Article
Materials Science, Multidisciplinary
N. Volz, F. Xue, C. H. Zenk, A. Bezold, S. Gabel, A. P. A. Subramanyam, R. Drautz, T. Hammerschmidt, S. K. Makineni, B. Gault, M. Goeken, S. Neumeier
Summary: The study found that at high temperatures, solutes such as Al, W, and Ta diffuse faster, leading to segregation and accelerated softening of the alloy, affecting creep properties. Partial dislocations facilitate shearing of the γ' precipitate phase through segregation during the early stages of creep. Thus, the poorer creep properties of the alloy at high temperatures are not only due to a smaller precipitate fraction, but also to faster diffusion-assisted shearing by partial dislocations.
Article
Chemistry, Physical
Qinghai Pan, Xinbao Zhao, Yuan Cheng, Quanzhao Yue, Yuefeng Gu, Hongbin Bei, Ze Zhang
Summary: In this study, the microstructure evolution of the fourth-generation nickel-based single crystal superalloys with different Co additions is investigated at three thermal exposure temperatures. The effects of Co content and aging temperatures on the coarsening rate of the gamma ' phase are analyzed based on LSW theory and TIDC theory. The results reveal that the diffusion coefficient of solute is accelerated, but the gamma/gamma ' interfacial energy decreases with the addition of Co, thus changing the coarsening rate. The alleviation of thermodynamic equilibrium solubility difference and element segregation at the gamma/gamma ' interface with Co increase suppresses the TCP phase after long-time thermal exposure, providing guidance for the economical design of nickel-based single crystal superalloys.
Article
Nanoscience & Nanotechnology
Prafull Pandey, Amit Sawant, Nithin Baler, Surendra K. Makineni, Kamanio Chattopadhyay
Summary: The addition of Ru enhances the microstructural stability of γ/γ' phase in Co-30Ni-10Al-5Mo-2Nb superalloy, reduces the interfacial energy of γ/γ', and increases the degree of anomalous strengthening.
SCRIPTA MATERIALIA
(2022)
Article
Nanoscience & Nanotechnology
Shasha Qu, Yingju Li, Min Tong, Cuiping Wang, Yuansheng Yang
Summary: Investigations on the coarsening behavior of gamma' precipitates and compression deformation mechanism of gamma'-strengthened CoNi-base superalloys showed that substituting Ta for W can increase the solvus temperature and decrease the mass density of the alloy. Different alloy compositions exhibit varying high-temperature strength and deformation behaviors, which are attributed to lattice mismatch effects.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Materials Science, Multidisciplinary
Yue Li, Zhijun Wang, Xianghan Gao, Yujian Wang, Junjie Li, Jincheng Wang
Summary: The kinetics of transient coarsening co-controlled by interface and matrix diffusion is studied in a new framework developed in the Lifshitz-Slyozov-Wagner space. The time for transient coarsening is found to change non-monotonically with the width and tail length of the initial distribution. A unique attractor state for the steady stage is identified, and the numerical origin of 'quasi-steady' distributions is revealed. The increase in volume fraction shortens the transient stage dominated by single mechanism but delays the transition to the diffusion-controlled stage.
Article
Nanoscience & Nanotechnology
Jiudong Sun, Jinlin Li, Hongyao Yu, Zhenhua Wang, Qing Wang, Chuang Dong
Summary: The present work focuses on the design of low-cost Ni-base superalloys with a high volume fraction of gamma' precipitates. The study finds that certain alloys exhibit high microstructural stability and slow coarsening rate, and a moderate lattice misfit contributes to the stability of the microstructure. Additionally, these alloys demonstrate excellent mechanical properties, with high yield strength and good microstructural stability.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Materials Science, Multidisciplinary
Chiraag Nataraj, Ruoshi Sun, Christopher Woodward, Axel van de Walle
Summary: This study investigates the effects of Al and Hf impurities on the (111) antiphase boundary energy of metastable FCC Co3W through ab initio calculations. The results show that sacrificial W compositions stabilize the L1(2) structure over a wider range of compositions than constant ratio compositions. Hf increases the APB energy far more than Al, particularly at higher concentrations, and at higher concentrations of Hf, Hf and W tend to segregate into alternating planes.
