Article
Materials Science, Multidisciplinary
Yu Guo, Meng Wang, Kai Wang, S. H. Song
Summary: The study aims to establish the relationship between phosphorus GBS and embrittlement in RPV steel, demonstrating a linear correlation between DBTT and phosphorous GBS concentration, and identifying the rate of material embrittlement associated with grain-boundary embrittlement and total GB area per unit volume. It also reveals a critical phosphorous GBS concentration affecting the embrittlement of specimens with different grain sizes.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2022)
Article
Materials Science, Multidisciplinary
Kai Wang, Yu Guo, Shenhua Song
Summary: The study focuses on investigating the non-hardening embrittlement caused by grain boundary segregation of P in a P-doped SA508-4 N steel through impact testing in conjunction with Auger electron spectroscopy and microstructural characterization. Results show a linear dependence of DBTT on the boundary concentration of P when steel hardness is fixed. A time-temperature embrittlement diagram is developed based on the DBTT-segregation relation, which can be used to predict embrittlement tendency in the steel.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2021)
Article
Materials Science, Multidisciplinary
Kuniki Hata, Hisashi Takamizawa, Tomohiro Hojo, Kenichi Ebihara, Yutaka Nishiyama, Yasuyoshi Nagai
Summary: Neutron irradiation increased grain-boundary P segregation in RPV steels, but the increase was minimal for steels with a bulk P content of 0.015wt.% at 1 x 10(20) n/cm(2) (E > 1 MeV). Neutron flux had no effect on grain-boundary P segregation in A533B steels. The relationship between yield strength and DBTT shift in RPV steels was linear with a slope of 0.63.
JOURNAL OF NUCLEAR MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
Ahjeong Lyu, Junghoon Lee, Jae-Hoon Nam, Minjeong Kim, Young-Kook Lee
Summary: In this study, the H absorption and H embrittlement (HE) resistance of medium (3-7 wt%) Mn martensitic steels were investigated. The 7 wt% Mn specimen had the highest diffusible H content due to the highest reversible H trap density when the specimens were electrochemically H-charged. When the diffusible H content was the same, the HE resistance deteriorated due to Mn addition, possibly caused by grain boundary decohesion and H segregation into the grain boundaries. However, this condition was improved by B addition due to enhanced grain boundary cohesion and suppression of H segregation into the grain boundaries.
Article
Chemistry, Multidisciplinary
Ali Ahmadian, Daniel Scheiber, Xuyang Zhou, Baptiste Gault, Lorenz Romaner, Reza D. Kamachali, Werner Ecker, Gerhard Dehm, Christian H. Liebscher
Summary: The embrittlement of metallic alloys by liquid metals is a serious problem that affects their structural integrity. This study reveals how boron segregation can mitigate the detrimental effects of zinc, a prime embrittler, in a specific type of grain boundary in alpha-Fe (4 at.% Al). Zinc induces nanoscale segregation patterns that result in complex grain boundary states. Ab initio simulations show that boron inhibits zinc segregation and compensates for the loss of grain boundary cohesion caused by zinc. This research sheds new light on how interstitial solutes can modify grain boundaries and suggests their potential use as dopants to prevent material failure.
ADVANCED MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
M. C. Niu, C. J. Chen, W. Li, K. Yang, J. H. Luan, W. Wang, Z. B. Jiao
Summary: Understanding the solute interaction effects on grain boundary segregation, precipitation, and fracture of Fe-Ni-Ti-(Mo) maraging steels is crucial for the development of improved steel performance. The addition of Mo effectively suppresses intergranular embrittlement by reducing the segregation of Ni and Ti, inhibiting the formation of coarse Ni3Ti precipitates and precipitate-free zones at grain boundaries, and enhancing grain boundary cohesion.
Article
Materials Science, Multidisciplinary
Qi Chen, Rong Hu, Shenbao Jin, Fei Xue, Gang Sha
Summary: This study investigated the irradiation-induced segregation of solutes at typical grain boundaries in Fe-Mn-Si steel, revealing that Mn and C segregate at grain boundaries and the extent of segregation depends on the characteristics of the boundaries, with the strongest segregation observed at random high-angle boundaries.
Article
Materials Science, Multidisciplinary
Xin Dong, Xiaobing Li, Weiwei Xing, Leilei Ding, Yingche Ma, Kui Liu, Nannan Zhang
Summary: The study shows that the addition of magnesium can improve the impact toughness of 2.25Cr1Mo steel to some extent and segregate to the grain boundaries during aging, reducing the grain boundary segregation of phosphorus. Additionally, magnesium also regulates the grain characteristics and the effects of carbides at grain boundaries.
