Article
Materials Science, Multidisciplinary
O. V. Pshyk, X. Li, I. Petrov, D. G. Sangiovanni, J. Palisaitis, L. Hultman, G. Greczynski
Summary: Traditional age hardening mechanisms in refractory ceramics involve the precipitation of fine particles. In this study, Guinier-Preston zone hardening, previously known in soft light-metal alloys, was found to occur in refractory ceramics like multicomponent nitrides. The discovery of added superhardening in Ti-Al-W-N thin films upon high temperature annealing, due to the formation of W disks on {111} planes, offers a new approach for developing advanced materials with exceptional mechanical properties and wider operational temperature range for future applications.
Article
Nanoscience & Nanotechnology
Ling Ou, Lin-Yan Li, Fan-Cai He, Yu-Feng Nie, Shi-Chen Li
Summary: Using first-principles calculations, the energetics of Guinier-Preston zone (GPZ) formation in response to external strain in the Al-Cu system was systematically investigated. The results showed that when the applied strain exceeded a certain threshold, the precipitation of GPZ preferentially occurred parallel (perpendicular) to the direction of tensile (compressive) strain, and the precipitation energy of GPZ had a parabolic relationship with the magnitude of strain. The variation of precipitation energy was related to the misfit between GPZ and the matrix, which affected the number of bonding electrons below the Fermi level.
Article
Nanoscience & Nanotechnology
T. T. Sasaki, J. Y. Lin, P. Yi, Z. H. Li, S. E. Prameela, A. Park, E. Lipkin, A. Lee, M. L. Falk, T. P. Weihs, K. Hono
Summary: In this study, the deformation-induced precipitation of G.P. zones in Mg-9Al and Mg-5 Zn alloys during equal channel angular extrusion has been reported. Atom probe tomography and hybrid molecular dynamics/Monte Carlo simulations suggest that strategic control of atomic-scale defects can generate novel microstructures, thereby strengthening the deformed Mg alloys.
SCRIPTA MATERIALIA
(2022)
Article
Nanoscience & Nanotechnology
Heting Liao, Hajime Kimizuka, Akio Ishii, Jun-Ping Du, Shigenobu Ogata
Summary: In this study, the nucleation kinetics of β'' precipitates in Mg-3.0 at.%Y system were explored using kinetic Monte Carlo approach. Results showed an optimum temperature of 550 K for the formation of β'' precipitates and an upper temperature limit of 700 K.
SCRIPTA MATERIALIA
(2022)
Article
Multidisciplinary Sciences
Hiroshi Miyoshi, Hajime Kimizuka, Akio Ishii, Shigenobu Ogata
Summary: The study evaluated the precipitation process of GP zones in Al-Cu alloys, proposing a nucleation theory model for different zone types (GP1 and GP2) that aligns with experimental observations. The results illustrate the competing nucleation mechanisms between GP1 and GP2, providing guidance for tailoring aging conditions to achieve desired mechanical properties for specific applications.
SCIENTIFIC REPORTS
(2021)
Article
Quantum Science & Technology
Matija Medvidovic, Giuseppe Carleo
Summary: In this study, a new method is introduced to simulate layered quantum circuits using a neural network parametrization, allowing for accurate Quantum Approximate Optimization Algorithm (QAOA) simulations with smaller computational resources.
NPJ QUANTUM INFORMATION
(2021)
Article
Materials Science, Multidisciplinary
Guillaume Hachet, Xavier Sauvage
Summary: The influence of hydrogen on the formation and growth of GP zones during natural ageing in an Al-5Cu alloy was investigated experimentally and numerically. The experimental observations showed that the presence of hydrogen slows down the growth of GP zones, resulting in delayed hardening. Ab initio calculations revealed that hydrogen trapped in vacancies significantly reduces the diffusion coefficient of copper and the self diffusion of aluminium, leading to the delayed hardening.
Article
Materials Science, Multidisciplinary
Chao Jiang, Yongfeng Zhang, Larry K. Aagesen, Andrea M. Jokisaari, Cheng Sun, Jian Gan
Summary: Understanding the interactions of noble gases with metals is crucial for designing radiation-resistant structural materials for nuclear reactors. A unified theory has been proposed to describe the energetics of noble gas bubbles in various bcc metals, revealing the exceptional thermal stability of Ne, Ar, and Kr bubbles compared to He bubbles. The study provides new insights on the stability of fission gas bubble superlattice in bcc U-Mo and shows good agreement with existing thermal helium desorption spectrometry experiments.
Article
Chemistry, Physical
Heting Liao, Hajime Kimizuka, Hiroshi Miyoshi, Shigenobu Ogata
Summary: In this study, the nucleation preference of coherent GP zones and semicoherent theta' nanoprecipitates in Al-Cu alloys were characterized using classical nucleation theory (CNT) and a machine-learning-based interatomic potential. The findings revealed the temperature and solute-concentration dependencies of the nucleation barriers of the nanoprecipitates, which determine the crossover temperatures for the formation of each precipitate. The predicted results were in good agreement with previous experimental observations. This study contributes to the understanding of nucleation forces in Al-Cu alloys and provides theoretical guidance for the optimal age-hardening response.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Materials Science, Multidisciplinary
J. Lepinoux
Summary: This paper explores three methods for studying the evolution of critical size with time from nucleation to coarsening, using precipitation in concentrated AlLi alloys as a model case.
