Article
Chemistry, Physical
Qingfang Huang, Qingzheng Jiang, Yao Shi, Sajjad Ur Rehman, Xing Wei, Zhixiang Li, Dawei Shi, Deqin Xu, Zhenchen Zhong
Summary: Post-sinter annealing is crucial for improving the microstructures and magnetic properties of NdFeB-based sintered permanent magnetic materials. It can significantly increase the intrinsic coercive force of the magnets. However, post-sinter annealing may cause a slight decrease in remanence, mainly due to the deteriorated orientation degree and reduced volume fraction of the hard magnetic main phases.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Chemistry, Physical
Zhehuan Jin, Guangfei Ding, Xiaodong Fan, Shuai Cao, Sining Fan, Zhixiang Wang, Bo Zheng, Shuai Guo, Renjie Chen, Aru Yan, Xincai Liu
Summary: The grain boundary diffusion process of Pr-Al-Cu at various temperatures in sintered Nd-Fe-B magnets and its influence on the magnetic properties were investigated. The results showed that the diffusion process resulted in the formation of shell phases rich in Pr and Al at 700 degrees C, which significantly enhanced the coercivity of the magnets after annealing. The thickness of the shell phase decreased during the annealing process and facilitated the formation of intergranular phases.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Materials Science, Multidisciplinary
Qingfang Huang, Qingzheng Jiang, Yao Shi, Sajjad Ur Rehman, Dawei Shi, Gang Fu, Zhixiang Li, Deqin Xu, Dakun Chen, Zhenchen Zhong
Summary: This paper investigates the influence of Gallium (Ga) doping on the microstructure, thermal stability, and magnetic properties of NdFe-B based sintered magnets. It is found that the addition of Ga significantly increases the intrinsic coercivity while slightly decreasing the remanence. The Ga-doped sample also exhibits better thermal stability. Microstructural analysis shows that the addition of Ga promotes the diffusion of Nd and Cu, resulting in changes in the grain boundary phase and Fe concentration. Additionally, the Curie temperature increases after Ga doping.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Article
Chemistry, Physical
Sining Fan, Mengxin Jin, Guangfei Ding, Xiaodong Fan, Shuai Guo, Bo Zheng, Renjie Chen, Aru Yan, Bin Meng
Summary: The grain boundary in B-lean Nd-Y-Fe-B multi-main-phase (MMP) magnets was modified by the addition of Pr64Fe12Al9Ga15. The addition of 2 wt% Pr64Fe12Al9Ga15 resulted in a significant increase in coercivity, while further increases in additive content did not affect the coercivity. The formation of RE6Fe13(Ga, Al)1 contributed to the optimization of the grain boundary phase distribution and strengthened the magnetic isolation between grains. However, excessive additive content caused the agglomeration of RE6Fe13(Ga, Al)1 in the triple junction region, leading to a reduction in remanence.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Materials Science, Multidisciplinary
Xia Ding, Xiu-Chun Wang, Kai-Hong Ding, Sheng-Li Cui, Yong-Cong Sun, Mu-Sen Li
Summary: The corrosion-resistant coating formed by phosphate chemical conversion treatment on sintered Nd-Fe-B magnets significantly improves their corrosion resistance without compromising magnetic properties, providing an effective way to enhance the corrosion resistance of these magnets.
Article
Materials Science, Multidisciplinary
J. S. Zhang, Xin Tang, H. Sepehri-Amin, A. K. Srinithi, T. Ohkubo, K. Hono
Summary: An anisotropic bulk SmFe12-based sintered magnet with high coercivity and remanence ratio has been successfully prepared using a conventional liquid sintering process. The magnet consists mainly of Sm(Fe,Ti,V,Al)(12) grains with a ThMn12-type crystal structure and a Sm-rich amorphous intergranular phase. Further research is needed to reduce grain size and engineer the intergranular phase composition to improve coercivity.