Article
Nanoscience & Nanotechnology
Kazuho Okada, Akinobu Shibata, Taisuke Sasaki, Hisashi Matsumiya, Kazuhiro Hono, Nobuhiro Tsuji
Summary: This study aimed to improve the resistance against hydrogen embrittlement by increasing the concentration of carbon segregated at prior austenite grain boundary (PAGB), XPAGB, in low-carbon martensitic steels. The specimens with and without carbon segregation treatment (Non-seg and Seg specimens, respectively) had similar microstructures, except for higher XPAGB in the Seg specimen. The Seg specimen exhibited higher maximum stress and smaller fraction of intergranular fracture surface under hydrogen-charged conditions, indicating that segregated carbon suppressed hydrogen accumulation and increased cohesive energy of PAGB.
SCRIPTA MATERIALIA
(2023)
Article
Materials Science, Multidisciplinary
Jingliang Wang, Masato Enomoto, Chengjia Shang
Summary: First-principles calculations were conducted to investigate the Sigma 5(310) grain boundary in Fe with B, C, and P, revealing the embrittlement caused by P and the de-embrittling effect of B and C. The energetic preference of interstitial B and C over interstitial P was found, with only substitutional P exacerbating grain boundary cohesion. The study demonstrated that the influence of these elements on the grain boundary cohesion is a complex interplay between mechanical and chemical contributions.
Article
Chemistry, Multidisciplinary
Yong Zhou, Fuan Yan
Summary: The purpose of this study was to investigate the initiation mechanism of grain boundary dissolution (GBD) for carbon steels in acidic electrolytes containing NO2-. Both electrochemical and surface methods were used to explore the electrochemical behavior, surface microstructure, and composition of Q235 carbon steel in a HNO3-NaNO2 solution with pH 4. It was found that GBD occurred at the high Si-Mn grain boundaries when Q235 carbon steel was polarized to the active-passive transition potential. The grain boundary segregations of Si and Mn played a critical role in the initiation of GBD.
JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
(2023)
Article
Materials Science, Multidisciplinary
X. H. Chen, X. Q. Zhuang, J. W. Mo, J. Y. He, T. Yang, X. Y. Zhou, W. H. Liu
Summary: The study demonstrates that boron doping can effectively reduce the ductility loss and enhance the resistance to hydrogen embrittlement in CrCoNi medium-entropy alloy, by improving grain-boundary cohesion and reducing hydrogen diffusivity.
MATERIALS RESEARCH LETTERS
(2022)
Article
Nanoscience & Nanotechnology
A. Rapetti, F. Christien, F. Tancret, P. Todeschini, S. Hendili, J. Stodolna
Summary: The sensitivity to ductility dip cracking was significantly different in two high chromium nickel alloys with different sulphur contents. Postmortem analyses revealed no segregation of sulphur at grain boundaries, but grain boundary fracture surfaces are covered with sulphur. It is suggested that sulphur plays a role as a surfactant in dynamic grain boundary embrittlement, facilitating crack opening.
SCRIPTA MATERIALIA
(2021)
Article
Materials Science, Multidisciplinary
Daniel Scheiber, Lorenz Romaner
Summary: There is substantial disagreement between experimentally measured and first principles calculated values for segregation energies. By computing segregation of five different elements to the same grain boundaries as studied in previous experiments, it was found that the multi-site nature of segregation leads to artificial temperature dependence in the single site effective segregation energy. Taking this into account significantly improves the agreement between experiment and theory, and clarifies the nature of experimentally determined segregation enthalpies and entropies.
Article
Metallurgy & Metallurgical Engineering
Xiao-bing Li, Xin Dong, Peng-xiang Zhao, Wei-wei Xing, Lei-lei Ding, Nan-nan Zhang, Ying-che Ma, Kui Liu
Summary: By adding trace Mg to 2.25Cr-1Mo steel, the temper embrittlement susceptibility induced by P can be reduced, mainly attributed to the segregation of Mg at grain boundary. This segregation decreases the segregation amounts of P and S, especially for P, and enhances grain boundary cohesion, thus alleviating the adverse effect on temper embrittlement caused by P and S.
