Article
Engineering, Manufacturing
Shaaz Ghouse, Reece N. Oosterbeek, Aisha Tayub Mehmood, Filippo Vecchiato, David Dye, Jonathan R. T. Jeffers
Summary: Utilizing vacuum heat treatment can adjust the micro- and macro-structure of porous AM Ti-6Al-4V, thereby improving crucial fatigue resistance. By optimizing heat treatment procedures, comparable alloy microstructures can be obtained, increasing fatigue strength.
ADDITIVE MANUFACTURING
(2021)
Article
Nanoscience & Nanotechnology
Mohammad Jamalkhani, Bradley Nathan, Mike Heim, Dave Nelson, Amir Mostafaei
Summary: The study investigated the influence of surface roughness on the high-cycle fatigue properties of vacuum sintered binder jetted gas atomized fine 316L stainless steel powder. The results showed that mechanical grinding can significantly improve the surface roughness and enhance the fatigue life. The study also revealed the relationship between residual stress and surface hardness on the mechanically ground samples.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Engineering, Mechanical
Arnaud Junet, Alexandre Messager, Arnaud Weck, Yves Nadot, Xavier Boulnat, Jean-Yves Buffiere
Summary: Fatigue specimens of a Ti-6Al-4V alloy containing internal artificial defects were studied. The growth of internal fatigue cracks was monitored in situ by synchrotron X-ray tomography during fatigue tests. Ex situ fatigue tests were also performed on samples with heat treatment or defects exposed to air. The results indicate that internal fatigue cracks grow from the notch in a vacuum environment and exhibit specific fracture surface regions.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Article
Engineering, Mechanical
J. Geathers, C. J. Torbet, J. W. Jones, S. Daly
Summary: Water vapor has a significant impact on the small fatigue crack growth rates in Ti-6242S alloy, with a linear dependence observed between crack growth rate and water vapor pressure. This work highlights the importance of humidity in determining fatigue life even at high cyclic frequencies.
INTERNATIONAL JOURNAL OF FATIGUE
(2022)
Article
Materials Science, Multidisciplinary
Dmitrii Zaguliaev, Yurii Ivanov, Suresh Gudala, Oleg Tolkachev, Krestina Aksenova, Sergey Konovalov, Vitaly Shlyarov
Summary: This study found that under the same applied stress amplitude, the coating thickness of 5μm had the longest fatigue life, which may be attributed to its good resistance capability. The fatigue life of a coating thickness of 1μm was lower, possibly due to the fracture of the coating layer under the strong influence of substrate deformation.
Article
Mechanics
B. Gholami Bazehhour, S. Srinivasan, C. Kale, P. Peralta, K. Solanki
Summary: In this study, fatigue crack growth experiments were conducted in commercial purity titanium with different initial oxygen contents and load ratios (R). A fatigue indicator parameter (FIP) along with high-resolution crystal plasticity simulations were used to model fatigue crack initiation and growth. The calibrated parameters were used to predict crack nucleation and microstructurally short crack (MSC) growth behavior, showing the potential of this approach.
ENGINEERING FRACTURE MECHANICS
(2023)
Article
Chemistry, Physical
Johannes L. Otto, Ivan Fedotov, Milena Penyaz, Thorge Schaum, Anke Kalenborn, Boris Kalin, Oleg Sevryukov, Frank Walther
Summary: Alumina-based ceramic hip endoprosthesis heads have excellent tribological properties, but stress peaks at the point of contact with the stem pose a risk. A fixed titanium insert in the ceramic ball head can reduce stress peaks, and brazing is a viable method for forming a permanent titanium-ceramic joint.
Article
Engineering, Mechanical
Fumiyoshi Yoshinaka, Takashi Nakamura, Hiroyuki Oguma, Nao Fujimura, Akihisa Takeuchi, Masayuki Uesugi, Kentaro Uesugi
Summary: The initiation of internal fatigue cracks in very high cycle fatigue of Ti-6Al-4V alloy was investigated using synchrotron radiation X-ray computed tomography (SR-CT). Micro-CT detected 28 cracks that were distributed across the examined volume of CYRILLIC CAPITAL LETTER EF1.8 x L 2.5 mm. No apparent correlation was observed between the spatial distribution, initial lengths, and initiation lives of cracks. The crack growth rate of the facet-sized crack varied widely; some cracks propagated rapidly, whereas no crack growth was observed for other cracks over a specific period of time after detection. Using nano-CT, the several grain-sized internal cracks and their microstructures were clearly and nondestructively visualized. In the field of view, many primary alpha phases were detected; however, no other cracks were observed. The multiple facet initiation site, which is commonly observed for titanium alloys, might not be due to the concurrently initiated facets but may be caused by the small crack growth accompanied by facet formation.
FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES
(2023)
Article
Materials Science, Multidisciplinary
C. Lavogiez, C. Dureau, Y. Nadot, P. Villechaise, S. Hemery
Summary: The fatigue behavior of Ti-6Al-4V with a bi-modal microstructure was investigated using different waveforms, load ratios, and frequencies. It was found that cracks were initiated along (0001) twist grain boundaries, which is consistent with prior studies. The results also showed that the critical microstructural configurations were not sensitive to environmental factors, free surfaces, loading conditions, and microstructure and composition.
Article
Materials Science, Multidisciplinary
Conghui Liu, Rhys Thomas, Tianzhu Sun, Jack Donoghue, Xun Zhang, Tim L. Burnett, Joao Quinto da Fonseca, Michael Preuss
Summary: In this study, the relationship between plastic slip activity and fatigue crack initiation was investigated in a near-alpha titanium alloy. The findings showed that plasticity at low stress levels was dominated by basal slip and two types of cracking were observed parallel to basal slip traces. Detailed analysis revealed the mechanisms behind the crack initiation, such as out-of-plane Burgers vector activity and crystallographic facet formation. A new parameter was developed based on the geometric factors to predict transgranular surface crack initiation sites.
Article
Crystallography
Baohua Nie, Shuai Liu, Yue Wu, Yu Song, Haiying Qi, Binqing Shi, Zihua Zhao, Dongchu Chen
Summary: The effect of low cycle fatigue (LCF) predamage with no precracks on very high cycle fatigue (VHCF) properties and crack initiation characteristics for TC21 titanium alloy was investigated. It was found that LCF predamage with less than 5% of fatigue life had minimal impact on fatigue limit but reduced fatigue life. Fatigue cracks initiated on the surface of the specimen at high stress amplitudes, while fatigue cracks initiated below the surface at low stress amplitudes. A combined fatigue damage model was established based on Lemaitre damage theory, and it showed consistency with experimental data. The fatigue crack initiation of specimens with LCF predamage less than 5% accounted for a significant portion of fatigue life.
Article
Engineering, Mechanical
Emre Akgun, Xiang Zhang, Romali Biswal, Yanhui Zhang, Matthew Dore
Summary: The failure of additive manufactured titanium alloy Ti-6Al-4V is primarily attributed to process-induced defects rather than pore size. Embedded pores below approximately 85 µm threshold size can achieve wrought level fatigue performance.
INTERNATIONAL JOURNAL OF FATIGUE
(2021)
Article
Chemistry, Physical
Yang Zhou, Fang Yang, Cunguang Chen, Yanru Shao, Boxin Lu, Yanli Sui, Zhimeng Guo
Summary: High-plasticity in-situ TiB/Ti matrix composites with uniform microstructure and grain refinement were fabricated by vacuum sintering and hot rolling. The Ti-2.0 wt% ZrB2 composite exhibited outstanding mechanical properties, attributed to grain refinement and dominant role of dislocation substructure hardening.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Engineering, Mechanical
S. Hemery, J. C. Stinville
Summary: This study monitored the microstructurally small crack growth in Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo with equiaxed and bimodal microstructures. The influence of microstructure on the lifetime variability observed in Ti alloys was evaluated, and primary alpha grains, basal plane cracking, and misalignment across boundaries were identified as key features for high crack growth rates. Dwell periods were found to induce significant small crack acceleration.
INTERNATIONAL JOURNAL OF FATIGUE
(2022)
Article
Engineering, Mechanical
Zhiyuan Gao, Xin Chen, Siyao Zhu, Yuhuai He, Wei Xu
Summary: The notch fatigue behavior of a titanium alloy TC17 in the VHCF regime is investigated. A complete S-N relation of notched specimens with high resonance frequencies is obtained, covering the lifetime up to 10^9 cycles, and the fracture surfaces are observed. The TC17 exhibits relatively high fatigue notch sensitivity, and several fatigue crack initiation mechanisms are revealed. Furthermore, a notch fatigue prediction model based on a modified theory of critical distance is proposed, which has good prediction accuracy.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Letter
Critical Care Medicine
Jan C. Kamp, Christopher Werlein, Edith K. J. Plucinski, Lavinia Neubert, Tobias Welte, Peter D. Lee, Paul Tafforeau, Claire Walsh, Mark P. Kuehnel, Detlef Schuppan, Marius M. Hoeper, Danny D. Jonigk, Maximilian Ackermann
AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE
(2023)
Letter
Respiratory System
Maximilian Ackermann, Paul Tafforeau, Joseph Brunet, Jan C. Kamp, Christopher Werlein, Mark P. Kuehnel, Joseph Jacob, Claire L. Walsh, Peter D. Lee, Tobias Welte, Danny D. Jonigk
EUROPEAN RESPIRATORY JOURNAL
(2023)
Article
Engineering, Biomedical
C. M. Disney, N. T. Vo, A. J. Bodey, B. K. Bay, P. D. Lee
Summary: In-line phase contrast synchrotron tomography combined with in situ mechanical loading allows for the characterization of soft tissue micromechanics using DVC. Optimization of scan time is important for reducing radiation dose and sample movement. The influence of phase contrast imaging on DVC accuracy has been investigated in this study.
JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS
(2023)
Article
Geosciences, Multidisciplinary
Rafael Torres-Orozco, Shane J. Cronin, Natalia Pardo, Szabolcs Kosik, Ingrid Ukstins, Mirja Heinrich, Peter D. Lee
Summary: Estimating the kinetics of andesite magma vesiculation and crystallization is crucial for understanding volcanic eruption dynamics. In this study, we used synchrotron microtomography and other techniques to quantify the size and shape distributions of vesicles and crystals in pyroclasts from the Mount Taranaki eruption. Our findings reveal the complex fragmentation mechanisms of andesite magmas during different phases of the eruption.
JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH
(2023)
Article
Materials Science, Multidisciplinary
Sophie A. M. McNair, Jiraphant Srisuriyachot, Samuel Omole, Thomas Connolley, Andrew Rhead, Alexander J. G. Lunt
Summary: Small-diameter, thin-walled pipes are widely used in industries such as high-energy physics, heat transfer, nuclear, medical, and communications. The performance of thin-walled pipe welds less than 0.5 mm in width is difficult to determine due to the lack of existing standards. Porosity is a determining factor in the performance of the connection. This study found that reducing residual stresses is more important than reducing porosity for improving weld strength.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2023)
Article
Chemistry, Physical
Chu Lun Alex Leung, Matthew D. Wilson, Thomas Connolley, Stephen P. Collins, Oxana Magdysyuk, Matthieu N. Boone, Kosuke Suzuki, Matthew C. Veale, Enzo Liotti, Frederic Van Assche, Andrew Lui, Chun Huang
Summary: Increasing electrode thickness is considered as a potential method to improve energy density in Li ion batteries. However, the diffusion of Li+ ions during (dis)charge, especially at higher rates, limits the realizable capacity and rate capability. Visualizing and quantifying Li+ chemical stoichiometry distribution inside the electrode within commercially standard battery geometry is still challenging. In this study, the distribution of Li+ chemical stoichiometry in the electrode microstructure of a working coin cell battery is mapped using innovative in situ correlative full-field X-ray Compton scattering imaging (XCS-I) and X-ray computed tomography (XCT).
MATERIALS TODAY ENERGY
(2023)
Article
Materials Science, Multidisciplinary
Xingxing Li, Xinghai Yang, Chengpeng Xue, Shuo Wang, Yuxuan Zhang, Bing Wang, Junsheng Wang, Peter D. Lee
Summary: In this study, a three-dimensional multicomponent cellular automaton (CA) model coupled with CALPHAD calculations was used to simulate the nucleation and growth of hydrogen porosity and its interaction with surrounding dendritic structures during the solidification of Al-Cu-Li alloys. The effects of hydrogen concentration, cooling rate, and Li content on solidification conditions were quantified, resulting in effective reduction of porosity size. X-ray computed tomography (XCT) was utilized to validate the model and revealed that porosity exhibited elongated and tortuous shape at slow cooling rates, filling up the empty spaces of secondary arms, while it tended to be dispersed spherical shape at high cooling rates when its surrounding grains became equiaxed structures.
COMPUTATIONAL MATERIALS SCIENCE
(2023)
Article
Engineering, Manufacturing
Gowtham Soundarapandiyan, Chu Lun Alex Leung, Carol Johnston, Bo Chen, Raja H. U. Khan, Phil McNutt, Alisha Bhatt, Robert C. Atwood, Peter D. Lee, Michael E. Fitzpatrick
Summary: This study uses in situ high speed synchrotron X-ray imaging to investigate the effects of low and high oxygen content Ti6Al4V powders on laser-matter interactions, process, and defect dynamics during multilayer thin-wall laser powder bed fusion (L-PBF). The results show that high oxygen content Ti6Al4V powder can reduce melt ejections, surface roughness, and defect population in the built parts. Increasing oxygen content in the part leads to an increase in microhardness due to solid solution strengthening, with no significant change in the microstructure.