PHILOSOPHICAL MAGAZINE
(2022)
Article
Materials Science, Multidisciplinary
Kazushi Aoyama, Masaki Gen, Hikaru Kawamura
Summary: The study found that the 12 plateau appears in the magnetization curve in both models, being relatively robust against breathing bond alternation, but magnetic long-range orders are only realized in the site-phonon model. The nature characteristic of the breathing pyrochlore lattice leads to the occurrence of unconventional phases based on tetrahedra units.
Article
Chemistry, Physical
Hung Ba Tran, Tetsuya Fukushima, Hiroyoshi Momida, Kazunori Sato, Yukihiro Makino, Tamio Oguchi
Summary: The magnetocaloric effects of FeRh alloy, including both direct and inverse effects, have been studied using first-principles calculations and Monte Carlo simulations. The research successfully reproduces experimental results and reveals that FeRh alloy has a giant relative cooling power due to its large saturation magnetizations and first-order antiferromagnetic-ferromagnetic phase transition.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Astronomy & Astrophysics
Eric R. Anschuetz, Lena Funcke, Patrick T. Komiske, Serhii Kryhin, Jesse Thaler
Summary: This paper introduces a method to enhance the performance of annealing algorithms by using degeneracy engineering, illustrated through the example of l(0)-norm regularization for sparse linear regression. The results show that degeneracy engineering substantially improves the annealing performance, motivating its application to various regularized optimization problems.
Article
Materials Science, Multidisciplinary
Hung Ba Tran, Hiroyoshi Momida, Yu-ichiro Matsushita, Koun Shirai, Tamio Oguchi
Summary: This study investigates the temperature dependence of magnetocrystalline anisotropy energy in CrI3 and its effect on the thermodynamic properties. The research successfully reproduces the negative sign of the isothermal magnetic entropy changes and reveals the role of anisotropic magnetic susceptibility and magnetization anisotropy. The findings shed light on the connection between magnetic field direction, entropy change, and free energy difference in CrI3.
Article
Chemistry, Physical
Hung Ba Tran, Tetsuya Fukushima, Kazunori Sato, Yukihiro Makino, Tamio Oguchi
Summary: The study proposed a new model and scheme to investigate the magnetocaloric properties of Mn1-xCuxCoGe alloy, and found that the enhancement of magnetostructural coupling significantly affects the isothermal magnetic entropy change, depending on the conditions of magnetic phase transition temperatures.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Chemistry, Multidisciplinary
Si-Mian Liu, Akio Ishii, Shao-Bo Mi, Shigenobu Ogata, Ju Li, Wei-Zhong Han
Summary: The growth of hydrides is a hybrid displacive-diffusive process regulated by intermittent dislocation emissions. The tensile stress field around the hydride affects the solubility of hydrogen in the Zr matrix, which in turn influences hydride growth and precipitation. The emission of dislocations mediates hydride growth and leads to the formation of butterfly or bird-nest configurations around the hydride.
Article
Metallurgy & Metallurgical Engineering
Akihiro Mitsuhara, Hiroshi Yukawa, Hajime Kimizuka
Summary: In this study, the effects of excess Cu atoms on the hydrogen permeability of Pd-Cu alloys were investigated. It was found that reducing the excess Cu atoms can improve the hydrogen solubility, but no significant differences in hydrogen diffusivity were observed due to the presence of excess Cu atoms. These findings provide a basis for enhancing the hydrogen permeability of Pd-Cu alloys.
JOURNAL OF THE JAPAN INSTITUTE OF METALS AND MATERIALS
(2022)
Article
Energy & Fuels
Hajime Kimizuka, Bo Thomsen, Motoyuki Shiga
Summary: This study investigates the contribution of nuclear quantum effects (NQEs) to the kinetics and dynamics of interstitial H isotopes in face-centered cubic Pd using various path-integral techniques and a machine-learning interatomic potential. The results demonstrate the importance of NQEs even at high temperatures, highlighting the characteristic temperature dependence of activation free energies for H-isotope migration in Pd. The study also compares different quantum-dynamics methods and shows that the results obtained using centroid molecular dynamics (CMD) and ring-polymer molecular dynamics (RPMD) are more consistent with experimental values than those obtained using quantum transition-state theory.
JOURNAL OF PHYSICS-ENERGY
(2022)
Article
Materials Science, Multidisciplinary
Hyukjoon Kwon, Motoyuki Shiga, Hajime Kimizuka, Takuji Oda
Summary: The diffusion of hydrogen in metals is difficult to accurately measure due to surface and trapping effects, resulting in large deviations in reported experimental data. Computational studies have proposed atomistic simulation methods, but their accuracy remains questionable. This study used machine-learning moment tensor potentials with the accuracy of density functional theory to estimate the diffusivity of hydrogen in three bcc metals. The calculations showed excellent agreement with experimental data in the appropriate temperature range.
