Papers by Author: Susumu Ikeno

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Authors: Seiji Saikawa, Chiharu Otsubo, Susumu Ikeno, Koichi Komai
Abstract: Al-Li alloys have higher mechanical properties and more lightweight than other conventional aluminum alloys. Therefore , it is focused as a good material for weight reduction of industrial fields. However, since the Al-Li alloy are highly active and hard to cast, there has been limited research on casting. In this study, age-hardening behavior of Al-2.5mass%Li alloys cast into sand and metal mold were investigated. All alloys cast into Y-block shape sand mold, and then artificial aged after solution treated at 743K for 36ks. Because of difference in quantity of precipitation by metastable δ’(Al3Li) phase, peak hardness of metal mold casting is higher than that of sand molds castings.
Authors: Azusa Furihata, Kenji Matsuda, Junya Nakamura, Susumu Ikeno, Yasuhiro Uetani
Abstract: In this work, the age-hardening of Al- 1.0 mass% Mg2Si- 0.4 mass% Mg – 0.5 mass% Ag (ex.Mg-Ag alloy) alloy has been investigated. It showed increase of hardness and age-hardening response. Precipitates in this alloy aged at 523 K have been observed by high resolution transmission electron microscopy (HRTEM) and classified into five types based on characteristics in their HRTEM images.
Authors: Tomoatsu Murakami, Kenji Matsuda, Takeshi Nagai, Junya Nakamura, Tokimasa Kawabata, Susumu Ikeno
Abstract: It is known that Al-Mg-Ge alloy shows the similar precipitation sequence to Al-Mg-Si alloy, and its equilibrium phase is β-Mg2Ge according to its phase diagram. In this study, the precipitation sequence of Al-Mg-Ge alloys containing different contents of Mg2Ge has been investigated by hardness test, TEM and HRTEM observation to understand the effect of Mg2Ge contents on age-hardening behavior of the alloys. The hardness of as-quenched and peak-aged samples have been improved by increasing Mg2Ge contents. The precipitates in the peak-aged samples have been classified into some metastable phases, such as the β’-phase and parallelogram-type precipitate by HRTEM observation. The relative frequency of these precipitates in the is has been changed with Mg2Ge contents.
Authors: Masaya Nishikubo, Kenji Matsuda, Yoshihisa Oe, Jyunya Nakamura, Susumu Ikeno
Abstract: In this study, the aging behaviour of several Al-Mg-Si alloys (Al-Mg-Si-Cu , Al-Mg-Si-Ag and Al-Mg-Si-Cu-Ag) has been investigated by hardness tests and TEM observations. Comparing the age-hardening rate in the early period of these alloys, the alloys with Cu or/and Ag addition are faster than that of the base alloy, and the aging time to reach the maximum hardness of the alloys with Cu or/and Ag addition is shorter than that of the base alloy.Therefore the aging behaviour of that alloys has been investigated by TEM observations to understand the effect of Cu, Ag and Cu+Ag additions on aging precipitation.
Authors: Kaname Fujii, Tokimasa Kawabata, Kenji Matsuda, Susumu Ikeno
Abstract: Changes in the mechanical properties on AZ91 Mg alloy cast into sand mold caused by heat-treatment and its microstructure were investigated by the tensile test and observation using optical and scanning electron microscopes, and chemical composition analysis. Tensile test results show that the specimens aged at 441K have larger elongation than those of aged at 489K, although they had same proof stress. The fracture surface observation reveal the cleavage fracture of aged specimen caused by the nodular structure as well as the formation of micro void around the coarse spheroidal Al-Mn-(Fe) phase.
Authors: Kenji Matsuda, Susumu Ikeno, Tatsuo Sato, Akihiko Kamio
Authors: Kenji Matsuda, Junya Nakamura, Yoshio Nakamura, Tatsuo Sato, Susumu Ikeno
Abstract: The crystal structure of metastable phase in Ag added Al-Mg-Si alloy was investigated by comparing the β’-phases in Al-Mg-Si alloy without Ag, using images of high resolution transmission electron microscope (HRTEM), selected area electron diffraction patterns (SADPs) and an energy dispersive X-ray spectroscopy (EDS). SADPs and HRTEM images obtained from metastable phase in the Ag added Al-Mg-Si alloy showed similar to those of β’-phase in Al-Mg-Si alloy without Ag and had different lattice spacings because of the effect of Ag. According to our careful analysis on obtained HRTEM images and SADPs, it includes more complicated crystal lattice of distorted hexagons.
Authors: Katsumi Watanabe, Kenji Matsuda, Tokimasa Kawabata, Susumu Ikeno
Abstract: Magnesium alloys have received considerable attention because of their lightweight and recyclability. AM-series and AZ-series Mg-Al alloys have been used for industrial products widely, particularly for AM-series alloys because of better toughness and impact absorption properties than AZ-series alloys. The Mg17Al12 intermetallic compound is the only precipitate formed during ageing after the solution heart treatment. Discontinuous precipitates exist in grain boundary randomly, and continuous precipitates exist in the matrix. However, there is few report about the orientation relationship between the discontinuous precipitates and the matrix. The purpose of this study is to investigate the orientation relationship between the discontinuous precipitates and the matrix of AM-series magnesium alloys. Hardness measurement, SEM observation, the electron backscattered diffraction (EBSD) techniques were preformed in order to understand the relationship between the discontinuous precipitate and crystallographic orientation of grains in AM-series magnesium alloy. TEM samples with discontinuous precipitates were prepared using the focused ion beam (FIB). And TEM observation was performed to investigate the discontinuous precipitates and crystallographic orientation in the matrix.
Authors: Masahiro Shinsen, Mitsuaki Furui, Susumu Ikeno, Takekazu Nagae
Abstract: In present work, bar samples of pure copper and Cu-Zn alpha single phase alloys setting 20mm in diameter and 150mm in length processed by torsion in the rotation speed to 1rpm every 60° twist angles. Then, deformed samples were researched microstructure and their characteristics. Microstructures of non-deformation samples were isometric, however, deformed samples streaky. Elements of bar drawn 10×10mm mesh were developed parallelogram. It was trend angle of between stretchable direction in microstructures and torsion axis increased more torsion angles. It was coincident with between the angle and deformed direction of microstructures. Shear strain was calculated by twist angle by theoretical formula. Their value corresponded rough with measurement from mesh variation. Pure copper and Cu-Zn alpha phase alloys were similar deformation microstructure, but fracture twist angle in copper was more than Cu-Zn alloys, and it was trend fracture angle had decreased as concentration of Zn increased. This trend was difference of fracture elongation obtained in tensile test.
Authors: Yuhei Ebata, Mitsuaki Furui, Susumu Ikeno, Katsuya Sakakibara, Seiji Saikawa
Abstract: In this study, age-hardening behavior of Mg-Xmass%Al alloys (X=3, 4.5, 6, 7.5 and 9mass%) were investigated by Vickers hardness measurement and optical microscopic observation. Each alloy was solution-treated and then isothermal-aged at 473, 498 and 523K. In the case of aluminum content less than 6mass%, Mg-3mass%Al and Mg-4.5mass%Al alloys, occurred insignificant age hardening. In the case of aluminum content higher than 6mass%, Mg-6mass%Al, Mg-7.5mass%Al and Mg-9mass%Al alloys, occurred remarkable age hardening. For each aging temperature, with heighten aluminum content, increase the value of maximum hardness and shorten time to maximum hardness. Mean hardness of discontinuous precipitation during aging increased with lower aging temperature and higher aluminum content. Furthermore, over-aged microstructure of Mg-Al system alloys differed from aluminum content or aging temperature.
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