Article
Chemistry, Multidisciplinary
Larissa Q. Huston, Alois Lugstein, Guoyin Shen, David A. Cullen, Bianca Haberl, Jim S. Williams, Jodie E. Bradby
Summary: High-pressure synthesis can create promising silicon allotropes, some of which have direct band gaps under tensile strain while others have narrow band gaps and good absorption properties. This study has discovered a new pressure-temperature pathway for producing silicon nanowires with transformative properties, opening up new possibilities for nanomaterial synthesis.
Article
Materials Science, Multidisciplinary
R. V. Sundeev, A. V. Shalimova, S. O. Rogachev, O. P. Chernogorova, A. M. Glezer, A. V. Ovcharov, I. A. Karateev
Summary: This study investigates the possibility of forming a multi-metal composite by high-pressure torsion (HPT) at room temperature using two dissimilar alloys, Ti50Ni25Cu25 and Fe50Ni33B17. The results show that the consolidation of the dissimilar layers is achieved through mutual severe plastic deformation.
Article
Nanoscience & Nanotechnology
Praveen Sathiyamoorthi, Peyman Asghari-Rad, Gangaraju Manogna Karthik, Alireza Zargaran, Hyoung Seop Kim
Summary: Fe40Mn40Co10Cr10 twinning induced plasticity high-entropy alloy processed by high-pressure torsion shows no typical grain refinement, but retains original grain size with the formation of strain-induced HCP martensitic phase.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Nanoscience & Nanotechnology
Subhasis Sinha, Vivek K. Sahu, Vikrant Beura, Reshma Sonkusare, Rajib Kalsar, Aman K. L. Das, Joysurya Basu, Nilesh P. Gurao, Krishanu Biswas
Summary: This study investigated the influence of initial texture on the deformation behavior of titanium under high pressure torsion. Results showed that the formation of the omega phase increased with strain, with different volume fractions depending on the initial texture orientation. The mechanical response, as measured by micro-hardness, was found to be dependent on the distribution of the omega phase, grain size, and strain component contributions. Synchrotron XRD measurements indicated that the crystallographic orientation relationships of omega transformation influenced the distribution of omega phase and strain partitioning, resulting in a texture-dependent hardness response.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Chemistry, Physical
Murillo Romero da Silva, Piter Gargarella, Athos Henrique Plaine, Josephine Zeisig, Simon Pauly, Uta Kuehn, Claudemiro Bolfarini
Summary: In this study, the Ti-29Nb-13Ta-4.6Zr-0.070 (TNTZO) alloy was processed by high-pressure torsion (HPT) and its microstructure, phase stability, elastic behavior, mechanical properties, and deformation mechanisms were investigated. An increase in beta-phase stability, significant hardening, and a new reverse martensitic transformation mechanism were observed after severe plastic deformation. The greater hardness was attributed to microstructural refinement, high dislocation density, and stress-induced formation of the omega-phase.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Chemistry, Physical
Robert Chulist, Aurimas Pukenas, Paul Chekhonin, Anton Hohenwarter, Reinhard Pippan, Norbert Schell, Werner Skrotzki
Summary: In this study, the forward and reverse phase transformation in the equiatomic high-entropy alloy CrMnFeCoNi were investigated using high-energy synchrotron radiation diffraction. The results showed that the phase transformation was influenced by hydrostatic pressure and shear stresses. The transformation affected the microstructure, texture, and microhardness of the alloy.
Article
Nanoscience & Nanotechnology
Olavo C. Haase, Paulo R. Cetlin, Roberto B. Figueiredo, Terence G. Langdon, Pedro Henrique R. Pereira
Summary: Processing by high-pressure torsion (HPT) was used to synthesize a high-strength nanocomposite from a mixture of Al and Cu powders. The consolidation and redistribution of second phases resulted in the stretching and fragmentation of Cu domains, leading to a more uniform distribution of Cu fragments. After 30 HPT revolutions, the composite exhibited a homogenous distribution of Cu fragments without any visible microcavities, indicating successful consolidation.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Materials Science, Multidisciplinary
Miao Song, Jens Darsell, Saumyadeep Jana
Summary: The effect of severe plastic deformation applied through friction extrusion method on an Al-Ti composite billet is summarized. The formation of layered amorphous regions and specific atomic ratios of Ti/Al, as well as the presence of crystalline Al-Ti intermetallic compounds and TiAl3 and TiAl forming et al./Ti interfaces, are observed. The thermal stability of the Al-Ti amorphous layered structures is also demonstrated during semi-in situ heating.
