformation-induced hcp nano-lamellae were observed in the CoCrNi medium-entropy alloy under high strain rate and cryogenic temperature, leading to higher hardness compared to room temperature-deformed samples. Molecular dynamics simulations revealed that both phase strengthening and extra interface strengthening contribute to the overall strengthening, with the interface strengthening always stronger. Samples with smaller interspacing of hcp nano-lamellae showed higher strength due to increased density of phase boundaries and newly formed twin boundaries.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2021)
Article
Mechanics
Di Liu, Donglai Liu, Hailong Chen
Summary: This paper presents a novel nonlocal lattice particle method for full-field modeling of hexagonal close-packed (HCP) single crystals using reformulations of conventional continuum theories. The interaction between material particles in this method is nonlocal, and depends not only on the deformation states of the two particles, but also on the deformation states of all their neighbors. Equivalency assumptions are made to determine the material particle interaction for mechanical, thermal, and thermal-mechanical coupling problems. Numerical studies show good agreements between the results from the proposed method and the conventional continuum theories.
INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES
(2023)
Article
Chemistry, Physical
Ahmed Sameer Khan Mohammed, Huseyin Sehitoglu, Richard Rateick
Article
Materials Science, Multidisciplinary
Ahmed Sameer Khan Mohammed, Huseyin Sehitoglu
Article
Materials Science, Multidisciplinary
Ahmed Sameer Khan Mohammed, Huseyin Sehitoglu
Article
Microscopy
F. Brenne, A. S. K. Mohammed, H. Sehitoglu
Article
Materials Science, Multidisciplinary
Ahmed Sameer Khan Mohammed, Huseyin Sehitoglu
Summary: The study explores the complexity and evolution capability of twin boundaries in NiTi, revealing the energy-minimal nanostructure and evolutionary mechanism of interface topology through the combination of multiscale energetics and theoretical frameworks.
Article
Materials Science, Multidisciplinary
R. Sidharth, A. S. K. Mohammed, W. Abuzaid, H. Sehitoglu
Summary: Shape memory alloys can be used in damping applications, with temperature changes during load/unload cycles affecting their mechanical response. Fe43.5Mn34Al15Ni7.5 shows rate insensitivity, while Ni50.8Ti exhibits high rate sensitivity.
SHAPE MEMORY AND SUPERELASTICITY
(2021)
Article
Engineering, Mechanical
Jessica A. Krogstad, Huseyin Sehitoglu, Orcun Koray Celebi, Ahmed Sameer Khan Mohammed
Summary: This article introduces an analytical Evolving Dislocation Core (EDC) model devoid of empiricism, capable of predicting the elevation of Critical Resolved Shear Stresses (CRSS) for any reaction. The model shows agreement with atomistic simulations and experimental results, and establishes a strong correlation between the CRSS elevation and unstable stacking/twinning fault energy and the magnitude of the sessile dislocation's Burgers vector.
INTERNATIONAL JOURNAL OF PLASTICITY
(2022)
Article
Engineering, Mechanical
Daegun You, Orcun Koray Celebi, Ahmed Sameer Khan Mohammed, Diab W. Abueidda, Seid Koric, Huseyin Sehitoglu
Summary: A predictive model is developed to accurately predict the dislocation glide stress in FCC materials, considering the anisotropic continuum energy, the atomistic misfit energy, and the minimum energy path for the intermittent motion of Shockley partials. By generating a large material dataset and using machine learning, the model achieves a 94% accuracy in predicting the critical resolved shear stress for 1033 materials, revealing the sensitivity of material parameters to the predicted stress.
INTERNATIONAL JOURNAL OF PLASTICITY
(2023)
Article
Materials Science, Multidisciplinary
Orcun Koray Celebi, Ahmed Sameer Khan Mohammed, Huseyin Sehitoglu
Summary: This study proposes a predictive model that can accurately predict the glide stress of a dissociated dislocation in a face-centered cubic (FCC) material. The model takes into account the material's elastic anisotropy and the dislocation core-width, and corrects the overestimation of slip plane area in previous experimental studies. The results show that the character of the dissociated dislocation has a significant influence on the glide stress.
Article
Materials Science, Multidisciplinary
Y. Liu, K. Zweiacker, C. Liu, J. T. McKeown, J. M. K. Wiezorek
Summary: The evolution of rapid solidification microstructure and solidification interface velocity of hypereutectic Al-20at.%Cu alloy after laser melting has been studied experimentally. It was found that the formation of microstructure was dominated by eutectic, alpha-cell, and banded morphology grains, and the growth modes changed with increasing interface velocity.
