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Volume 67, Issue 12
Displaying 1-7 of 7 articles from this issue
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Gen Sasaki2003 Volume 67 Issue 12 Pages 689
Published: 2003
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSDownload PDF (138K) -
Yoshikazu Todaka, Minoru Umemoto, Yukinori Watanabe, Koichi Tsuchiya2003 Volume 67 Issue 12 Pages 690-696
Published: 2003
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThe surface nanocrystallization of various steels by air blast shot peening was investigated. It was found that nanocrystalline layers can be produced when higher shot speed and longer process period than those of conventional shot peening were applied. The produced nanocrystalline layers are several μm thick and show extremely high hardness. The layers have clear boundaries with the adjacent work-hardened regions. By annealing, slow grain growth without recrystallization is observed in the layers. Those characteristics are similar to those observed in the nanocrystalline layers produced by other techniques, such as ball milling, ball drop and particle impact deformations.View full abstractDownload PDF (1830K) -
Tomonori Watanabe2003 Volume 67 Issue 12 Pages 697-702
Published: 2003
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSIn order to understand how the macroscopic stress-strain properties of metallic materials are caused by their microscopic structures, we mathematically analyze a microscopic model which describes the dynamics of the materials by applying the theory of soliton system. We treat the typical atomic chain model which includes topological defects and consists of the thermal effect, the interactions of atoms, the friction from the environment and the external force. Moreover, we extend the chain model as a microscopic model by considering the effects of work hardening and internal friction. The dynamics of the microscopic model are given by the extended thermal overdamped sine-Gordon equation and a coupled equation. Solving the pair of equations by the perturbation expansion, we derive the macroscopic stress-strain response. In the static case, we show that inelastic behavior is displayed by the microscopic model and that it is derived from the effects of work hardening and internal friction. In the dynamic case, the shape of the hysteresis loop obtained by the microscopic model qualitatively corresponds to well-known experimental data better than that of the typical rheological model. We analytically show the effect of the work hardening and the interal friction on the hysteresis loop.View full abstractDownload PDF (345K) -
Gen Sasaki, Ryoichi Ono, Kazuhiro Matsugi, Osamu Yanagisawa, Lijun Yao2003 Volume 67 Issue 12 Pages 703-707
Published: 2003
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSTitanium (Ti) thin films were deposited on thermal oxidized silicon wafer by a spattering method. The influences of sputtering conditions on the microstructure of Ti films were investigated. The preferred orientation of Ti films change from (002) plane to (101) plane with an increase in sputtering temperature. The grain size and surface roughness increases with increasing spattering temperature till 653 K. On the other hand, the grain size and surface roughness of Ti film surface increases with increasing the thickness of films. This tendency was promoted at higher spattering temperature.View full abstractDownload PDF (976K) -
Zhenkai Xie, Teruyuki Ikeda, Yosiyuki Okuda, Hideo Nakajima2003 Volume 67 Issue 12 Pages 708-713
Published: 2003
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSLotus-type porous magnesium was fabricated by unidirectional solidification of melt dissolving hydrogen in a pressurized hydrogen atmosphere, which possesses many unidirectional cylindrical pores.
The sound absorption coefficient of porous magnesium whose sample face has many open pores was measured by standing-wave method in the range up to the frequency of sound of 4 kHz.
The absorption coefficient increases with decrease of the pore size, while it increases with increase of the porosity. Moreover, the peak value with high absorption coefficient is shifted toward higher frequency of sound when the thickness of the porous magnesium sample decreases.View full abstractDownload PDF (605K) -
Hideo Hoshiyama, Teruyuki Ikeda, Kenji Murakami, Hideo Nakajima2003 Volume 67 Issue 12 Pages 714-720
Published: 2003
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSPorous magnesium alloys, Mg-9Al-0.75Zn(AZ91D), Mg-3Al-1Zn(AZ31B), Mg-3Al-0.25Zn(AZ91D dilution with magnesium), were fabricated by unidirectional solidification under various pressures of hydrogen.
Optical micrographic observation of cross-sections of the porous magnesium alloys shows that cylindrical pores are aligned in the direction parallel to the solidification direction in the vicinity of bottom of the ingots, while spherical pores are evolved in the region apart from the bottom. The number of the cylindrical pores depends on the concentration of the alloying elements and the solidification velocity. The difference in pore morphology was discussed in the light of the equilibrium phase diagrams.View full abstractDownload PDF (2002K) -
2003 Volume 67 Issue 12 Pages e1
Published: 2003
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSPlease see Errata PDF Wrong:ç=ç0 exp (−Qv/kT), 1×10−3 s−1, η=η0 exp (−Qv/kT) Right:η=η0 exp (Qv/kT), 1×10−2 s−1, η=η0 exp (Qv/kT)View full abstractDownload PDF (180K)
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