JOURNAL OF IRON AND STEEL RESEARCH INTERNATIONAL
(2021)
Article
Materials Science, Multidisciplinary
Tahereh Zargar, Fazlollah Sadeghi, Jong Wan Kim, Jae Sang Lee, Yoon-Uk Heo, Chang Hee Yim
Summary: The Thermo-Calc software was used to predict the M-shaped delta-ferrite content in continuously cast 304 austenitic stainless steel slab, with the moving-boundary model showing accurate results when compared to observations. Analysis of different cooling rates revealed a more significant reduction in delta-ferrite under fast solidification rates.
METALS AND MATERIALS INTERNATIONAL
(2022)
Article
Materials Science, Ceramics
Minoru Maeda, Yoon-Uk Heo, Jun Hyuk Choi, Dipak Patel, Su-Hun Kim, Seungyong Hahn, Jung Ho Kim, Seyong Choi
Summary: Powder processing by ball milling is an effective method for structural modification of superconducting materials. Low-rotation shaker was used to achieve structural modification by controlling processing parameters and enhancing energy transfer. The morphological changes of the processed powders influenced the void structure and composition of the materials.
CERAMICS INTERNATIONAL
(2022)
Article
Materials Science, Multidisciplinary
Dongwon Lee, Yoon-Uk Heo, Jae Sang Lee, Won-Tae Cho, Unhae Lee, Myeong-Hun Kang, Chang Hee Yim
Summary: The role of AlN on the internal oxidation behavior in Al-containing high Mn steels was investigated. The results confirmed that increased Al contents led to accelerated internal oxidation. Sequential formation of internal oxidation and AlN + gamma-matrix layers was observed in the steel after heat treatment in air.
MATERIALS CHARACTERIZATION
(2022)
Article
Metallurgy & Metallurgical Engineering
Thi Thanh Tram Trang, Chang-Gon Jeong, Dongwon Lee, Yoon-Uk Heo
Summary: The effect of extended intercritical annealing time on the microstructure and tensile properties of a medium Mn steel is studied. Nanosized lamellar structures consisting of tempered-alpha ' martensite and retained austenite are formed after intercritical annealing. The fraction of cementite and fresh alpha ' martensite increases with extended annealing time, leading to reduced austenite fraction after quenching.
STEEL RESEARCH INTERNATIONAL
(2023)
Article
Metallurgy & Metallurgical Engineering
Fazlollah Sadeghi, Tahereh Zargar, Muhamad Rasyad Arkan Lahino, Hyeju Kim, Sang-Hum Kwon, Yoon-Uk Heo, Jae Sang Lee, Chang Hee Yim
Summary: The influence of reheating temperatures on hot ductility was investigated in two Ni-, Mo-, and Cu-containing low-carbon steels. It was found that higher reheating temperatures resulted in relatively poor hot ductility, while lower temperatures improved the ductility. In addition, the alloy composition and the existence of preformed precipitates were found to affect the hot ductility.
STEEL RESEARCH INTERNATIONAL
(2023)
Article
Materials Science, Multidisciplinary
Hyeonseok Kwon, Praveen Sathiyamoorthi, Manogna Karthik Gangaraju, Alireza Zargaran, Jaemin Wang, Yoon-Uk Heo, Stefanus Harjo, Wu Gong, Byeong-Joo Lee, Hyoung Seop Kim
Summary: In this work, a novel Fe-based medium-entropy alloy was designed based on the characteristics of maraging steels. By a single-step aging at 650 celcius for 10 min, the alloy exhibited microstructures consisting of high-density nanoprecipitates and reverted FCC phase, resulting in ultrahigh yield strength and good ductility.
Article
Chemistry, Physical
Eun Seong Kim, K. R. Ramkumar, G. M. Karthik, Sang Guk Jeong, Soung Yeoul Ahn, Praveen Sathiyamoorthi, Hyojin Park, Yoon-Uk Heo, Hyoung Seop Kim
Summary: In this study, the microstructural evolution, tensile properties, and deformation behavior of additively manufactured equiatomic CoCrFeMnNi high entropy alloy (HEA) were investigated at a cryogenic temperature of 77 K. The results showed that the HEA processed by direct energy deposition (DED) exhibited excellent strength and ductility at 77 K, with exceptional strain hardening, compared to the laser powder bed fusion (LPBF) and wrought samples. The formation of deformation twinning in addition to dislocation slip was observed as the deformation mechanism at 77 K.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Nanoscience & Nanotechnology
Gang Hee Gu, Yoon-Uk Heo, Hyeonseok Kwon, Soung Yeoul Ahn, Sujung Son, Peyman Asghari-Rad, Hyoung Seop Kim
Summary: Materials manufactured through conventional powder metallurgy techniques often have inferior tensile properties. However, a recently developed cold-consolidation technique using powder high-pressure torsion has produced well-manufactured structures with ultra-high tensile properties. In this study, the technique was used to fabricate a multi-material Inconel 718/CoCrFeMnNi/Inconel 718 layered structure, which exhibited superior tensile properties compared to monolithic systems. These findings demonstrate the potential of the cold-consolidation technique to manufacture multi-layered and gradient multi-functional structures with excellent mechanical response under tensile stress.
