Article
Materials Science, Multidisciplinary
Giacomo Po, Yue Huang, Yang Li, Kristopher Baker, Benjamin Ramirez Flores, Thomas Black, James Hollenbeck, Nasr Ghoniem
Summary: This article develops a framework to investigate thermal creep and annealing in finite domains by coupling the climb motion of discrete dislocations with the diffusion of a continuum vacancy field. It formulates a model using irreversible thermodynamics and linearizes it for implementation in three-dimensional discrete dislocation dynamics simulations. The framework includes both diffusional creep and dislocation creep, and is applied to simulate annealing and estimate creep rate in various materials under different conditions.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2022)
Article
Materials Science, Multidisciplinary
Yang Li, Nasr Ghoniem, Kristopher Baker, Benjamin Ramirez Flores, Thomas Black, James Hollenbeck, Giacomo Po
Summary: We propose a novel model to study the climb/glide motion of jogged screw dislocations within the discrete dislocation dynamics (DDD) framework. We show that the model predictions are consistent with experimental data in both gamma-TiAl and Zircaloy-4. Based on simulations and a detailed examination of the predicted jog heights, we advance the hypothesis that a combination of jog dragging and dipole bypass mechanisms is necessary to reproduce the high creep rate observed in some experiments.
Article
Materials Science, Multidisciplinary
D. Da Fonseca, F. Onimus, F. Mompiou, M. -C. Marinica, E. de Sonis, E. Clouet, T. Jourdan
Summary: This study investigates the influence of elastic properties of point defects on dislocation climb under stress and irradiation. The elastic dipole tensors and diaelastic polarizabilities of vacancies and self-interstitial atoms in aluminum are evaluated using density functional theory calculations. These parameters are then incorporated into a Monte Carlo code and a diffusion model to estimate the stress dependence of dislocation climb. The results show that both parameters have an influence on point defect absorption under stress, with the dipole tensor effect only being 5 times larger than the polarizability effect. Additionally, considering polarizability is necessary for simulations under applied stress.
Article
Materials Science, Ceramics
Hojun Lee, Si Yeon Kim, Young-In Lee, Jongmin Byun
Summary: This study verifies the advantages of synthesizing Ti-Al-C MAX phases using intermetallic compounds instead of elemental powders. Diffusion experiments show that Ti2AlC is produced at 1000 degrees C and Ti3AlC2 at 1300 degrees C when intermetallic compounds are used, while Ti2AlC is produced at 1300 degrees C and Ti3AlC2 at 1400 degrees C when using elemental powder. Heat treatment at 1400 degrees C for 3 hours decreases Ti3AlC2 content and increases Ti2AlC when elemental powder is used, but increases Ti3AlC2 content when intermetallic compounds are used.
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
(2023)
Article
Engineering, Mechanical
Chutian Huang, Shuyang Dai, Xiaohua Niu, Tianpeng Jiang, Zhijian Yang, Yejun Gu, Yang Xiang
Summary: This paper presents a continuum formulation for dislocation climb velocity based on densities of dislocations, which is an accurate approximation of the Green's function-based discrete dislocation dynamics method. The continuum dislocation climb formulation has the advantage of accounting for both the long-range effect of vacancy bulk diffusion and that of the Peach-Koehler climb force, and simplifies the calculation process in the Green's function-based discrete dislocation dynamics method. The obtained continuum dislocation climb velocity can be applied in any available continuum dislocation dynamics frameworks.
INTERNATIONAL JOURNAL OF PLASTICITY
(2023)
Article
Chemistry, Physical
Y. Dong, L. Y. Ye, X. D. Liu, B. Ke, T. J. Hu
Summary: The study investigated the creep-aging behaviors and mechanical properties of Al-Cu-Li alloys with different grain sizes. It was found that creep strains increase with increasing grain size, while yield and tensile strengths are grain size independent.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Materials Science, Multidisciplinary
Nagarajan Thiyaneshwaran, Chithirai Pon Selvan, Avinash Lakshmikanthan, Katakam Sivaprasad, Balasubramanian Ravisankar
Summary: This study compares Ti/Al and Ti/Ni metal intermetallic laminates (MILs) and finds that both have specific strength, but Ti/Al MILs have lower density values than Ti/Ni laminates.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2021)
Article
Nanoscience & Nanotechnology
Qiang Yang, Zixiang Yan, Shuhui Lv, Kai Guan, Xin Qiu
Summary: Abnormal creep stress exponents were reported for heat-resistant magnesium alloys without detailed explanation on underlying creep mechanisms. The study on a Mg-3.76Al-3.52RE-0.23Mn alloy showed varying n-values at different stresses, with microstructural analysis suggesting changes in dominant creep mechanisms. Introducing threshold stress and internal stress helped rationalize the abnormal n-values, providing insights for improving creep resistance in magnesium alloys.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Multidisciplinary Sciences
Thomas Breithaupt, Richard F. Katz, Lars N. Hansen, Kathryn M. Kumamoto
Summary: In applications critical to the geological, materials, and engineering sciences, deformation occurs at strain rates too small to be accessed experimentally. Empirical relationships are used to make predictions, but this leads to uncertainties. To address this, a theory of dislocation processes is constructed and validated for olivine deformation. The model explains strain rate, applied stress, and dislocation density relationships, and predicts rapid transient deformation in the upper mantle under Earth conditions.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2023)
Article
Multidisciplinary Sciences
Shufen Chu, Pan Liu, Yin Zhang, Xiaodong Wang, Shuangxi Song, Ting Zhu, Ze Zhang, Xiaodong Han, Baode Sun, Mingwei Chen
Summary: In this study, the authors report real-time atomic-scale observations of grain boundary dislocation climb in nanostructured gold at room temperature. The climb of a dislocation is found to occur through stress-induced reconstruction of neighboring atomic columns. The proposed atomic route of dislocation climb is energetically favorable, as demonstrated by Monte Carlo simulations. The in situ observations also reveal the significance of grain boundary dislocation climb in controlling the microstructures and properties of nanostructured metals.