Article
Materials Science, Multidisciplinary
Jiachen Zhang, Taiwen Huang, Kaili Cao, Jia Chen, Huajing Zong, Dong Wang, Jian Zhang, Jun Zhang, Lin Liu
Summary: The microstructural evolution and γ' precipitate morphology of Re-containing Ni-based single crystal superalloys were significantly affected by the addition of Tantalum. Tantalum improved the microstructural stability and resistance to γ' coalescence in long-term aging. The calculated interfacial energy was used to elucidate the γ' kinetic pathways, with simulation results agreeing with experimental data, showcasing the reasonable nature of the model and parameters used.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2021)
Article
Chemistry, Physical
Amalia Navarro, Elisa Garcia-Tabares, Quentin M. Ramasse, Pablo Cano, Ignacio Rey-Stolle, Beatriz Galiana
Summary: Integration of GaP layers on silicon substrates using AsH3 pre-exposure followed by a PH3-based GaP epitaxial growth allows the development of very promising processes for the photovoltaic industry. However, many of the growth routines using this approach suffer from reproducibility issues, leading to poor quality layers. This lack of knowledge on the mechanisms behind the formation of common planar defects and their dynamics hinders the successful transfer of the method to new epitaxial systems.
APPLIED SURFACE SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
Vassili A. Vorontsov, Thomas P. McAuliffe, Mark C. Hardy, David Dye, Ioannis Bantounas
Summary: The tensile creep performance of a polycrystalline Co/Ni-base superalloy with a multimodal gamma' distribution was studied at 800 degrees C and 300 MPa. The rupture life of the alloy was comparable to that of RR1000 tested under similar conditions. Microstructural examination revealed the presence of continuous gamma' precipitates and M23C6 carbides along the grain boundaries, as well as the coarsening of the secondary gamma' precipitates. Long planar deformation bands, identified as microtwins, were observed along with the depletion of gamma' stabilising elements. The mechanism for precipitate dissolution was suggested to be the Kolbe reordering mechanism.
Article
Materials Science, Multidisciplinary
Fernando L. Reyes Tirado, David C. Dunand
Summary: The newly discovered CoeNbeV- and CoeTaeV-based superalloys exhibit excellent creep resistance due to a stable gamma+gamma' microstructure achieved with additional elements such as Ni, Cr, Ti, and Al. By increasing the concentration of all gamma'-formers, the alloys show a higher gamma'-volume fraction, with high stability and no formation of other phases even after aging at high temperatures.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2021)
Article
Materials Science, Multidisciplinary
Semanti Mukhopadhyay, Prafull Pandey, Nithin Baler, Krishanu Biswas, Surendra Kumar Makineni, Kamanio Chattopadhyay
Summary: The paper investigates the influence of Ti addition on Ta stabilized gamma/gamma' two-phase Co-based superalloys. It was found that an increase in Ti content reduces the gamma/gamma' lattice misfit and Mo partitioning to the gamma', while improving high-temperature strength. Additionally, aging of the alloys resulted in a morphological transition of the precipitates and a preference for Ti partitioning to the gamma'.
Article
Materials Science, Multidisciplinary
F. Xue, C. H. Zenk, L. P. Freund, S. Neumeier, M. Goeken
Summary: This study focuses on the compressive creep deformation behavior of a Co-base single-crystalline superalloy under high temperature/low stress conditions, with an emphasis on the mechanisms causing the local and global creep rate minima. It discusses how plate-like rafting and precipitate shearing contribute to decreasing creep rate until a global minimum is reached, followed by acceleration in the final creep stage. The formation of stacking faults, nano/microtwins, and ordered DO19-Co3W precipitates is also analyzed in detail, along with the differences in deformation mechanisms between Co- and Ni-base superalloys during double minimum creep.