Article
Materials Science, Multidisciplinary
Akio Ishii
Summary: The existence of the B33 phase in TiNi alloys, which was considered stable using density functional theory calculations but not experimentally confirmed, is controversial. This study investigated the existence of the B33 phase in the TiNi shape memory alloy using Eshelby's ellipsoidal inclusion method informed by density functional theory calculations. The calculated total strains of the heterogeneously nucleated B33 phase were similar to the eigenstrains of the B19' phase, indicating an elastic suppression of the B33 phase and its transformation to the B19' phase by the original B2 matrix. The elastic inhomogeneity between the B2 matrix and B33 phase was confirmed to play a role in this transformation process.
COMPUTATIONAL MATERIALS SCIENCE
(2023)
Article
Nanoscience & Nanotechnology
Hongxian Xie, Gaobing Wei, Jun-Ping Du, Akio Ishii, Guanghong Lu, Peijun Yu, Shigenobu Ogata
Summary: This study examined the anti-twinning and deformation twinning of body-centered-cubic metals under shear loading. It found a novel two-layer-by-two-layer anti-twinning mechanism that generates finite shear displacement along specific atomic planes. The newly observed anti-twinning process has a lower energy barrier for twin nucleation and growth compared to the previously proposed layer-by-layer anti-twinning process.
SCRIPTA MATERIALIA
(2023)
Article
Chemistry, Physical
Heting Liao, Hajime Kimizuka, Hiroshi Miyoshi, Shigenobu Ogata
Summary: In this study, the nucleation preference of coherent GP zones and semicoherent theta' nanoprecipitates in Al-Cu alloys were characterized using classical nucleation theory (CNT) and a machine-learning-based interatomic potential. The findings revealed the temperature and solute-concentration dependencies of the nucleation barriers of the nanoprecipitates, which determine the crossover temperatures for the formation of each precipitate. The predicted results were in good agreement with previous experimental observations. This study contributes to the understanding of nucleation forces in Al-Cu alloys and provides theoretical guidance for the optimal age-hardening response.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Materials Science, Multidisciplinary
Rana Hossain, Hajime Kimizuka, Shigenobu Ogata
Summary: MAX phases are a unique class of atomically layered ceramics that deform plastically at room temperature due to highly mobile basal dislocations (BDs). In this study, a machine-learning-based spectral neighbor analysis potential (SNAP) was developed to simulate the edge, screw, and mixed BDs in a Ti3SiC2 MAX phase. The SNAP calculations reveal that the BD core structure exhibits significant asymmetry depending on the position of the weakly bonded Si layer. Undissociated BD cores are centered on Si layers and have lower mobility compared to partial BDs. The findings contribute to a deeper understanding of the atomic-level behavior of BDs and the deformation modes of crystals with layered structures.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Akio Ishii
Summary: In this study, we predicted the temperature-dependent stability of the heterogeneous B19' phase in the B2 matrix of TiNi alloys using DFT and phonon analysis. The eigenstrains and elastic constants of Eshelby's ellipsoidal inclusion were calculated under a quasi-harmonic approximation. The orientation and total strains of the disk-shaped B19' phase in the B2 matrix were evaluated with respect to temperature using Eshelby's ellipsoidal inclusion analysis. By comparing the temperature-dependent free energies of the B2 and elastically deformed B19' structures, the transformation between the two phases was successfully predicted to occur at 300 K, in agreement with experiments. The temperature-dependent difference in elastic constants between the B19' phase and B2 matrix was shown to influence the phase transformation, which is the origin of the shape-memory effect of TiNi alloy.
MATERIALS TODAY COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Hiroshi Okuda, Kohei Kintsu, Shu Kurokawa, Masao Tabuchi, Hiroaki Nitani, Hajime Kimizuka, Shin-ichi Inoue, Michiaki Yamasaki, Yoshihito Kawamura
Summary: A coarse-grained picture of segregation layers in MgYZn alloys has been confirmed, where the layers are two-dimensional cluster systems bound in stacking faults. The use of EXAFS, small-angle X-ray scattering, and scanning tunneling microscopy showed that the atomic configurations around Y and Zn atoms in the segregation layers are identical, indicating the presence of L12 clusters. This fingerprint was observed in both bulk LPSO structures and dilute MgYZn alloys.
Article
Physics, Applied
N. Nakamura, K. Matsuura, A. Ishii
Summary: In this study, the formation process of Pd-based bimetallic nanoparticles synthesized by co-sputtering was investigated using in situ morphological observation and molecular dynamics analysis. It was found that the metal with lower surface energy segregates on the nanoparticle surface, and the formation process of alloy nanoparticles tends to be similar to that of nanoparticles composed of the core metal, regardless of the atomic fraction of the shell metal.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Nobutomo Nakamura, Koji Matsuura, Akio Ishii, Hirotsugu Ogi
Summary: The formation process of core-shell bimetallic nanoparticles synthesized by sputtering onto a substrate was observed in real time using an acoustic technique. The experiments revealed that restructuring occurred in the Pd-Au alloy system, resulting in the formation of A-shell/B-core nanoparticles, while other systems tended to form B-shell/A-core nanoparticles.
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.