NATURE COMMUNICATIONS
(2022)
Article
Nanoscience & Nanotechnology
Xi Wang, Qi Rong, Zhusheng Shi, Yong Li, Junxia Cao, Baoguo Chen, Jianguo Lin
Summary: The creep-ageing behavior of a 2xxx series 3rd generation Al-Li alloy in T8 state was experimentally investigated under different stresses, showing significant differences in creep strain with increasing stress levels. The dominant deformation mechanism shifted from diffusion creep to dislocation creep at higher stresses, revealing a strong stress dependent characteristic in creep deformation and evolution of dislocation density and precipitate size during creep-ageing.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Physics, Multidisciplinary
Esko Toivonen, Matti Molkkari, Esa Rasanen, Lasse Laurson
Summary: Under the symmetry breaking caused by the direction of the driving force, the roughness of elastic interfaces exhibits asymmetry, which can be quantified by computing the spectrum of local scaling exponents.
PHYSICAL REVIEW LETTERS
(2022)
Article
Engineering, Mechanical
Cameron McElfresh, Yinan Cui, Sergei L. Dudarev, Giacomo Po, Jaime Marian
Summary: Dislocation climb, a crucial high-temperature process in metal plasticity, is controlled by point defect diffusion and thermal activation. A new kinetic Monte Carlo model has been developed to study vacancy generation and transport kinetics in conjunction with evolving elastic fields, revealing surprising results such as dominance of vacancy emission in climb and faster climb velocities than expected. This discrete approach offers insights not captured by classical theories based on smooth vacancy fluxes.
INTERNATIONAL JOURNAL OF PLASTICITY
(2021)
Article
Materials Science, Multidisciplinary
Jovid U. Rakhmonov, Sumit Bahl, Amit Shyam, David C. Dunand
Summary: The study found that the RR350 alloy has better creep resistance than the ACMZ alloy at low stresses due to a higher amount of intergranular precipitates and fewer precipitate-free zones near grain boundaries. At high stresses, compressive creep is controlled by dislocation creep, while tensile creep is influenced by cavitation at intergranular precipitates.
Article
Materials Science, Multidisciplinary
Saif Haider Kayani, Min Cui, Rana Tariq Mehmood Ahmed, Young -Hee Cho, Jung-Moo Lee, Nho-Kwang Park, Hafiz Muhammad Salman Ajmal, Kwangjun Euh
Summary: The mechanism of pore formation associated with intermetallic reaction in sintered Ti50Al50 alloy was studied using two different heating rates, 1°C/min and 10°C/min. The heating rate had a significant effect on pore parameters and intermetallic reactions. Pore size and porosity increased with the extent of exothermic reactions during sintering. Different intermetallic phases formed at different temperatures due to reaction between Ti2Al5 phase, Al, and Ti. The higher heating rate of 10°C/min resulted in considerable changes in thermal and volume expansion compared to 1°C/min. Thus, the heating rate during sintering greatly influenced the porous properties of Ti50Al50 by controlling the degree of exothermic reactions.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2023)
Article
Chemistry, Applied
Juan Martin-Gomez, Juan Carlos Escamilla, Jesus Hidalgo-Carrillo, Francisco J. Loprez-Tenllado, Rafael C. Estevez-Toledano, M. Carmen Herrera-Beurnio, Miguel Castillo-Rodriguez, Francisco J. Urbano, Alberto Marinas
Summary: Titanium dispersed on carbonaceous mesoporous support was modified with copper via photodeposition using glycerol or methanol as the sacrificial agent. The synthesized catalysts were tested in glycerol photoreforming reaction, and it was found that copper photodeposition increased the activity compared to titania-mesoporous carbon composite. However, copper in glycerol-based catalyst redispersed during reaction, exhibiting similar activity to methanol-based catalyst after one use. Strong adsorption of reaction intermediates also contributed to catalyst deactivation, as revealed by competitive reactions with glycolic and glyceric acid.
