Article
Materials Science, Multidisciplinary
Mingjun Yang, Andrey Orekhov, Zhi-Yi Hu, Man Feng, Shenbao Jin, Gang Sha, Kai Li, Vahid Samaee, Min Song, Yong Du, Gustaaf Van Tendeloo, Dominique Schryvers
Summary: In-situ TEM experiments revealed that coherent beta'' precipitates in Al alloys are sheared into small fragments by dislocations, while semi-coherent beta' precipitates are more difficult to be fragmented and can maintain their shape after tensile deformation.
Article
Materials Science, Multidisciplinary
Sijing Chen, Fei Liu, Boyu Liu, Xiao Chen, Xiaoxing Ke, Manchen Zhang, Xiaochang Tang, Pengfei Guan, Ze Zhang, Zhiwei Shan, Qian Yu
Summary: By utilizing electron beam irradiation to modify the uneven surface of MgO NPs, surface nano-crystallization can be achieved, leading to an increase in compressive strength and approaching the theoretical strength of the material. This study demonstrates that imperfections in materials can be homogenized to optimize properties to approach that of perfect crystals.
Article
Engineering, Multidisciplinary
YanXiang Liang, XiaoFang Yang, KaiSheng Ming, ShiHua Xiang, Qing Liu
Summary: The deformation mechanism of CoCrNi alloy with high density of annealing twins was studied by in situ transmission electron microscopy. It was observed that dislocation transmission and reflection at twin boundaries occurred during in situ loading. These processes not only strengthen the material by impeding dislocation motion, but also act as dislocation sources to generate numerous slip bands.
SCIENCE CHINA-TECHNOLOGICAL SCIENCES
(2021)
Article
Nanoscience & Nanotechnology
Benjamin Galy, Michael Musi, Muriel Hantcherli, Guy Molenat, Alain Couret, Petra Spoerk-Erdely, Helmut Clemens, Jean-Philippe Monchoux
Summary: In this study, dislocation velocities in metallic systems were measured at high temperatures, with simultaneous determination of the corresponding mechanism. Coupled experiments of in-situ TEM investigations and stereographic analyses were conducted in an intermetallic alloy, identifying both mixed climb and pure glide mechanisms. The results showed that within a transition temperature domain, mixed climb can reach the velocity of glide, with dislocation velocities in the same order of magnitude (0.5-5 nm/s).
SCRIPTA MATERIALIA
(2023)
Article
Materials Science, Multidisciplinary
Xiaoqing Li, John Turner, Karen Bustillo, Andrew M. Minor
Summary: The study utilized in situ TEM to observe nanostructural changes in single crystal nickel under mechanical and electrical stimuli to elucidate the mechanisms of electroplasticity. Findings indicate that pulsed electrical current delays stress concentration formation and leads to more uniform plasticity deformation.
Article
Materials Science, Multidisciplinary
M. Larranaga, S. Lartigue-Korinek, M. Legros, N. Combe, F. Mompiou
Summary: Coherent twin boundaries play a crucial role in strengthening structural materials by impeding dislocation motion. However, the relaxation and deformation processes at high temperatures are not fully understood due to complex dislocation decomposition and motion mechanisms. In this study, shear-coupled motion of a coherent twin in pure Al is explored during in situ straining using a transmission electron microscope (TEM). Surprisingly, the twin boundary does not couple to shear but slightly migrates through nanoscale incoherent facets, and extensive dislocation/grain boundary interactions are observed.
Article
Nanoscience & Nanotechnology
Xiaoqing Li, Andrew M. Minor
Summary: The study demonstrates a technique for observing the nucleation of individual dislocations during in situ TEM tensile testing and measuring fundamental parameters relevant for plasticity. By systematically detecting dislocation slip traces with automated image analysis in an oriented single crystal Ni sample, the research provides a method for correlating dislocation nucleation events with stress levels. The analysis enables the extrapolation of activation parameters for individual dislocation nucleation events, offering direct quantitative measurements useful for computational models of plasticity.
