Article
Materials Science, Multidisciplinary
Hyeon-Woo Son, Sang-Hwa Lee, Sung-Ho Kang, Yong-You Kim, Kwangjun Euh
Summary: The effect of Ge addition on the delaying natural aging of Al-Mg-Si-Cu alloy was investigated. It was found that Ge addition suppressed the natural aging kinetics and cluster size. Atom probe tomography revealed that Ge refinement of cluster evolution was achieved by disturbing the magnesium enrichment of silicon-silicon clusters and enhancing vacancy trapping. Ge segregation at the cluster interface was also considered as a potential barrier to cluster growth.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2023)
Article
Materials Science, Multidisciplinary
Xia Chen, Dingfei Zhang, Yang Zhao, Fusheng Pan, Quanyi Liu
Summary: The study investigated the effect of microalloyed Ca on Mg-6Zn-1Mn-45n alloy, finding that the addition of calcium led to the formation of a new CaMgSn phase, suppressing the formation of Mg2Sn and improving the mechanical properties of the alloy.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2022)
Article
Chemistry, Physical
Vasile Avram, Ioana Csaki, Ileana Mates, Nicolae Alexandru Stoica, Alina-Maria Stoica, Augustin Semenescu
Summary: In this study, the structure and properties of an antifriction alloy YPbSn10 were improved using a microalloying technique. The results showed that the microalloying technique resulted in alloys with a homogeneous composition and a good distribution of the hard phase. Furthermore, the friction coefficient was reduced by almost 20% after microalloying.
Article
Materials Science, Multidisciplinary
Yichang Wang, Lingfei Cao, Xiaodong Wu, Xiaomin Lin, Tianyu Yao, Liming Peng
Summary: In this study, the effects of minor Ti, Mn, Cr, Zr, and Er additions on cast Al-Zn-Mg-Cu alloys were investigated. The addition of Ti significantly refines the ingot grains, while Mn and Cr additions reduce impurities and form specific phases. The joint addition of Ti, Mn, Cr, Zr, and Er creates a bulk composite phase. The alloy with the joint addition of these elements exhibits the highest hardness due to collaborative strengthening effects.
MATERIALS CHARACTERIZATION
(2023)
Article
Materials Science, Multidisciplinary
R. E. Schaublin, M. Becker, M. Cihova, S. S. A. Gerstl, D. Deiana, C. Hebert, S. Pogatscher, P. J. Uggowitzer, J. F. Loffler
Summary: The impact of Zn and Ca on the microstructure of lean Mg-Zn-Ca alloys was investigated. The precipitation of binary and ternary precipitates was observed at different temperatures. Hardness testing revealed that GP zones were the most effective factor in hardening.
Article
Materials Science, Multidisciplinary
Z. H. Li, D. Cheng, K. Wang, E. R. Hoglund, J. M. Howe, B. C. Zhouc, T. T. Sasaki, T. Ohkubo, K. Hono
Summary: This study investigated the precipitation process of a Mg-0.3Ca-0.6Zn alloy during isothermal aging at 200 degrees C using advanced microscopy techniques and first-principles calculations. The results revealed the formation of monolayer G.P. zones, which transformed into tri-atomic layer η'' and η' plates. The η' plates then formed pairs and stacks with pure magnesium layers. The unique structure of coarse η1 plates led to a different precipitate microstructure evolution from other Mg-RE-Zn alloys. First-principles calculations confirmed the crystal structure and stability of the precipitates, supporting a new precipitation sequence.
Article
Nanoscience & Nanotechnology
Z. Ma, J. D. Robson
Summary: Al-Zn-Mg-Cu alloys achieve high strength mainly through precipitation strengthening. This study investigated the coupling of dislocation and precipitation strengthening in pre-aged AA7075 alloys to achieve strengths greater than those obtained with heat treatment alone. The results showed that deformation introduced sufficient dislocations for work hardening and post-ageing at 120 degrees C was effective in promoting precipitation strengthening. The time required to reach peak strength is determined by the competition between precipitation kinetics and dislocation recovery.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Materials Science, Multidisciplinary
Risheng Pei, Yongchun Zou, Muhammad Zubair, Daqing Wei, Talal Al-Samman
Summary: This study investigates the synergistic effect of various alloying elements on the texture and microstructure evolution in magnesium alloys. The results demonstrate that adjusting the precipitation and solute segregation can lead to desired texture modifications.