Article
Thermodynamics
M. Morawiec, J. Opara, C. Garcia-Mateo, J. A. Jimenez, A. Grajcar
Summary: This work provides insights into the influence of manganese on the driving force and kinetics of bainite transformation. The study shows that increasing manganese content leads to a lower fraction of bainite formed during the isothermal stage and longer incubation and transformation time.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2023)
Article
Chemistry, Physical
Mikel Perez-Cerrato, Itziar Fraile, Jose Fernando Gomez-Cortes, Ernesto Urionabarrenetxea, Isabel Ruiz-Larrea, Iban Gonzalez, Maria Luisa No, Nerea Burgos, Jose M. San Juan
Summary: This study investigates the application of laser powder bed fusion and hot isostatic pressing in Cu-Al-Ni SMAs. It is found that a post-processing thermal treatment to control the microstructure is crucial for obtaining the expected functional properties. By using a designed processing route, satisfactory shape memory behavior can be achieved in Cu-Al-Ni SMAs.
Article
Materials Science, Multidisciplinary
Adriana Eres-Castellanos, Ana Santana, Luis Miguel Sanz-Moral, Rosalia Rementeria, Rebeca Hernandez Pascual, Marta Serrano, Isaac Toda-Caraballo, Jose A. Jimenez, Francisca G. Caballero, Carlos Capdevila
Summary: This study evaluated the effects of adding TiC nanoparticles on the microstructure and high temperature behavior of Grade 316 L stainless steel. The results showed that TiC nanoparticle inoculation did not alter the solidification structure and grain size, but it did modify the material's texture. Additionally, dispersion hardening improved the ductility, yield strength, and ultimate tensile strength of 316 L steel at high temperature.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2022)
Article
Chemistry, Applied
M. Carmen Herrera-Beurnio, Francisco J. Lopez-Tenllado, Jesus Hidalgo-Carrillo, Juan Martin-Gomez, Rafael Estevez, Miguel Castillo-Rodriguez, Gustavo de Miguel, Francisco J. Urbano, Alberto Marinas
Summary: Platinum was deposited on g-C3N4-TiO2 systems using UV or Vis light, and the resulting particle size and distribution were influenced by the absorption properties of the semiconductors. Smaller platinum particles were obtained on g-C3N4 under visible light and on TiO2 under UV radiation. The preferential deposition of platinum on g-C3N4 or TiO2 was observed, especially in physical mixtures of both semiconductors, depending on the radiation source. The solids showed enhanced hydrogen photoproduction activity under visible light, compared to physical mixtures or simultaneous incorporation of platinum.
Article
Materials Science, Multidisciplinary
Leticia Cabrera-Correa, Leandro Gonzalez-Rovira, Juan de Dios Lopez-Castro, Miguel Castillo-Rodriguez, F. Javier Botana
Summary: The mechanical properties and microstructure of Scalmalloy processed by SLM are studied. Two types of samples, as-built and heat-treated, are considered. Heat treatment does not affect grain size or texture. SEM images reveal a bi-modal microstructure with fine-grained and coarse-grained zones. EBSD analysis shows a reduction in grain boundaries, grain orientation spread, and dislocation density after heat treatment, leading to increased strength and hardness.
MATERIALS CHARACTERIZATION
(2023)
Article
Chemistry, Physical
Dolores G. Gil-Gavilan, Daniel Cosano, Miguel Castillo-Rodriguez, Gustavo de Miguel, Dolores Esquivel, Cesar Jimenez-Sanchidrian, Jose R. Ruiz, Francisco J. Romero-Salguero
Summary: Hydrogen is being extensively studied as one of the main future energy sources, and efforts are being made to directly convert solar energy into H-2. Hydrotalcites, a type of two-dimensional material, have shown potential for the H-2 evolution reaction when used alone or in combination with other materials. This study focused on preparing composites of Co-Al hydrotalcite with carbon spheres or nanotubes and found that such composites generally improve H-2 production. The nature, structure, and characteristics of the different materials, as well as the role and mechanism of each component, were investigated.
APPLIED CLAY SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
Adam Skowronek, Adam Grajcar, Carlos Garcia-Mateo, Jose A. Jimenez, Roumen H. Petrov
Summary: The present study explores the possibility of using continuous annealing approach in Al-alloyed 5Mn steel to optimize the superior mechanical properties in medium-Mn. The microstructural changes as a function of time were followed by dilatometric studies at 680 oC with different soaking times, and thoroughly characterized using various techniques. It was observed that with increasing soaking times, the volume fraction of retained austenite gradually increases, but at the cost of its stability. Mechanical tests results showed a decrease in yield stress, tensile strength and hardness with increasing intercritical annealing soaking time.
