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Featured researches published by Naoya Sasaki.
Transactions of the Japan Society of Mechanical Engineers. A | 1996
Tomio Iwasaki; Naoya Sasaki; Akio Yasukawa; Norimasa Chiba
Grain boundary grooving in crystalline aluminum is simulated by computer molecular dynamics, and impurity effects are investigated. We use a Morse potential that includes equilibrium spacing, γA1, and potential well depth, |uA1| to characterize aluminum-aluminum interaction. We also use a two-body interatomic potential that includes equilibrium spacing, γm, and potential well depth, |umin| to characterize aluminum-impurity interaction. The simulations show that when γm is smaller than γA1 and when |umin| is close to |uA1| (with the relative difference smaller than 20%), grain boundary grooving is prevented. This effect is explained by a decrease in the ratio of grain boundary diffusion to surface diffusion. Diffusion coefficients obtained by these simulations show that impurities at the grain boundaries which satisfy the above conditions (e. g., copper) strengthen surface diffusion without strengthening grain boundary diffusion.
Transactions of the Japan Society of Mechanical Engineers. A | 1994
Tomio Iwasaki; Naoya Sasaki; Norimasa Chiba; Yasuo Abe
We investigate the shear deformation of bicrystalline aluminum using a molecular dynamics simulation. The computational cell contains a [001](310)Σ=5 tilt grain boundary. In simulations, we use a Morse potential. The simulations show that when the strain rate is small, and when the temperature is high, the strain rate is proportional to the shear force and the Boltzmann factor. The activation energy for the deformation agrees well with the activation energy for grain-boundary sliding and migration induced by thermal activation. This means that diffusions of the same type occur in both cases. However, this type of diffusion does not seem to occur when the temperature is low. When the strain rate is sufficiently large, yielding is observed in the grain. The critical shear force becomes smaller as the temperature is raised.
Transactions of the Japan Society of Mechanical Engineers. A | 1995
Tomio Iwasaki; Naoya Sasaki; Norimasa Chiba; Yasuo Abe
Transactions of the Japan Society of Mechanical Engineers. A | 1994
Tomio Iwasaki; Naoya Sasaki; Norimasa Chiba; Yasuo Abe
JSME international journal. Series A, mechanics and material engineering | 1993
Naoya Sasaki; Tomio Iwasaki; Norimasa Chiba; Yasuo Abe; Yuichi Ishikawa
Transactions of the Japan Society of Mechanical Engineers. A | 1994
Naoya Sasaki; Tomio Iwasaki; Norimasa Chiba; Yasuo Abe
Transactions of the Japan Society of Mechanical Engineers. A | 1993
Tomio Iwasaki; Naoya Sasaki; Norimasa Chiba; Yasuo Abe
Transactions of the Japan Society of Mechanical Engineers. A | 1992
Tomio Iwasaki; Naoya Sasaki; Norimasa Chiba; Yasuo Abe
Transactions of the Japan Society of Mechanical Engineers. A | 1991
Naoya Sasaki; Tomio Iwasaki; Norimasa Chiba; Yasuo Abe; Yuichi Ishikawa
Japanese journal of tribology | 1998
Youichi Kawakubo; Naoya Sasaki; Mieko Ishii