PHILOSOPHICAL MAGAZINE
(2021)
Article
Chemistry, Physical
Jiachen Zhang, Taiwen Huang, Fan Lu, Kaili Cao, Dong Wang, Jian Zhang, Jun Zhang, Haijun Su, Lin Liu
Summary: The addition of 2 wt% Re significantly affected the stability of γ' precipitates in Ni-based single crystal superalloys during long-term aging, enhancing their stability and reducing lattice misfit. Re also decreased the effective diffusion coefficient of the alloy, effectively hindering the matrix-diffusion-controlled coarsening of γ' precipitates.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Materials Science, Multidisciplinary
Yao Zhang, Jinlin Li, Hongyao Yu, Jiudong Sun, Zhenhua Wang, Qing Wang
Summary: The present study investigated the effect of Ti, Nb, or Ta addition on the microstructural stability of coherent gamma/gamma ' phases in designed high-temperature alloys. The results showed that the addition of Ti, Nb, or Ta not only reduced the size of gamma ' nanoparticles, but also improved the microstructural stability during aging, leading to enhanced mechanical properties.
JOURNAL OF MATERIALS RESEARCH
(2023)
Review
Materials Science, Multidisciplinary
Jaclyn L. Cann, Anthony De Luca, David C. Dunand, David Dye, Daniel B. Miracle, Hyun Seok Oh, Elsa A. Olivetti, Tresa M. Pollock, Warren J. Poole, Rui Yang, C. Cem Tasan
Summary: Exciting metallurgical breakthroughs in recent decades have ushered in a new era in metals design, with the urgent need for new metallic materials to address current engineering challenges. While the environmental impact of the metallurgical industry is significant, the design of new metallic materials with improved properties can help tackle key environmental challenges.
PROGRESS IN MATERIALS SCIENCE
(2021)
Article
Materials Science, Multidisciplinary
C. R. Collins, F. F. Dear, D. Rugg, D. Dye
Summary: The study showed that nitrogen additions increase beta-transus temperature and strength, but decrease ductility, leading to reductions in both low cycle fatigue life and high cycle fatigue strength. Even small amounts of nitrogen can cause these effects, and neither microstructure nor fractographic examination is necessarily a reliable indicator of the presence of harmful nitrogen contamination.
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
(2021)
Article
Materials Science, Multidisciplinary
T. P. McAuliffe, I. Bantounas, L. R. Reynolds, A. Foden, M. C. Hardy, T. B. Britton, D. Dye
Summary: A correlative approach was used to assess the structure and chemistry of carbide and boride precipitates in novel Co/Ni-based superalloys. The principal carbide was found to be Mo and W rich with the M6C structure, while a Mo and W segregated M2B boride was observed at higher boron levels. The study highlights the importance of combining chemical and structural fingerprinting for accurate phase characterization.
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
(2021)
Article
Materials Science, Multidisciplinary
Felicity F. Dear, Paraskevas Kontis, Baptiste Gault, Jan Ilavsky, David Rugg, David Dye
Summary: The nucleation and growth of Ti3Al alpha(2) ordered domains in alpha-Ti-Al-X alloys were characterized using various techniques, showing that the addition of solutes such as Mo can increase nucleation density and decrease precipitate size and coarsening rate. The study also found that solutionizing temperature affects nucleation number density, supporting the hypothesis that vacancy concentration affects alpha(2) nucleation. Observation that all solutes increase nucleation number density is consistent with a vacancy-controlled nucleation mechanism.
Article
Materials Science, Multidisciplinary
Yitong Shi, Sudha Joseph, Edward A. Saunders, Rebecca S. Sandala, Adrian Walker, Trevor C. Lindley, David Dye
Summary: The mechanism of AgCl-induced stress corrosion cracking of Ti-6246 involves the formation and migration of metallic Ag along the crack, as well as the presence of SnO2 and Al2O3 corrosion products mixed into TiO2. The fracture surface exhibits a transgranular nature with a brittle appearance in the primary alpha phase, where long, straight and non-interacting dislocations are observed. This is consistent with a dislocation emission view of the cracking mechanism.
Article
Nanoscience & Nanotechnology
Guohua Zhao, Xin Xu, David Dye, Pedro E. J. Rivera-Diaz-del-Castillo, Nik Petrinic
Summary: This study reported a method to deploy transformation-mediated strengthening in titanium alloys by supervised activation of TRIP and TWIP through mechanism-driven modelling, improving the mechanical properties of materials. By developing new alloys, notable resistance to strain localization was achieved, along with significant strain-hardening effects.