Article
Materials Science, Multidisciplinary
Bharat Gwalani, Julian Escobar, Miao Song, Jonova Thomas, Joshua Silverstein, Andrew Chihpin Chuang, Dileep Singh, Michael P. Brady, Yukinori Yamamoto, Thomas R. Watkins, Arun Devaraj
Summary: Castable alumina forming austenitic alloys exhibit superior creep life and oxidation resistance at high temperatures. This study reveals the mechanism behind the enhanced creep performance of these alloys by suppressing primary carbide formation and offers a promising alloy design strategy for high-temperature applications.
Article
Materials Science, Multidisciplinary
Jian Song, Qi Zhang, Songsong Yao, Kunming Yang, Houyu Ma, Jiamiao Ni, Boan Zhong, Yue Liu, Jian Wang, Tongxiang Fan
Summary: Recent studies have shown that achieving an atomically flat surface for metals can greatly improve their oxidation resistance and enhance their electronic-optical applications. Researchers have explored the use of graphene as a covering layer to achieve atomically flat surfaces. They found that high-temperature deposited graphene on copper surfaces formed mono-atomic steps, while annealed copper and transferred graphene on copper interfaces formed multi-atomic steps.
Article
Materials Science, Multidisciplinary
Jennifer A. Glerum, Jon-Erik Mogonye, David C. Dunand
Summary: Elemental powders of Al, Ti, Sc, and Zr are blended and processed via laser powder-bed fusion to create binary and ternary alloys. The microstructural analysis and mechanical testing show that the addition of Ti results in the formation of primary precipitates, while the addition of Sc and Zr leads to the formation of fine grain bands. The Al-0.25Ti-0.25Zr alloy exhibits comparable strain rates to Al-0.5Zr at low stresses, but significantly higher strain rates at higher stresses during compressive creep testing. Finite element modeling suggests that the connectivity of coarse and fine grain regions is a critical factor affecting the creep resistance of the alloys.
Article
Materials Science, Multidisciplinary
P. Jannotti, B. C. Hornbuckle, J. T. Lloyd, N. Lorenzo, M. Aniska, T. L. Luckenbaugh, A. J. Roberts, A. Giri, K. A. Darling
Summary: This work characterizes the thermo-mechanical behavior of bulk nanocrystalline Cu-Ta alloys under extreme conditions. The experiments reveal that the alloys exhibit unique mechanical properties, behaving differently from conventional nanocrystalline Cu. They do not undergo grain coarsening during extrusion and exhibit behavior similar to coarse-grained Cu.
Article
Materials Science, Multidisciplinary
Yiqing Wei, Jingwei Li, Daliang Zhang, Bin Zhang, Zizhen Zhou, Guang Han, Guoyu Wang, Carmelo Prestipino, Pierric Lemoine, Emmanuel Guilmeau, Xu Lu, Xiaoyuan Zhou
Summary: This study proposes a new strategy to modify microstructure by phase regulation, which can simultaneously enhance carrier mobility and reduce lattice thermal conductivity. The addition of Cu in layered SnSe2 induces a phase transition that leads to increased grain size and reduced stacking fault density, resulting in improved carrier mobility and lower lattice thermal conductivity.
Article
Materials Science, Multidisciplinary
Jia Chen, Zhengyu Zhang, Eitan Hershkovitz, Jonathan Poplawsky, Raja Shekar Bhupal Dandu, Chang-Yu Hung, Wenbo Wang, Yi Yao, Lin Li, Hongliang Xin, Honggyu Kim, Wenjun Cai
Summary: In this study, the structural origin of the pH-dependent repassivation mechanisms in multi-principal element alloys (MPEA) was investigated using surface characterization and computational simulations. It was found that selective oxidation in acidic to neutral solutions leads to enhanced nickel enrichment on the surface, resulting in reduced repassivation capability and corrosion resistance.
Article
Materials Science, Multidisciplinary
X. Y. Xu, C. P. Huang, H. Y. Wang, Y. Z. Li, M. X. Huang
Summary: The limited slip systems of magnesium (Mg) and its alloys hinder their wide applications. By conducting tensile straining experiments, researchers discovered a rate-dependent transition in the dislocation mechanisms of Mg alloys. At high strain rates, glissile dislocations dominate, while easy-glide dislocations dominate at low strain rates. Abundant glissile dislocations do not necessarily improve ductility.