SCRIPTA MATERIALIA
(2021)
Article
Nanoscience & Nanotechnology
Kang Yan, Zhongwei Chen, Wenjie Lu, Yanni Zhao, Wei Le, YanQing Xue, Sufyan Naseem, Ali Wafaa
Summary: In-situ tension test in a transmission electron microscope was used to study the fracture process of aluminium, finding that multiple Frank-Read dislocation sources are formed in the crystal thinning area at the front of the crack, leading to the nucleation of nanocracks. Continuous perfect dislocations emitted from the crack tip slip, decompose, and form twin boundaries, with residual dislocations forming dislocation walls and stacking faults, ultimately causing slip at the twin boundary.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Materials Science, Multidisciplinary
V. Vojtech, I. Basu, J. M. Wheeler, R. E. Schaublin, J. F. Loffler
Summary: In this study, the origins of mechanical property degradation in Fe-Cr alloys with different microstructures were examined using experiments and nanoscale structural characterization. It was found that the plasticity mechanisms changed fundamentally across different microstructures, and correlations between the fluctuations in Cr and the plasticity dynamics were established. The phase-separation effect, although promoting strengthening, was not the primary cause of embrittlement, but rather enhanced ductility.
Article
Nanoscience & Nanotechnology
Kang Yan, Zhongwei Chen, Yanni Zhao, Wei Le, Yanqing Xue, Sufyan Naseem, Ali Wafaa
Summary: Deformation twinning is an important phenomenon in the plastic deformation of metals and alloys, alongside dislocation slip. In this study, the plastic deformation behavior of coarse-grained aluminum with high stacking fault energy was investigated using in-situ tensile TEM. The findings reveal that deformation twins occur at the crack tip under continuous applied stress, with the thickness of deformation twin increasing as incoherent twin boundaries (ITBs) appear. Analysis shows that Frank partial dislocation in deformation twins decompose into perfect dislocation and Shockley partial dislocation under applied stress. These dislocations slip along crystal planes and react to form dislocation combinations that constitute the ITBs. The results provide researchers with a new perspective on the role of ITBs in deformation twinning and the formation of dislocation combinations in ITBs.
SCRIPTA MATERIALIA
(2022)
Article
Nanoscience & Nanotechnology
Xinyi Liu, Yipeng Li, Guang Ran, Yifan Ding, Xiuyin Huang
Summary: The evolution and dynamic behaviors of dislocation loops in tungsten under 30 keV H2+ irradiation at different temperatures were studied. The study revealed different types of dislocation loops with varying characteristics at different temperatures, shedding light on the effects of temperature on the formation and behavior of dislocation loops in irradiated tungsten.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Materials Science, Multidisciplinary
Xi Qiu, Hua Pang, Guang Ran, Yong Xin, Yipeng Li, Qing Han, Wenjie Li, Xiaoming Chai, Shixin Gao, Quan Li, Yuanming Li, Yongjun Jiao
Summary: In-situ TEM observation was conducted to study the loop evolution in Mo-5 wt.%Re alloy under 400 keV Fe+ irradiation at 700°C and 800°C. The initiation of loops was observed throughout the irradiation process. Changes in dislocation line behavior and loop habit plane were observed in-situ, and the merging of three loops was facilitated by an intermediate bridge. Three main mechanisms for loop disappearance were identified, including loop aggregation, absorption by strong defect sinks, and the influence of surrounding loops. The study also investigated the relationship between irradiation parameters and the formation and behavior of loops. The in-situ observation of microstructure evolution provides valuable insights into the irradiation damage behavior of Mo-Re alloy.
JOURNAL OF NUCLEAR MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
J. L. Du, H. Q. Chen, C. Xu, Y. Fan, Y. H. Qiu, H. Wang, E. G. Fu
Summary: The study focused on the mechanism of trapping and recombining irradiation induced defects at interfaces, investigating factors that determine the sink efficiency of an interface to irradiation induced defects.
Article
Materials Science, Ceramics
Ziqi Cao, Kun He, Guang Ran, Xi Qiu, Dan Sun, Yipeng Li, Yong Xin
Summary: This study investigates the influence of thermal effect on the microstructure of irradiated CeO2. Experimental results show that dislocation loops in irradiated CeO2 shrink or disappear as the annealing time increases. The shrinkage is more significant for smaller dislocation loops. In addition, when the loop size exceeds a certain threshold, the loop grows rapidly at the beginning of annealing and then remains stable.
CERAMICS INTERNATIONAL
(2022)
Article
Materials Science, Multidisciplinary
Chi Xu, Wentuo Han, Wenbin Xue, Yongliang Li, Song Li, Bingsheng Li, Farong Wan
Summary: The study observed in-situ dislocation motions in a single-crystalline gold thinfoil specimen driven by electron-beam illumination. Two types of dislocation motions were identified, with one leaving clear traces and the other leaving passage traces. The motions exhibit jerky behaviors and accelerate with increased beam intensity, leaving immobile trace structures identified as twin structures along the <111> crystal directions.