Article
Nanoscience & Nanotechnology
Mouxin Wu, Jihua Chen, Hongge Yan, Weijun Xia, Bin Su, Yifu Deng, Yu Shen
Summary: This study investigated the effect of Ca concentration on the microstructure, mechanical properties, and thermal conductivity of Mg-2Ga-xCa (x = 0, 0.2, 0.4, and 0.8 wt.%) alloys at room temperature. Increase in Ca content led to a decrease in grain size and volume fraction of recrystallized grains, resulting in increased yield strength. However, it also caused an increase in the number and size of second phase particles, leading to reduced plasticity. Minor Ca additions (0.2% and 0.4%) had no significant effect on thermal conductivity, but 0.8% Ca addition significantly improved the thermal conductivity of both as-cast and as-extruded alloys. The as-extruded Mg-2Ga-0.8Ca alloy exhibited a tensile yield strength of 244 MPa and a thermal conductivity of 135.5 W·m-1·K-1. It is suggested that Mg alloys with high strength and high thermal conductivity can be designed by selecting appropriate alloying elements to form precipitates instead of dissolving in the Mg matrix.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Nanoscience & Nanotechnology
Lingbao Ren, Carl J. Boehlert, Gaofeng Quan
Summary: The study found that adding different ratios of yttrium and neodymium to the AZ80 alloy under different temperature and stress conditions can affect the tensile creep behavior and microstructural evolution of the alloy, resulting in lower tensile strength and elongation but higher creep resistance. The secondary creep deformation mechanism was suggested to be pipe-diffusion-assisted dislocation creep, and the occurrence of discontinuous precipitation was impeded by precipitate-containing twins in the alloys containing yttrium and/or neodymium.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Materials Science, Multidisciplinary
Xinyu Sun, Chuncheng Ge, Chubin Yang, Dongdong Zhang, Jingren Li, Dongsheng Xie, Hucheng Pan, Gaowu Qin
Summary: In this study, the microstructure and mechanical properties of Mg alloys were investigated. It was found that specific combinations of alloys can achieve ultra-high strength and high thermal stability. The deformed grains and residual dislocation density during extrusion, as well as the nano-precipitates induced by manganese addition, play important roles in the performance of the alloys.
MATERIALS CHARACTERIZATION
(2022)
Article
Metallurgy & Metallurgical Engineering
Chang Liu, Qing Wang, Bin Han, Junhua Luan, Ji-Jung Kai, Chain-Tsuan Liu, Ge Wu, Jian Lu
Summary: Dual-phase metallic glasses with nanostructured Ca-rich amorphous phases exhibit a dense corrosion layer that protects the material from further corrosion, resulting in a corrosion rate 77% lower than pure Mg.
JOURNAL OF MAGNESIUM AND ALLOYS
(2021)
Article
Metallurgy & Metallurgical Engineering
Hewei Chen, Bo Yuan, Rui Zhao, Xiao Yang, Zhanwen Xiao, Antoniac Aurora, Bita Ana Iulia, Xiangdong Zhu, Antoniac Vasile Iulian, Xingdong Zhang
Summary: Alloying treatment is an effective method to regulate the degradation rate of magnesium-based materials. In this study, three magnesium alloys were fabricated and evaluated for their corrosion resistance and degradation rate. The addition of zinc and silver enhanced the antibacterial potential of the magnesium alloys. In vitro cell experiments demonstrated the good biocompatibility of these alloys.
JOURNAL OF MAGNESIUM AND ALLOYS
(2022)
Article
Chemistry, Physical
Changwei Gong, Xinze He, Daqing Fang, Baosheng Liu, Xue Yan
Summary: The study investigates the impact of second phases on discharge properties and corrosion behaviors of as-cast Mg-Ca-Zn anodes for primary Mg-air batteries. Results show that the Mg-2Zn-1Ca alloy has the best discharge properties among all prepared Mg-Ca-Zn alloys.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Metallurgy & Metallurgical Engineering
N. Pulido-Gonzalez, P. Hidalgo-Manrique, S. Garcia-Rodriguez, B. Torres, J. Rams
Summary: The effect of heat treatment on the mechanical and biocorrosion behavior of Mg-Zn-Ca alloys was investigated. The results showed that the thermal conditions significantly affected the microstructure and corrosion properties of the alloys.