SCRIPTA MATERIALIA
(2022)
Article
Materials Science, Multidisciplinary
Vassili A. Vorontsov, Thomas P. McAuliffe, Mark C. Hardy, David Dye, Ioannis Bantounas
Summary: The tensile creep performance of a polycrystalline Co/Ni-base superalloy with a multimodal gamma' distribution was studied at 800 degrees C and 300 MPa. The rupture life of the alloy was comparable to that of RR1000 tested under similar conditions. Microstructural examination revealed the presence of continuous gamma' precipitates and M23C6 carbides along the grain boundaries, as well as the coarsening of the secondary gamma' precipitates. Long planar deformation bands, identified as microtwins, were observed along with the depletion of gamma' stabilising elements. The mechanism for precipitate dissolution was suggested to be the Kolbe reordering mechanism.
Article
Nanoscience & Nanotechnology
T. W. J. Kwok, K. M. Rahman, V. A. Vorontsov, D. Dye
Summary: This study investigated the effect of hot rolling temperature on the mechanical properties of a Fe-28Mn-8Al-1.0C steel. It was found that lower temperature rolling significantly increased the yield strength without compromising the elongation to failure. The improvement in strength was attributed to the increase in residual dislocation density, which was retained even after the ageing heat treatment. The homogeneous precipitation of kappa-carbides indicated that the high residual dislocation density did not adversely affect precipitation kinetics.
SCRIPTA MATERIALIA
(2022)
Article
Materials Science, Multidisciplinary
X. Xu, T. W. J. Kwok, P. Gong, D. Dye
Summary: The novel concept of varying the strain hardening rate of medium Mn steel by adjusting the intercritical annealing duration was explored, revealing a relationship between austenite stability and strain hardening rate. The continuous Mn enrichment with increasing intercritical annealing duration was found to be the cause of the change in austenite stability. Twinned martensite was identified as the likely product of martensitic transformation during deformation.
Article
Materials Science, Multidisciplinary
Yuhe Huang, Junheng Gao, Vassili Vorontsov, Dikai Guan, Russell Goodall, David Dye, Shuize Wang, Qiang Zhu, W. Mark Rainforth, Iain Todd
Summary: This study reports a novel dynamic strengthening mechanism, martensitic twinning transformation mechanism, in a metastable refractory element-based BCC-HEA that can greatly enhance the work hardening capability and achieve both high ductility and strength. By analyzing the microstructure, it is found that the martensitic twinning transformation mechanism combines the best characteristics of transformation-induced plasticity and twinning-induced plasticity, effectively alleviating the strength-ductility trade-off.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2022)
Article
Nanoscience & Nanotechnology
T. W. J. Kwok, P. Gong, R. Rose, D. Dye
Summary: Two different microstructures of medium Mn steel were obtained through different approaches in hot rolling mill, showing a simultaneous twinning induced plasticity and transformation induced plasticity (TWIP + TRIP) mechanism. However, twinning contributed relatively little to the strength of the alloy, mainly due to the small initial slip lengths that reduced the opportunity for grain work hardening.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Multidisciplinary Sciences
Felicity F. Worsnop, Rachel E. Lim, Joel Bernier, Darren C. Pagan, Yilun Xu, Thomas P. McAuliffe, David Rugg, David Dye
Summary: In this study, stress bursts at the scale of individual grains were observed using high energy X-ray diffraction microscopy, revealing the effect of precipitation and trace impurities on slip bursts. By reducing the magnitude of slip bursts and increasing the frequency of smaller events, trace impurities contribute to the reduction of dwell fatigue.
NATURE COMMUNICATIONS
(2022)
Article
Nanoscience & Nanotechnology
Samuel R. Rogers, Jaimie Daure, Philip Shipway, David Stewart, David Dye
Summary: Research and development of wear-resistant steels is being carried out to reduce cobalt within the primary circuit of PWR's. The focus is on understanding galling mechanisms, particularly prevalent in PWR valves. Findings show that large shear stresses and adhesive transfer occur during galling due to the difference in manganese content between 304L and 316L stainless steels, even at relatively low compressive stresses of 50MPa.
SCRIPTA MATERIALIA
(2022)
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
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.