Article
Materials Science, Multidisciplinary
M. S. Szczerba, M. J. Szczerba
Summary: Inverse temperature dependences of the detwinning stress were observed in face-centered cubic deformation twins in Cu-8at.%Al alloy. The detwinning stress increased with temperature when the pi detwinning mode was involved, but decreased when the pi/3 mode was involved. The dual effect of temperature on the detwinning stress was due to the reduction of internal stresses pre-existing within the deformation twins. The complete reduction of internal stresses at about 530 degrees C led to the equivalence of the critical stresses of different detwinning modes and a decrease in the yield stress anisotropy of the twin/matrix structure.
Article
Materials Science, Multidisciplinary
Taowen Dong, Tingting Qin, Wei Zhang, Yaowen Zhang, Zhuoran Feng, Yuxiang Gao, Zhongyu Pan, Zixiang Xia, Yan Wang, Chunming Yang, Peng Wang, Weitao Zheng
Summary: The interaction between the electrode and the electric double layer (EDL) significantly influences the energy storage mechanism. By studying the popular alpha-Fe2O3 electrode and the EDL interaction, we find that the energy storage mechanism of the electrode can be controlled by modulating the EDL.
Article
Materials Science, Multidisciplinary
Matthew R. Barnett, Jun Wang, Sitarama R. Kada, Alban de Vaucorbeil, Andrew Stevenson, Marc Fivel, Peter A. Lynch
Summary: The elastic-plastic transition in magnesium alloy Mg-4.5Zn exhibits bursts of deformation, which are characterized by sudden changes in grain orientation. These bursts occur in a coordinated manner among nearby grains, with the highest burst rate observed at the onset of full plasticity. The most significant burst events are associated with twinning, supported by the observation of twinned structures using electron microscopy. The bursts are often preceded and followed by a stasis in peak movement, indicating a certain "birth size" for twins upon formation and subsequent growth at a later stage.
Article
Materials Science, Multidisciplinary
Vaidehi Menon, Sambit Das, Vikram Gavini, Liang Qi
Summary: Understanding solute segregation thermodynamics is crucial for investigating grain boundary properties. The spectral approach and thermodynamic integration methods can be used to predict solute segregation behavior at grain boundaries and compare with experimental observations, thus aiding in alloy design and performance control.
Article
Materials Science, Multidisciplinary
Feiyu Qin, Lei Hu, Yingcai Zhu, Yuki Sakai, Shogo Kawaguchi, Akihiko Machida, Tetsu Watanuki, Yue-Wen Fang, Jun Sun, Xiangdong Ding, Masaki Azuma
Summary: This study reports on the negative and zero thermal expansion properties of Cd2Re2O7 and Cd1.95Ni0.05Re2O7 materials, along with their ultra-low thermal conductivity. Through investigations of their structures and phonon calculations, the synergistic effect of local structure distortion and soft phonons is revealed as the key to achieving these distinctive properties.
Article
Materials Science, Multidisciplinary
Thomas Beerli, Christian C. Roth, Dirk Mohr
Summary: A novel testing system for miniature specimens is designed to characterize the plastic response of materials for which conventional full-size specimens cannot be extracted. The system has an automated operation process, which reduces the damage to specimens caused by manual handling and improves the stability of the test results. The experiments show that the miniature specimens extracted from stainless steel and aluminum have high reproducibility, and the results are consistent with those of conventional-sized specimens. A correction procedure is provided to consider the influence of surface roughness and heat-affected zone caused by wire EDM.
Article
Materials Science, Multidisciplinary
Rani Mary Joy, Paulius Pobedinskas, Nina Baule, Shengyuan Bai, Daen Jannis, Nicolas Gauquelin, Marie-Amandine Pinault-Thaury, Francois Jomard, Kamatchi Jothiramalingam Sankaran, Rozita Rouzbahani, Fernando Lloret, Derese Desta, Jan D'Haen, Johan Verbeeck, Michael Frank Becker, Ken Haenen
Summary: This study investigates the influence of film microstructure and composition on the Young's modulus and residual stress in nanocrystalline diamond thin films. The results provide insights into the mechanical properties and intrinsic stress sources of these films, and demonstrate the potential for producing high-quality nanocrystalline diamond films under certain conditions.