SCRIPTA MATERIALIA
(2023)
Article
Nanoscience & Nanotechnology
Rae Eon Kim, Gangaraju Manogna Karthik, Auezhan Amanov, Yoon-Uk Heo, Sang Guk Jeong, Gang Hee Gu, Hyojin Park, Eun Seong Kim, Do Won Lee, Hyoung Seop Kim
Summary: This study proposes a new strategy to achieve a superior gradient structure in 316L stainless steel fabricated by laser powder bed fusion (LPBF) through annealing and ultrasonic nanocrystal surface modification (UNSM). The post-LPBF annealing treatment disrupts the cellular dislocation structure, resulting in optimized materials for a gradient structure. The resulting gradient structure after UNSM treatment has a thicker gradient layer with significant strain partitioning between domains, leading to superior strength-ductility synergy compared to LPBF-UNSM samples.
SCRIPTA MATERIALIA
(2023)
Article
Materials Science, Multidisciplinary
T. T. T. Trang, Dongwon Lee, Yoon-Uk Heo
Summary: This study provides a detailed investigation of the twin structure in martensitic steels, clarifying the existence of ledge-typed twin boundaries at the {112} twin boundaries. The ledges occur on {110} planes and exhibit a gradual transition from the primary (112) twin plane to secondary twin planes (011) and (110).
Article
Chemistry, Physical
Minoru Maeda, Akiyoshi Matsumoto, Gen Nishijima, Yoon-Uk Heo, Seungyong Hahn, Sangjin Lee, Seyong Choi, Jung Ho Kim
Summary: In this study, the researchers proposed a method of regulating porous properties using magnesium powder blending. Through a detailed investigation, they found a significant correlation between various particle parameters, impurities, superconducting transition temperature, and current carrying capacity, with the porous properties. The blending of raw powders with spherical shape allowed for tuning of morphological structures and crystallinities inside the cores of the MgB2 superconducting wires, resulting in superior superconducting properties. This finding provides valuable insights for the widespread use and application of superconducting materials.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Materials Science, Multidisciplinary
Gang Hee Gu, Hyeonseok Kwon, Yongju Kim, Farahnaz Haftlang, Yoon-Uk Heo, Hyoung Seop Kim
Summary: Carbon-added equi-atomic CoCrFeMnNi high-entropy alloys exhibit bake hardening effect and show better performance compared to conventional bake-hardenable materials, providing possibilities for the industrialization of various interstitial HEA systems as well as carbon-added CoCrFeMnNi HEAs.
MATERIALS & DESIGN
(2023)
Article
Nanoscience & Nanotechnology
Chang-Gon Jeong, T. T. T. Trang, Youngyun Woo, Eun Yoo Yoon, Youngseon Lee, Yoon- Uk Heo
Summary: The effect of cooling rate on the microstructure and tensile properties of multiphase steel was investigated. Increasing the cooling rate significantly improved the tensile properties without sacrificing elongation, which was attributed to the increased fraction of bainite. All specimens exhibited similar fraction and mechanical stability of gamma.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Review
Microscopy
T. T. T. Trang, Yoon-Uk Heo
Summary: Nanosized precipitates are crucial for strengthening metallic alloys. The initial metastable precipitates in these alloys undergo a phase transition to stable phases during heat treatment, which can be studied using a transmission electron microscope.
Article
Nanoscience & Nanotechnology
Jeong Min Park, Hyeonseok Kwon, Jungho Choe, Kyung Tae Kim, Ji-Hun Yu, Yoon-Uk Heo, Hyoung Seop Kim
Summary: This study presents a guideline for alloy design in additive manufacturing, aiming to produce high-quality products with excellent mechanical performance by utilizing the unique segregation engineering of LPBF-driven microstructures. Mo-doping enhances the strength and ductility of ferrous medium-entropy alloys.
SCRIPTA MATERIALIA
(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.