MATERIALS CHARACTERIZATION
(2022)
Article
Chemistry, Physical
C. Panetier, Y. Pipon, C. Gaillard, D. Mangin, J. Amodeo, J. Morthomas, T. Wiss, A. Benedetti, R. Ducher, R. Dubourg, N. Moncoffre
Summary: Experimental investigations and atomistic simulations are combined to study the cesium diffusion processes at high temperature in UO2. The influence of defect type and concentration on cesium diffusion process is identified, and the corresponding activation energy is determined.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Mariana M. Timm, Lucien Saviot, Aurelien Crut, Nicholas Blanchard, Lucian Roiban, Karine Masenelli-Varlot, Lucile Joly-Pottuz, Jeremie Margueritat
Summary: This paper presents the use of optical spectroscopy techniques to study the vibrational modes of single gold nanocrystals and their interactions with light. The results show that nanoparticle crystallinity has a significant impact on inelastic scattering spectra, and slight shape and environment effects can also modify the spectra.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Materials Science, Multidisciplinary
Qinqin Xu, Nicolas Salles, Jerome Chevalier, Jonathan Amodeo
Summary: In this study, the transferability of various interatomic potentials for aluminum oxide was investigated, with a focus on the material properties relevant to nanomechanical applications such as lattice properties, surface and stacking fault energies, and dislocation modeling. Simulation results were compared with DFT simulations and experimental data from the literature.
MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING
(2022)
Article
Materials Science, Multidisciplinary
Camille Maestre, Yangdi Li, Vincent Garnier, Philippe Steyer, Sebastien Roux, Alexandre Plaud, Annick Loiseau, Julien Barjon, Lei Ren, Cedric Robert, Bo Han, Xavier Marie, Catherine Journet, Berangere Toury
Summary: In the field of 2D materials, hexagonal boron nitride (hBN) stands out for its excellent characteristics including high thermal conductivity, low compressibility, and wide band gap. It holds great promise for applications in van der Waals heterostructures. Researchers have developed a method combining polymer derived ceramics (PDC) and pressure-controlled sintering (PCS) to obtain millimeter-scale hBN crystals with high chemical and crystalline quality. Exfoliated hBN crystals, known as boron nitride nanosheets (BNNSs), were used to encapsulate transition metal dichalcogenides (TMDs) in van der Waals heterostructures. Optical spectroscopy was used to test the quality and potential opto-electronic applications of these BNNSs.
Article
Materials Science, Ceramics
Omid Akhlaghi, Erik Camposilvan, Zahra Goharibajestani, Sirous Khabbaz Abkenar, Cleva W. Ow-Yang, Yves Jorand, Laurent Gremillard, Vincent Garnier, Jerome Chevalier
Summary: This work describes the development of transparent high-strength Yttria-Stabilized Zirconia (YSZ) ceramics with ultra-fine grain size. Utilizing conventional pressure-less densification, full densification and excellent light transmission were achieved. The resulting ceramics also exhibited high biaxial strength attributed to the refined microstructure and martensitic phase transformation.
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
(2022)
Article
Materials Science, Multidisciplinary
Marion Borde, Michel Freyss, Emeric Bourasseau, Bruno Michel, David Rodney, Jonathan Amodeo
Summary: In this study, the core structure and mobility of the 12 (110){001} edge dislocation in UO2 were investigated using atomistic simulations and ab initio calculations. A new dislocation core structure, called "zigzag," was discovered to be prevalent at high temperatures. The velocity of the dislocation was determined through simulations, and a dislocation mobility law was adjusted for the multi-scale modeling of UO2 nuclear fuel mechanical properties.
JOURNAL OF NUCLEAR MATERIALS
(2023)
Article
Materials Science, Ceramics
Mathilde Maillard, Jerome Chevalier, Laurent Gremillard, Guilhem P. Baeza, Edwin-Joffrey Courtial, Sarah Marion, Vincent Garnier
Summary: Robocasting, also known as Direct Ink Writing, is a method for creating dense ceramic parts using micro-extrusion of ceramic pastes through controlled 3D positioning of needles. The quality of the printed parts is influenced by the rheological properties of the ceramic pastes, printing parameters, and thermal post processes. This study characterizes the rheological properties of alumina pastes, establishes correlations between rheological properties and printing conditions, and evaluates extrudability, shape fidelity, and mechanical performance of the final parts. The paper introduces an extended definition of printability that considers functional requirements of the final parts in addition to processability criteria.