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
(2023)
Article
Chemistry, Applied
Raul Rojas-Luna, Juan Amaro-Gahete, Dolores G. Gil-Gavilan, Miguel Castillo-Rodriguez, Cesar Jimenez-Sanchidrian, Jose Rafael Ruiz, Dolores Esquivel, Francisco Jose Romero-Salguero
Summary: A new heterogeneous photosensitizer, Ru@dpdhpzBASF-A520, was successfully synthesized through a unique strategy incorporating dipyridyl-dihydropyridazine adducts onto the aluminum fumarate units of highly porous MOF BASF-A520 and coordinating them to ruthenium metal centers. The resulting material displayed strong visible light absorption, allowing it to function as a single-site solid photosensitizer for hydrogen evolution in a photochemical reaction. Through various characterization techniques, it was confirmed that the ruthenium dipyridyl-dihydropyridazine adducts were effectively stabilized on the MOF surface and could efficiently inject electrons to Pt nanoparticles mediated by MV electron carrier for hydrogen generation from water.
MICROPOROUS AND MESOPOROUS MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Daniel Carrasco, Eva Nieto-Pinero, Manuel Alonso-Orts, Rosalia Serna, Jose M. San Juan, Maria L. No, Jani Jesenovec, John S. S. McCloy, Emilio Nogales, Bianchi Mendez
Summary: An accurate understanding of the optical properties of beta-Ga2O3 is crucial for its full potential in photonics applications, especially its dependence on temperature. Optical micro- and nanocavities created within microwires and nanowires using distributed Bragg reflectors (DBR) show promise for various applications. This study analyzed the effect of temperature on the anisotropic refractive index of beta-Ga2O3 using ellipsometry, obtaining temperature-dependent dispersion relations fitted to Sellmeier formalism. Micro-photoluminescence (mu-PL) spectroscopy of microcavities in Cr-doped beta-Ga2O3 nanowires showed a thermal shift in red-infrared Fabry-Perot optical resonances, mainly due to temperature variations in the refractive index. Comparisons with finite-difference time-domain (FDTD) simulations incorporating the temperature-dependent, anisotropic refractive index obtained from ellipsometry revealed similar shifts, with slightly larger values observed in mu-PL results. The thermo-optic coefficient was calculated.
Article
Nanoscience & Nanotechnology
Jose F. Gomez-Cortes, Pawel Czaja, Maria L. No, Maciej J. Szczerba, Jose M. San Juan
Summary: This study investigates the stress-induced martensitic transformation in Ni51Mn28Ga21 shape memory alloy at the nanoscale, demonstrating a fully reversible behavior and outstanding stability of superelasticity during nano-compression tests on micropillars. Furthermore, the micropillars exhibit ultra-high strength and a noticeable size effect on the stress-induced martensite strength, which contributes to the good superelastic cycling behavior. These findings provide new potential applications for magnetic shape memory alloys in small-scale devices.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Chemistry, Physical
Dolores G. Gil-Gavilan, Daniel Cosano, Juan Amaro-Gahete, Miguel Castillo-Rodriguez, Dolores Esquivel, Jose R. Ruiz, Francisco J. Romero-Salguero
Summary: This study investigates the photocatalytic CO2 reduction reaction using zinc-chromium layered double hydroxides (LDHs) as catalysts under visible light irradiation. The influence of interlayer inorganic and organic anions and the metal ratio on the catalytic activity is studied. LDH3-SDC exhibits the best catalytic performance among the materials tested.
Article
Chemistry, Multidisciplinary
Jose F. Gomez-Cortes, Maria L. No, Andrey Chuvilin, Isabel Ruiz-Larrea, Jose M. San Juan
Summary: Cu-Al-Ni is a high-temperature shape memory alloy (HTSMA) that exhibits exceptional thermomechanical properties and is suitable for high-temperature MEMS/NEMS technologies. Recent studies have shown that this alloy has robust superelastic behavior at the nanometer scale, making it a good choice for developing new generations of micro-/nano-electromechanical systems. The experimental results indicate that the Cu-Al-Ni thin films produced by solid-state diffusion have high thermal stability, which is suitable for the development of high-temperature MEMS/NEMS.
Article
Materials Science, Multidisciplinary
Maria L. No, Thomas Klein, Helmut Clemens, Jose M. San Juan
Summary: This study provides a comprehensive investigation on the microstructure evolution of Nano-lamellar advanced gamma-TiAl based alloys using electron microscopy techniques. The results show that the precipitation of beta o and zeta phases delays the coarsening of the gamma lamellae, contributing to the enhanced creep resistance of the alloy.
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.