INTERNATIONAL JOURNAL OF MACHINE TOOLS & MANUFACTURE
(2023)
Review
Materials Science, Multidisciplinary
T. W. J. Kwok, D. Dye
Summary: Medium Mn steels are emerging third-generation advanced high-strength steels with high strengths, large ductilities, and lower costs compared to their predecessor high Mn TWIP steels. They exhibit TWIP and/or TRIP effects, which contribute to a high strain hardening rate. The current review focuses on the alloy design, processing, microstructure, and property relationships of medium Mn steels, complementing the review by Sun et al. [Physical metallurgy of medium-Mn advanced high-strength steels, Int Mater Rev. 2023.], which primarily discusses phase interfaces and thermodynamics.
INTERNATIONAL MATERIALS REVIEWS
(2023)
Article
Biochemical Research Methods
J. Brunet, C. L. Walsh, W. L. Wagner, A. Bellier, C. Werlein, S. Marussi, D. D. Jonigk, S. E. Verleden, M. Ackermann, Peter D. Lee, Paul Tafforeau
Summary: The authors present a protocol for preparing and mounting whole human organs for X-ray hierarchical phase-contrast tomography, resulting in high-resolution images. Imaging across different scales is crucial for understanding organ morphology and pathophysiological changes. The protocol enables scanning of large soft-tissue samples, including intact human organs, with enhanced contrast and reduced sample movement and bubble formation.
Article
Materials Science, Multidisciplinary
Xianqiang Fan, Natalia Shevchenko, Catherine Tonry, Samuel J. Clark, Robert C. Atwood, Sven Eckert, Koulis Pericleous, Peter D. Lee, Andrew Kao
Summary: Solute channel formation can occur in various processes and is influenced by the interaction between an external magnetic field and thermoelectric currents at solid/liquid interfaces. In this study, we used in situ synchrotron X-ray imaging and numerical simulations to investigate the characteristics of flow and solute transport under thermoelectric magnetohydrodynamic (TEMHD) effects. Our observations suggest that macroscopic and microscopic TEMHD flows are the primary mechanisms controlling plume migration and channel bias. We also discovered that grain orientation can modify solute flow through anisotropic permeability. These findings led to the proposed strategy of using a time-modulated magnetic field for solute channel-free solidification.
Article
Materials Science, Multidisciplinary
David T. Rees, Chu Lun Alex Leung, Joe Elambasseril, Sebastian Marussi, Saurabh Shah, Shashidhara Marathe, Milan Brandt, Mark Easton, Peter D. Lee
Summary: In this study, two approaches, including TiB2 additions and optimization of LPBF process parameters, were used to suppress the formation of hot cracks in laser powder bed fusion (LPBF) additive manufacturing of 2XXX series Al alloys. High-speed synchrotron X-ray radiography and high-resolution synchrotron X-ray computed tomography (sCT) were used to monitor the LPBF process and measure the volume fraction of defects in the as-built samples. The results showed that adding TiB2 in Al-2139 reduced the volume of cracks by up to 79% and decreased the average length, breadth, and surface area of cracks.
MATERIALS & DESIGN
(2023)
Article
Materials Science, Multidisciplinary
Caterina Iantaffi, Eral Bele, David Mcarthur, Peter D. Lee, Chu Lun Alex Leung
Summary: This study investigates the compressive performance of auxetic cubic chiral structures, finding that energy absorption and auxeticity are dependent on the relative density of the constitutive struts. The research also reveals that in the plastic regime, the auxeticity decreases with relative density.
MATERIALS & DESIGN
(2023)
Article
Nanoscience & Nanotechnology
Y. Chen, Y. T. Tang, D. M. Collins, S. J. Clark, W. Ludwig, R. Rodriguez-Lamas, C. Detlefs, R. C. Reed, P. D. Lee, P. J. Withers, C. Yildirim
Summary: The industrialization of Laser Additive Manufacturing (LAM) faces challenges such as undesirable microstructures and high residual stresses. Non-destructive assessment of mechanical performance is crucial, and Dark Field X-ray Microscopy (DFXM) is used to map the 3D subsurface intragranular orientation and strain variations of a surface-breaking grain in a nickel superalloy. DFXM results show a highly heterogeneous microstructure with alternating strain states and small orientation differences. Comparison with Electron Backscatter Diffraction measurements is also discussed.
SCRIPTA MATERIALIA
(2023)
Article
Materials Science, Multidisciplinary
Ching Kiat Yong, Elspeth M. Keating, Darren J. Hughes, Thomas Connolley, Geoff West, Chow Cher Wong, Gregory J. Gibbons
Summary: For the first time, the through-thickness residual strain profile of an additively-manufactured IN718 sample due to laser shock peening (LSP) is demonstrated. This provides valuable insights into the potential of using LSP to extend the fatigue life of additively-manufactured samples. The peening process led to significant beneficial compressive in-plane residual strains, extending to a depth of 1.0mm.
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.