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
(2023)
Article
Materials Science, Ceramics
Qinqin Xu, Jerome Chevalier, Jonathan Amodeo
Summary: This study investigates the mechanical response and deformation mechanism of alpha-Al2O3 nanoparticles under compression using classical molecular dynamics simulations. The results show that these nanoparticles can withstand elevated force before yielding due to a surface nucleation process involving various dislocations and nanotwins, which are sensitive to orientation and temperature. The findings are explained in terms of stacking-fault energy and shear stress analysis and compared with recent micromechanical tests and observations in bulk materials.
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
(2023)
Article
Materials Science, Multidisciplinary
Javier Antonio Gonzalez Joa, Laurent Dupuy, Peter Raback, Marc Fivel, Michel Perez, Jonathan Amodeo
Summary: In this study, a new tool called El-Numodis is introduced, which combines the discrete dislocation dynamics code Numodis with the open-source finite-element modeling tool Elmer using the superposition method. This tool allows for the simulation of small-scale object deformation and mechanical properties, including various surface-related plastic deformation processes. The main features of the code, as well as numerical test cases ranging from classical boundary value problems to tensile tests on model thin film, are presented in this study.
MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING
(2023)
Article
Nanoscience & Nanotechnology
Hugo Iteney, Thomas W. Cornelius, Olivier Thomas, Jonathan Amodeo
Summary: The mechanics of nano-objects are strongly influenced by the experimental setup. This study introduces a new strategy of load-controlled molecular dynamics simulations to analyze nanoparticle compression. The results show that load-controlled simulations align better with experimental observations, and the evolution of dislocation microstructure is also investigated.
SCRIPTA MATERIALIA
(2023)
Article
Materials Science, Multidisciplinary
Ronan Madec, Luc Portelette, Bruno Michel, Jonathan Amodeo
Summary: The mechanical behavior of UO2 single crystal, especially the unexpected multi-slip observations, has been studied in this research. A multi-scale model based on composite slip is proposed, in which dislocation density can be transferred from primary slip systems to secondary systems under the effect of cross-slip. This approach accurately describes the anisotropic mechanical response of UO2 single crystal, providing new insights into the links between dislocation microstructures and mechanical properties. The composite slip mechanism appears to be a candidate for explaining unexpected plastic behaviors in complex materials with multiple slip modes, suggesting that slip activation may be more complex than in usual constitutive laws.
Article
Engineering, Mechanical
Marion Borde, Laurent Dupuy, Adrien Pivano, Bruno Michel, David Rodney, Jonathan Amodeo
Summary: In this study, the plasticity of irradiated UO2 is investigated using molecular dynamics and discrete dislocation dynamics simulations. The interactions between irradiation loops and glissile dislocations are studied, and the effects of these interactions on the strengthening of UO2 are characterized. The collective behavior of irradiation defects and the formation of clear bands in UO2 fuel at high temperature are also discussed.
INTERNATIONAL JOURNAL OF PLASTICITY
(2023)
Article
Materials Science, Multidisciplinary
Gaetan Laurens, Jonathan Amodeo, Tristan Albaret
Summary: The mechanical properties and elementary deformation processes of ceria nanoparticles are studied using quasi-static atomistic simulations. The results show that both stress response and plastic deformation are size-dependent. Smaller nanoparticles undergo amorphization and recrystallization processes from their surfaces, while larger nanoparticles exhibit the propagation of {111} nanotwins. The recrystallized phase is made of reoriented fluorite, which acts as a structural seed for the formation of nanotwins.
Article
Materials Science, Multidisciplinary
A. Schmitt, D. Mele, M. Rosticher, T. Taniguchi, K. Watanabe, C. Maestre, C. Journet, V. Garnier, G. Feve, J. M. Berroir, C. Voisin, B. Placais, E. Baudin
Article
Materials Science, Multidisciplinary
Djafar Iabbaden, Jonathan Amodeo, Claudio Fusco, Florence Garrelie, Jean-Philippe Colombier
Summary: This paper reports a theoretical simulation combining the two temperature model and classical molecular dynamics simulations to unravel the mechanisms that lead to the localized phase transition in Cu-Zr metallic glass. The initial composition of amorphous samples and nonequilibrium thermodynamic processes caused by laser energy deposition were found to play essential roles. It was further demonstrated that specific compositions devitrify despite their high glass-forming ability, and the thermodynamic conditions for stable nanocrystalline phase were established.
