Papers by Author: Tohru Yamasaki

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Authors: Takeshi Fukami, M. Fukatani, Daisuke Okai, Tohru Yamasaki, Osami Haruyama, Akihisa Inoue
Abstract: In order to examine the correlation between a mechanical property and an excess free volume for metallic glass Pd44Cu31Ni8P17, longitudinal and transverse ultrasonic velocities were measured to estimate longitudinal and transverse elastic constants, c11 and c44. An as-quenched sample, an annealed one at a temperature just below a glass transition temperature Tg and a crystalline one were prepared. The as-quenched sample contains the excess free volume depending on the preparing process. The Young’s modulus E, the Poisson’s ratio, a bulk modulus and c12 are estimated using c11 and c44. The values of c11, c 44 , c12 and E of the as-quenched one are smaller than those of the annealed sample losing excess free volume by about 0.2 % and much smaller than those of the crystalline one. The Poisson’s ratio for the as-quenched sample and the annealed one are 0.389 and 0.387, respectively, which are much larger than that for the crystalline one with 0.349.
Authors: Masahiro Komaki, Tsunehiro Mimura, Yuji Kusumoto, Ryurou Kurahasi, Masahisa Kouzaki, Tohru Yamasaki
Abstract: Some amorphous Fe-Cr-P-C coating films having high hardness and high corrosion resistance have been produced by a newly developed thermal spraying technique. In order to control the temperatures of the powder particles in the flame spray and the substrate, a newly developed cylindrical nozzle, with external cooling nitrogen gas, was mounted to the front end of the thermal spray gun. Fe70Cr10P13C7 films with various external cooling gas velocities between 20 m/s and 40 m/s exhibited entire amorphous structure without oxides and/or unmelted particles. Corrosion-resistance of the films was observed in immersion tests using various corrosive liquids.
Authors: Hiroyuki Matsuoka, Takako Okada, Tohru Yamasaki, Takeshi Fukami
Authors: Y.J. Zheng, Tohru Yamasaki, Mititaka Terasawa, Tohru Mitamura, Takeshi Fukami
Authors: Tohru Yamasaki, Y. Demizu, Y. Ogino
Authors: Fujita Kazutaka, Taiji Suidu, Tohru Yamasaki
Abstract: The tensile specimen of nanocrystalline Ni–W alloys with 50 μm × 20 μm in area and 4 mm in gauge length was made by using an electrodeposit together with ultraviolet light lithographic technique. The composition and grain size were Ni-16.9 at.% W and about 6 nm, respectively. Tensile testing of the alloy was carried out. The nominal tensile strength and Young’s modulus were about 2.7 GPa and 123 GPa, respectively. The elastic strain and plastic strain were about 2 % and 1 %, respectively. The stress-strain curve showed work hardening. The macroscopic fracture part yielded necking and the microscopic fracture surface showed dimple pattern. As mentioned above, this electrodeposited nanocrystalline Ni-W alloy showed high strength, low elastic modulus and high ductility.
Authors: Natsuko Oda, Hiroyuki Matsuoka, Tohru Yamasaki, Takeshi Fukami
Authors: Toshio Nasu, Masaki Sakurai, Tomoaki Kamiyama, Takeshi Usuki, Kazuto Tokumitsu, Tohru Yamasaki
Authors: Tohru Yamasaki, P. Schloßmacher, K. Ehrlich, Y. Ogino
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