JOURNAL OF MAGNESIUM AND ALLOYS
(2022)
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)
Editorial Material
Materials Science, Multidisciplinary
Satoshi Hirosawa, Kazuhiro Hono
SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS
(2022)
Article
Physics, Applied
Tomohiro Ichinose, Tatsuya Yamamoto, Jun Uzuhashi, Takayuki Nozaki, Tadakatsu Ohkubo, Kay Yakushiji, Shingo Tamaru, Kazuhiro Hono, Shinji Yuasa
Summary: Thermally robust perpendicular magnetic anisotropy and voltage-controlled magnetic anisotropy effects were achieved in magnetic tunnel junctions with ultrathin CoFeB films by utilizing Ta/Mo layered adhesion structures.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Applied
Jun Uzuhashi, Jun Chen, Ashutosh Kumar, Wei Yi, Tadakatsu Ohkubo, Ryo Tanaka, Shinya Takashima, Masaharu Edo, Kacper Sierakowski, Michal Bockowski, Hideki Sakurai, Tetsu Kachi, Takashi Sekiguchi, Kazuhiro Hono
Summary: An investigation on annealing under different conditions after magnesium (Mg) implantation into GaN crystals revealed that ultra-high-pressure annealing (UHPA) effectively suppresses the formation of Mg-enriched defects, leading to improved p-type activation efficiency.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Kresna B. Fathoni, Zehao Li, Tomoya Nakatani, Yuya Sakuraba, Taisuke Sasaki, Kazuhiro Hono
Summary: The MR ratio of CoFe/bcc-Cu/CoFe CIP-GMR devices grown on Si(0 0 1) substrate is slightly lower than that grown on MgO(0 0 1) substrate due to the presence of fcc phase of Cu.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
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
Ivan Kurniawan, Yoshio Miura, Kazuhiro Hono
Summary: In this study, we propose a new type of half-metallic Heusler alloy material based on finite-temperature first-principles calculation using the disordered local moment method and machine learning. This material addresses the issue of large degradation in magnetoresistance ratio at room temperature and several prospective materials were identified.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Chemistry, Physical
N. Banjo, T. T. Sasaki, K. Hono
Summary: In this study, the conditions for achieving impact adhesion and salt spray corrosion resistance equivalent to chromate conversion coatings on extruded A6063 alloy were investigated. The microstructure of titanium-based conversion coatings was also observed. By densely dispersing titanium-oxide particles of 20-50 nm thick on the aluminum matrix, the same performance as chromate conversion coatings was achieved.
APPLIED SURFACE SCIENCE
(2022)
Article
Physics, Applied
Zixi Chen, Yuya Sakuraba, Yoshio Miura, Zehao Li, Taisuke Sasaki, Hirofumi Suto, Varun K. Kushwaha, Tomoya Nakatani, Seiji Mitani, Kazuhiro Hono
Summary: This study investigates the effects of off-stoichiometric compositional variations on the electronic structure of the Co2Fe(Ga0.5Ge0.5) full-Heusler alloy. First-principles calculations predict that Co-Fe defects introduce a finite density of states in the half-metallic gap, while Fe-Co defects preserve the gap but reduce spin polarization. Experimental results confirm that Ge-excess in Fe-excess CFGG enhances spin polarization. By adjusting the Fe and Ge compositions, the formation of secondary phases can be suppressed.
JOURNAL OF APPLIED PHYSICS
(2022)
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
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.
Proceedings Paper
Engineering, Mechanical
Suhas Eswarappa Prameela, Taisuke Sasaki, Peng Yi, Michael Falk, Kazuhiro Hono, Timothy P. Weihs
MAGNESIUM TECHNOLOGY 2022
(2022)
Article
Chemistry, Physical
A. K. Srinithi, H. Sepehri-Amin, Y. Takagiwa, K. Hono
Summary: This study investigates the microstructural factors controlling the electrical conductivity in p-type Fe3Al2Si3-based thermoelectric materials. The formation of a composite structure consisting of FeSi precipitates dispersed in the tau(1)-matrix is found to increase the electrical conductivity while maintaining thermal conductivity and sufficiently high Seebeck coefficient. The control of the tau(1)-Fe3Al2Si3/E-FeSi composite microstructure is critical to developing a higher power factor in p-type FAST materials.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