JOURNAL OF MATERIALS SCIENCE
(2022)
Article
Nanoscience & Nanotechnology
Faezeh Javadzadeh Kalahroudi, Hamidreza Koohdar, Terence G. Langdon, Mahmoud Nili-Ahmadabadi
Summary: Experiments conducted on an Fe-10Ni-7Mn martensitic steel processed by HPT showed a phase transformation from austenite to alpha'-martensite, with significant reduction in grain sizes and increase in hardness and ultimate tensile strength. Fracture surfaces after HPT processing exhibited a transition in fracture behavior from ductile to a mixture of ductile and brittle modes.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Nanoscience & Nanotechnology
Jeimmy Gonzalez-Masis, Jorge M. Cubero-Sesin, Alexander Campos-Quiros, Kaveh Edalati
Summary: In this study, biocompatible nanostructured high-entropy alloys were successfully synthesized using the high-pressure torsion method. The research compared the characteristics of different alloys and found that as the number of principal elements increased, hardness increased and grain size decreased, but these variations became less significant with further increase in configurational entropy.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Chemistry, Physical
Roman Sundeev, Anna Shalimova, Stanislav Rogachev, Olga Chernogorova, Alexander Glezer, Alexey Ovcharov, Igor Karateev, Natalia Tabachkova
Summary: A multi-metal composite was prepared by consolidating the Ti50Ni25Cu25 and Fe50Ni33B17 alloys using room-temperature high-pressure torsion (HPT). Structural research methods, such as X-ray diffractometry, high-resolution transmission electron microscopy, scanning electron microscopy, and measurement of indentation hardness and modulus, were employed in this study. The structural aspects of the bonding process were examined, and it was found that the method of coupled severe plastic deformation played a significant role in the consolidation of the dissimilar layers during HPT.
Article
Materials Science, Multidisciplinary
Jae-Kyung Han, Kunihisa Sugimoto, Megumi Kawasaki, Klaus-Dieter Liss
Summary: This study emphasizes the capability of high-energy synchrotron X-rays in investigating polymorphous phase transformations during nanostructuring and diffusion bonding of Al and Mg using high-pressure torsion. The measurements provide diffraction peak profiles at various local positions, allowing for the mapping of gradual yet significant structural changes in the Al-Mg nanocrystalline alloy, such as grain refinement and compositional broadening.
Article
Materials Science, Multidisciplinary
Xue Wang, Guangqing Chen, Mingming Wang, Keming Xue, Ping Li
Summary: By conducting high-pressure torsion (HPT) processing with a floating cavity, a W-Cu gradient material with noble bonding interface and significant grain refinement was successfully obtained. The microstructure evolution and atomic diffusion around the bonding interface were analyzed, showing that HPT processing can effectively refine the microstructure of tungsten and copper to a submicron level. The diffusion ability of tungsten and copper was enhanced by the high density of defects and ultrafine grains introduced by HPT processing.
INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
(2022)
Article
Nanoscience & Nanotechnology
Abhishek Rastogi, Suresh Neelakantan
Summary: In this study, stress-induced martensitic transformation (SIMT) has been effectively demonstrated to achieve a significant cold reduction of -43% and -45% in the metastable Ti-10V-2Fe-3Al and Ti-5Al-5V-5Mo-3Cr alloys, respectively. The presence of stress-induced alpha '' martensites provides preferential nucleation sites for new strain-free grains formation upon recrystallization annealing. Thermomechanical treatment results in a grain refinement of -93% and -80% for Ti-1023 and Ti-5553 alloys, respectively. The diffusivities of alloying elements, such as Fe, Mo, V, Cr, and Al, have been confirmed to alter the stability of the fl phase during recrystallization annealing, as evidenced by Electron Probe Micro Analyzer (EPMA). The effect of grain size on the SIMT ability based on microhardness variations has also been deduced.
SCRIPTA MATERIALIA
(2023)
Article
Materials Science, Multidisciplinary
Yoshifumi Ikoma
Summary: We investigated the effects of high-pressure torsion (HPT) processing on Si and related semiconducting materials, focusing on their phase transformations and electrical, thermal, and optical properties. The experiments revealed that HPT processing induced phase transformations in Si, resulting in the appearance of metastable phases such as Si-III, Si-XII, and Si-IV. The resistivity of Si decreased after HPT processing, and the thermal conductivity was significantly reduced. In addition, the HPT processing of Si0.5Ge0.5 crystal resulted in the formation of a metastable semimetallic phase, bc8-Si0.5Ge0.5. These findings suggest that HPT processing offers new opportunities for the development of novel devices utilizing nanograins and metastable phases.
MATERIALS TRANSACTIONS
(2023)
Article
Chemistry, Physical
Haruka Shimizu, Motohiro Yuasa, Hiroyuki Miyamoto, Kaveh Edalati
Summary: The influence of nanocrystalline structure produced by severe plastic deformation on the corrosion behavior of CoCrFeMnNi alloys was investigated. It was found that the impact of nanocrystalline structure on corrosion behavior was negligible.