Article
Chemistry, Physical
Feifei Li, Jiajie Li, Sajjad Ur Rehman, Lili Zhang, Yikuan Hu, Munan Yang, Xiaoqiang Yu, Shuwei Zhong, Tongxiang Liang
Summary: By utilizing composite powders for grain boundary diffusion, a significant improvement in coercivity of magnets can be achieved, while optimizing the microstructure can enhance the temperature coefficient of coercivity. Improved Pr-Al-rich grain boundary phases contribute to excellent diffusion efficiency and Dy diffusion depth.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Chemistry, Applied
Ze Duan, Haicheng Xuan, Jincai Su, Jingwu Chen, Xiaofei Yi, Youhao Liu, Peide Han
Summary: By adding Tb80Fe20 alloy into the Nd-Fe-B sintered magnets, the coercivity and thermal stability of the magnets can be significantly improved. The addition of 4 wt% Tb80Fe20 alloy increases the coercivity and decreases the remanence of the magnets, as well as improves the reversible temperature coefficients of coercivity and remanence in the temperature range of 20-170 degrees Celsius. Moreover, the addition of Tb80Fe20 alloy reduces the irreversible flux magnetic loss and improves the microstructure of the magnets.
JOURNAL OF RARE EARTHS
(2022)
Article
Chemistry, Applied
Yilong Ma, Qiqi Yang, Xiaoli Chen, Ying He, Wenbo Xiang, Jiaqi Lai, Bin Shao, Donglin Guo, Dengming Chen, Kejian Li
Summary: The addition of Ce-Co alloy can significantly increase the coercivity of Nd-Fe-B bulk alloy, but the density of the magnet reaches a maximum value at a certain concentration, with the coercivity increasing slowly. Moreover, extending the sintering holding time facilitates the diffusion of Ce-Co into the Nd-Fe-B matrix, enhancing the coercivity of the magnet.
JOURNAL OF RARE EARTHS
(2021)
Article
Chemistry, Applied
Xiaolian Liu, Mengjie Pan, Pei Zhang, Tianyu Ma, Lizhong Zhao, Lingwei Li
Summary: Homogeneous substitution of Dy for Nd in the 2:14:1 phase can enhance coercivity but reduce remanence. A comparative study showed that multi-main-phase magnet with inhomogeneous Dy distribution has better magnetic properties and thermal stability than single-main-phase magnet with homogeneous Dy distribution. The multi-main-phase magnet exhibited higher coercivity, remanence, and energy product at room temperature and over a wide temperature range.
JOURNAL OF RARE EARTHS
(2021)
Article
Materials Science, Multidisciplinary
Z. Wang, T. T. Sasaki, Y. Une, T. Ohkubo, K. Hono
Summary: Record-breaking high coercivity is achieved in Dy-free sintered magnets by separately diffusing Dy70Cu30 and Pr68Cu32 eutectic alloys. The low Dy content sample exhibits a high coercivity of 2.8 T and an excellent temperature coefficient of coercivity. The unique presence of a uniform Dy-rich shell and enriched Pr near the surface of Nd2Fe14B grains strengthens the anisotropy field, resulting in the high coercivity without alloying Dy to the initial magnet.
Article
Nanoscience & Nanotechnology
F. Bittner, J. Thielsch, W. -G. Drossel
Summary: Additive manufacturing of Nd-Fe-B permanent magnets through laser powder bed fusion (LPBF) achieves high remanence and maximum energy product without the need for additional Nd-rich low-melting alloys or post-treatments, leading to the highest reported values for additively manufactured permanent magnets. The isotropic microstructure consists of short Nd2Fe14B dendrites and globular sub-micron sized grains, with no evidence of alpha-Fe after LPBF of the Nd-lean powder.
SCRIPTA MATERIALIA
(2021)
Article
Materials Science, Multidisciplinary
Zhixiang Wang, Sining Fan, Jinhao Zhu, Bo Zheng, Guangfei Ding, Shuai Guo, Renjie Chen, Aru Yan, Mingang Zhang, Jingdong Guo, Baohua Zhang
Summary: Diffusing a Ga-containing Nd-Fe-B magnet with Pr70Fe30 alloys can increase its coercivity and improve the grain boundary structure.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Review
Materials Science, Multidisciplinary
Keiko Hioki
Summary: This study focused on the magnetic properties of hot-deformed anisotropic Nd-Fe-B magnets, improving the hot-deformation technique and optimizing microstructure to fabricate high-performance magnets.
SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
Shuai Cao, Xiaoqian Bao, Xinfang Song, Chi Zhang, Xiaoshuang Yan, Jiheng Li, Xuexu Gao
Summary: The commercial N50 Nd-Fe-B magnet underwent a combined diffusion process with Pr65Cu15Al20 and Pr50Tb30Al20, resulting in an increase in coercivity and the formation of uniform Tb-rich shells. The combined diffusion process proved effective in promoting Tb diffusion along grain boundaries and enhancing Tb availability.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2021)
Article
Physics, Applied
Kresna B. Fathoni, Yuya Sakuraba, Yoshio Miura, Taisuke Sasaki, Tomoya Nakatani, Kazuhiro Hono
Summary: The study indicates that in order to enhance the magnetoresistance ratio in CIP-GMR using half-metallic materials, it is crucial to match the resistivity between the ferromagnetic layers and the nonmagnetic layer, in addition to considering the high electronic band matching as a key factor to achieve high MR ratio in CIP-GMR devices.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Xin Tang, H. Sepehri-Amin, A. Bolyachkin, T. Ohkubo, K. Hono
Summary: This study explores the potential of low-cost (Nd,La,Ce)-Fe-B hot deformed magnets for the application in variable-magnetic-force (VMF) motors. The results show that the hot-deformed magnets have the ability to adjust the coercivity and exhibit flat reversal curves. The microstructure observation and magneto-optical Kerr effect microscopy reveal the origin of the flat reversal curves. Additionally, the hot-deformed magnets have a relatively high remanent magnetization compared to sintered magnets, making them excellent candidates for VMF motor applications.
Article
Materials Science, Multidisciplinary
H. Sepehri-Amin, Xin Tang, T. Ohkubo, K. Hono
Summary: Understanding the magnetization reversal processes of permanent magnets is essential for developing magnets with high coercivity. Recent studies have used magneto-optical Kerr effect microscopy to observe the dynamic magnetic domains under an external magnetic field. Different microstructural features, such as grain boundaries and interfaces, influence the magnetization reversal processes of Nd-Fe-B-based permanent magnets. By manipulating these factors, it is possible to achieve magnets with higher coercivity.
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
Microscopy
Sujin Lee, Atsuko Sato, Takehiro Tamaoka, Kunio Yubuta, Mitsunari Auchi, Taisuke Sasaki, Tadakatsu Ohkubo, Kazuhiro Hono, Yasukazu Murakami
Summary: This paper proposes a method using electron holography to provide a phase image of the demagnetization field (H-d) within a thin-foil permanent magnet. The observation of H-d remains challenging because electron holography can only image the magnetic flux density (B), which is a combination of contributions from magnetization (M), stray magnetic field (H-s) outside the specimen, and H-d inside the specimen. The phase map approximating H-d, determined from electron holography observation of a Nd2Fe14B single-crystalline specimen, shows good agreement with micromagnetic theory's prediction. This method can be applied to study the coercivity mechanism of permanent magnets, which is sensitive to the demagnetization field.
Article
Materials Science, Multidisciplinary
Peng Yi, Taisuke T. Sasaki, Suhas Eswarappa Prameela, Timothy P. Weihs, Michael L. Falk
Summary: Atomic-scale calculations indicate that both stress effects and chemical binding contribute to solute redistribution in the presence of vacancy clusters in magnesium alloys. The size of the vacancy cluster influences the importance of chemical binding relative to stress. These solute-vacancy interactions also affect the diffusivity of vacancies and vacancy clusters in a solid solution. Experimental observations in Mg-Al alloys support the role of solute segregation in simultaneously deformed and aged samples.
Article
Materials Science, Multidisciplinary
D. Xie, Z. H. Li, T. T. Sasaki, Y. F. Gao, Z. Y. Lyu, R. Feng, Y. Chen, K. An, H. B. Chew, T. Nakata, S. Kamado, K. Hono, P. K. Liaw
Summary: The low-alloyed Mg-Al-Ca-Mn alloy, as a new class of heat-treatable magnesium alloys, shows great engineering potential due to its excellent extrudability and high strength achieved by the dispersion of Guinier-Preston (G.P.) zones. In this study, in situ neutron diffraction measurements were conducted to investigate the cyclic deformation behavior of this alloy with and without G.P. zone dispersion. The relationship between macroscopic deformation behavior and microscopic response at the grain level, such as twinning and detwinning, was established.