Article
Nanoscience & Nanotechnology
Eunwook Jeong, Taehyeong Lee, Dooho Choi, Seung Min Yu, Sang-Geul Lee, Jong-Seong Bae, Seung Zeon Han, Gun-Hwan Lee, Yoshifumi Ikoma, Eun-Ae Choi, Jungheum Yun
Summary: This study demonstrates the effectiveness of atomic oxygen-mediated growth in synthesizing an ideal Au-layered structure with exceptional optoelectrical performance. The 4-nm-thick, quasi-single-crystalline Au layer exhibits record-low resistivity and minimal optical loss.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Chemistry, Physical
Gaspar Andrade, Guilherme Zepon, Kaveh Edalati, Abbas Mohammadi, Zhongliang Ma, Hai-Wen Li, Ricardo Floriano
Summary: The crystal structure and hydrogen storage properties of a new equiatomic TiZrNbCrFeNi high-entropy alloy (HEA) were investigated. The alloy exhibited an AB-type configuration, selected through thermodynamic calculations and showed the ability to absorb 1.5 wt% of hydrogen at room temperature without activation. Cyclical testing revealed changes in the fractions of two C14 Laves phases, with one phase having higher reactivity towards hydrogen. The alloy exhibited a single C14 Laves phase after dehydrogenation at 473 K, and microstructural analysis showed excellent homogeneity and element distribution.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Review
Chemistry, Physical
Saeid Akrami, Tatsumi Ishihara, Masayoshi Fuji, Kaveh Edalati
Summary: Excessive CO2 emission from fossil fuel usage has led to global warming and environmental crises. The photocatalytic conversion of CO2 to CO or useful components is a new strategy to address this issue. The main challenge is finding photocatalysts with high efficiency for CO2 photoreduction. Severe plastic deformation (SPD) has been used to develop active catalysts for CO2 conversion. These strategies can enhance photocatalytic efficiency by improving CO2 adsorption, increasing light absorbance, aligning the band structure, and providing active sites for photocatalytic reactions. This article reviews recent progress in using SPD to develop functional ceramics for photocatalytic CO2 conversion.
Review
Chemistry, Physical
Kaveh Edalati
Summary: Superfunctional materials refer to materials with specific properties that surpass those of engineering materials. Severe plastic deformation (SPD) has been widely studied as an effective means to enhance the functional and mechanical properties of metallic and non-metallic materials. Recently, the concept of ultra-SPD, which introduces shear strains exceeding 1000 to reduce the thickness of sheared phases to atomic distances, has been utilized to synthesize novel superfunctional materials. This article discusses the application of ultra-SPD in controlling atomic diffusion, phase transformation, and the synthesis of materials with superfunctional properties.
Article
Materials Science, Multidisciplinary
Abbas Mohammadi, Payam Edalati, Makoto Arita, Jae Wung Bae, Hyoung Seop Kim, Kaveh Edalati
Summary: In this study, three strategies are combined to achieve excellent strength-plasticity combinations in the presence of hydrogen embrittlement phenomena. First, an FCC high-entropy alloy with slow hydrogen lattice diffusion is selected. Second, aluminum is added to hinder surface-to-bulk hydrogen diffusion. Third, low-mobility lattice defects like nanotwins and Lomer-Cottrell locks are introduced by severe plastic deformation to suppress hydrogen-enhanced localized plasticity and stress concentration. The Al0.1CrFeCoNi alloy severely deformed by high-pressure torsion exhibits an ultrahigh yield strength of 1.96 GPa and a high elongation to failure of 10%.
Review
Materials Science, Multidisciplinary
Kaveh Edalati, Etsuo Akiba, Walter J. Botta, Yuri Estrin, Ricardo Floriano, Daniel Fruchart, Thierry Grosdidier, Zenji Horita, Jacques Huot, Hai-Wen Li, Huai-Jun Lin, Adam Revesz, Michael J. Zehetbauer
Summary: Magnesium and its alloys are extensively studied for solid-state hydrogen storage, but there are challenges in the kinetics and thermodynamics of hydrogenation and dehydrogenation. Severe plastic deformation methods have been utilized to improve the activation, air resistance, and kinetics of Mg-based hydrogen storage materials by introducing ultrafine/nanoscale grains and crystal lattice defects. These deformed materials, particularly with alloying additives or second-phase nanoparticles, exhibit fast hydrogen absorption/desorption kinetics and good cycling stability. The study also highlights the application of severe plastic deformation methods in hydrogen binding-energy engineering and the synthesis of new magnesium alloys for reversible low/room-temperature hydrogen storage.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2023)
Article
Nanoscience & Nanotechnology
Kazutoshi Takahashi, Yuki Umeda, Masaki Imamura, Marina Takaira, Yoshifumi Ikoma, Yasutomo Arai
Summary: The composition and structure of SiGe alloys play a key role in their electronic band structure, allowing for a wide range of applications. This study used high-resolution core-level and angle-resolved photoemission spectroscopy to investigate the surface of unstrained SiGe single crystals. The results showed a double domain reconstruction with an asymmetric dimer composed of Ge atoms and Si atoms located below the subsurface region. Additionally, three-dimensional ARPES measurements using synchrotron radiation revealed the compositional dependence of the valence bands.