Article
Materials Science, Multidisciplinary
Z. Wang, T. T. Sasaki, Y. Une, T. Ohkubo, K. Hono
Summary: Record-breaking high coercivity is achieved in Dy-free sintered magnets by separately diffusing Dy70Cu30 and Pr68Cu32 eutectic alloys. The low Dy content sample exhibits a high coercivity of 2.8 T and an excellent temperature coefficient of coercivity. The unique presence of a uniform Dy-rich shell and enriched Pr near the surface of Nd2Fe14B grains strengthens the anisotropy field, resulting in the high coercivity without alloying Dy to the initial magnet.
Article
Chemistry, Physical
Z. H. Kautsar, H. Sepehri-Amin, Xin Tang, R. Iguchi, K. Uchida, T. Ohkubo, K. Hono
Summary: The resistivities of anisotropic Nd-Fe-B-based magnets were increased in parallel and perpendicular directions to the c-axis by hot-deforming Nd-Fe-B melt-spun flakes coated with DyF3 through electrophoretic deposition. As a result, the operating temperature under high-frequency AC magnetic field decreased by 20°C due to the reduction of eddy current loss. The formation of a resistive layer composed of NdF3 at the interface of original ribbons in the hot-deformed magnet was observed. The excess Dy diffused into the original ribbon flakes and formed a Dy-rich shell in Nd2Fe14B grains, resulting in a high coercivity.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Microscopy
Jun Uzuhashi, Tadakatsu Ohkubo, Kazuhiro Hono
Summary: Atom probe tomography (APT) is a widely used technique for analyzing the microstructure of alloys and devices. In this study, a method for automatically fabricating the desired tip shape using a script-controlled FIB-SEM system was developed. The effect of intentionally changing the tip shape on APT data was also discussed.
Article
Materials Science, Multidisciplinary
Yusuke Kozuka, Taisuke T. Sasaki, Terumasa Tadano, Jun Fujioka
Summary: In this study, the fabrication and transport properties of SrPd3O4 and CaPd3O4 thin films as candidates of oxide Dirac semimetals are investigated. The observed weak temperature dependence suggests narrow-gap properties, but unintentionally doped holes hinder the discovery of the Dirac band. The study establishes the basic thermodynamics of thin-film fabrication and paves the way for exploring interesting properties of topological band structures.
SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS
(2023)
Article
Nanoscience & Nanotechnology
J. J. Bhattacharyya, T. T. Sasaki, T. Nakata, S. R. Agnew
Summary: This study explains why rolled sheet material is softer and less responsive to aging compared to extruded material. By using crystal-plasticity modeling, it is shown that the initial texture of the rolled material allows for the accommodation of soft modes, such as basal slip and twinning, during in-plane tension. These modes are less affected by the finely dispersed Guinier-Preston (GP) zones, even with the same number density. In contrast, the extruded material is stronger in tension along the extrusion axis due to a higher relative activity of prismatic slip, which is strongly affected by the GP zones. This study emphasizes the significant role of initial texture in determining the strength and anisotropy of non-cubic metals and alloys.
SCRIPTA MATERIALIA
(2023)
Article
Materials Science, Multidisciplinary
Ryo Toyama, Satoshi Kokado, Keisuke Masuda, Zehao Li, Varun K. Kushwaha, Taisuke T. Sasaki, Loku Singgappulige Rosantha Kumara, Tomoyuki Koganezawa, Hiroo Tajiri, Takahiro Yamazaki, Masato Kotsugi, Yuma Iwasaki, Yuya Sakuraba
Summary: In this paper, the origin of the anisotropic magnetoresistance (AMR) effect in thin films is investigated through experimental observation and theoretical modeling. It is found that the addition of Ir atoms leads to a sign change in the AMR ratio, with the highest negative values observed at high Ir concentrations. The theoretical model confirms that this sign change is due to the B2 ordering phase. These findings provide insights into the AMR origin in heavy-metal-doped ferromagnetic alloys.
PHYSICAL REVIEW MATERIALS
(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.