Article
Crystallography
Shivam Dangwal, Kaveh Edalati, Ruslan Z. Z. Valiev, Terence G. G. Langdon
Summary: Strengthening and softening mechanisms in ultrafine-grained materials have been debated for many years. This study examines the Hall-Petch relationship in ultrafine-grained magnesium, aluminum, copper, and iron. The results show that while the materials follow the Hall-Petch relationship initially, an up-break occurs for grain sizes below 500-1000 nm. This is due to enhanced dislocation contribution. However, a down-break occurs for grain sizes smaller than 70-150 nm due to diminished dislocation contribution and increased thermally-activated phenomena. The study also finds that strategies other than grain refinement, such as microstructural stabilization by segregation or precipitation, are necessary to achieve extra strengthening.
Article
Materials Science, Multidisciplinary
Yoshifumi Ikoma
Summary: We investigated the effects of high-pressure torsion (HPT) processing on Si and related semiconducting materials, focusing on their phase transformations and electrical, thermal, and optical properties. The experiments revealed that HPT processing induced phase transformations in Si, resulting in the appearance of metastable phases such as Si-III, Si-XII, and Si-IV. The resistivity of Si decreased after HPT processing, and the thermal conductivity was significantly reduced. In addition, the HPT processing of Si0.5Ge0.5 crystal resulted in the formation of a metastable semimetallic phase, bc8-Si0.5Ge0.5. These findings suggest that HPT processing offers new opportunities for the development of novel devices utilizing nanograins and metastable phases.
MATERIALS TRANSACTIONS
(2023)
Article
Materials Science, Multidisciplinary
Qixin Guo, Junya Tetsuka, Zewei Chen, Makoto Arita, Katsuhiko Saito, Tooru Tanaka
Summary: MgGa2O4 films were grown on sapphire substrates at different substrate temperatures using pulsed laser deposition technique. The influence of substrate temperature on the properties of the films was systematically investigated. Deep ultraviolet (DUV) photodetectors based on these films exhibited excellent performance, indicating the potential for novel optoelectronic applications.
Review
Materials Science, Multidisciplinary
Parisa Edalati, Masayoshi Fuji, Kaveh Edalati
Summary: This article reviews the recent advances in the application of severe plastic deformation to developing superfunctional high-entropy materials, highlighting their superior properties for various mechanical and functional applications.
Article
Materials Science, Multidisciplinary
Alina Y. Morkina, Rita I. Babicheva, Elena A. Korznikova, Nariman A. Enikeev, Kaveh Edalati, Sergey V. Dmitriev
Summary: Molecular dynamics simulations were used to study the mechanical dissolution of Zr in Al. The orientation of the grain boundary was found to affect the mixing efficiency of alloy components, with a normal orientation promoting better dissolution of Zr.
Article
Chemistry, Physical
Bin Xu, Yuxuan Liao, Zhenglong Fang, Yifei Li, Rulei Guo, Ryohei Nagahiro, Yoshifumi Ikoma, Masamichi Kohno, Junichiro Shiomi
Summary: By applying a moderate high-pressure torsion (HPT) process on nanocrystalline silicon, the lattice thermal conductivity is further reduced by introducing finer nanostructures and internal strain. This study demonstrates a practical and feasible strain engineering strategy for achieving low thermal conductivity in various nanocrystalline materials.
JOURNAL OF MATERIALS CHEMISTRY A
(2023)
Review
Engineering, Chemical
Saeid Akrami, Parisa Edalati, Masayoshi Fuji, Kaveh Edalati
Summary: Nowadays, the environmental crisis caused by fossil fuels and CO2 emissions is a widespread concern. Photocatalysis is a promising clean technology for producing hydrogen fuel, converting harmful components, and degrading pollutants. However, the low efficiency of photocatalysis remains a significant drawback. Recent studies have shown that high-pressure torsion (HPT) can effectively improve the activity of conventional photocatalysts and synthesize highly efficient ones by increasing light absorbance, narrowing the bandgap, aligning the band structure, and decreasing electron-hole recombination through introducing lattice strain, vacancies, high-pressure phases, heterojunctions, and high-entropy ceramics. This review discusses the recent findings on improving photocatalyst efficiency through HPT processing and the parameters that contribute to these improvements.
KONA POWDER AND PARTICLE JOURNAL
(2023)
