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Akihisa Inoue - One of the best experts on this subject based on the ideXlab platform.
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viscosity measurements of zr55cu30al10ni5 and zr50cu40 xal10pdx x 0 3 and 7 at supercooled liquid alloys by using a penetration viscometer
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007Co-Authors: S Maeda, T Yamasaki, Yoshihiko Yokoyama, Daisuke Okai, Takeshi Fukami, Hisamichi Kimura, Akihisa InoueAbstract:Abstract Viscosity of Zr 55 Cu 30 Al 10 Ni 5 and Zr 50 Cu 40− x Al 10 Pd x ( x = 0, 3 and 7 at.%) supercooled liquid alloys having bulk metallic glass forming ability has been measured by using a penetration viscometer with a Cylindrical Probe under high speed heating conditions at heating rates between 20 and 400 K/min in the temperature range from the glass transition temperatures ( T g ) up to above the crystallization temperatures. Effect of Pd addition on the viscosity of Zr-base supercooled liquid alloys has been also examined. The viscosity of these alloys decreased with increasing the heating rate and tended to saturate at the heating rate of 200 K/min and above. These viscosities can be well represented by the Arrhenius relation. The activation energy for viscous flow for Zr 55 Cu 30 Al 10 Ni 5 supercooled liquid alloys was about 350 kJ/mol. In the Zr 50 Cu 40− x Al 10 Pd x ( x = 0, 3 and 7 at.%) alloys, the viscosities increased with increasing the Pd-content, while the activation energy for viscous flow decreased from 337 to 276 kJ/mol.
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viscosity measurements of zr55cu30al10ni5 supercooled liquid alloys by using penetration viscometer under high speed heating conditions
Intermetallics, 2006Co-Authors: T Yamasaki, S Maeda, Yoshihiko Yokoyama, Daisuke Okai, Takeshi Fukami, Hisamichi Kimura, Akihisa InoueAbstract:Abstract The viscosity of Zr55Cu30Al10Ni5 supercooled liquid alloys having bulk metallic glass forming ability was measured using a penetration viscometer with a Cylindrical Probe under at heating rates as high as 400 °C/min. Viscosity decreased with an increase in the heating rate and tended to saturate at 200 °C/min and above. This may partly indicate a decrease in the oxygen contamination from the measuring atmosphere and partly due to differences in structural relaxation during heating at various rates. The viscosity of these alloys can be well represented by an Arrhenius relation. The activation energies for viscous flow with various heating rates were all at values of about 340–350 kJ/mol. Viscosity follows a Vogel–Fulcher–Tammann (VFT) relationship over the entire temperature range.
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viscosity measurements of zr55cu30al10ni5 and pd40cu30ni10p20 supercooled liquid alloys by using a penetration viscometer
Materials Transactions, 2005Co-Authors: T Yamasaki, S Maeda, Yoshihiko Yokoyama, Daisuke Okai, Takeshi Fukami, Hisamichi Kimura, Akihisa InoueAbstract:Viscosity of Zr 55 Cu 30 Al 10 Ni 5 and Pd 40 Cu 30 Ni 10 P 20 supercooled liquid alloys having bulk metallic glass forming ability has been measured by using a penetration viscometer with a Cylindrical Probe under high speed heating conditions at heating rates between 20 and 400°C/ min in the temperature range from the glass transition temperatures (Tg) up to above the crystallization temperatures. The viscosity of these alloys decreased with increasing the heating rate and tended to saturate at the heating rate of 200°C/min and above. Their viscosity could be well represented by the Arrhenius relation. The activation energies for viscous flow for Zr 55 Cu 30 Al 10 Ni 5 and Pd 40 Cu 30 Ni 10 P 20 supercooled liquid alloys were about 350 and 250kJ/mol, respectively. The viscosity was also fitted by a Vogel-Fulcher-Tammann (VFT) relationship over the entire temperature range.
J R Sanmartin - One of the best experts on this subject based on the ideXlab platform.
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Bare-tether cathodic contact through thermionic emission by low-W materials
2020Co-Authors: Xin Chen, J R SanmartinAbstract:In absence of a low-impedance plasma contactor, a bare tether emits current through ion collection along the cathodic segment. The current flowing along the tether vanishes at both ends and the tether is said to be completely passive and electrically floating. In this case, under OML electron/ion collection, the anodic-to-cathodic length ratio is low because the ions are much heavier than the electrons which reduces the length-averaged current. A low-work-function electron-emitting material C12A7 : e − was developed by H. Hosono's group at the University of Tokyo John D. Williams brought such advances in materials science to the tether community. In work together with J. R. Sanmartin and L. P. Rand, C12A7 : e − was proposed as coating for floating bare tethers With this low-W coating, each point on the cathodic segment of a kilometers-long floating bare-tether would emit current as if it were part of a hot Cylindrical Probe uniformly polarized at the local tether bias, under 2D Probe conditions that are also applied to the anodic-segment analysis. Around a negatively biased Probe with intense thermionic emission, immersed in plasma, a double layer (DL) would be established, with electrons being emitted from the tether and ions coming from the ambient plasma. As shown i
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low work function thermionic emission and orbital motion limited ion collection at bare tether cathodic contact
Physics of Plasmas, 2015Co-Authors: Xin Chen, J R SanmartinAbstract:With a thin coating of low-work-function material, thermionic emission in the cathodic segment of bare tethers might be much greater than orbital-motion-limited (OML) ion collection current. The space charge of the emitted electrons decreases the electric field that accelerates them outwards, and could even reverse it for high enough emission, producing a potential hollow. In this work, at the conditions of high bias and relatively low emission that make the potential monotonic, an asymptotic analysis is carried out, extending the OML ion-collection analysis to investigate the Probe response due to electrons emitted by the negatively biased Cylindrical Probe. At given emission, the space charge effect from emitted electrons increases with decreasing magnitude of negative Probe bias. Although emitted electrons present negligible space charge far away from the Probe, their effect cannot be neglected in the global analysis for the sheath structure and two thin layers in between sheath and the quasineutral region. The space-charge-limited condition is located. It is found that thermionic emission increases the range of Probe radius for OML validity and is greatly more effective than ion collection for cathodic contact of tethers.
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Cylindrical langmuir Probes beyond the orbital motion limited regime
Physics of Plasmas, 2000Co-Authors: R. D. Estes, J R SanmartinAbstract:The current I to a Cylindrical Probe at rest in an unmagnetized plasma, with Probe bias highly positive, is determined. The way I lags behind the orbital-motion-limited (OML) current, IOML∝R, as the radius R exceeds the maximum radius for the OML regime to hold, is of interest for space-tether applications. The ratio I/IOML is roughly a decreasing function of R/λDe−Rmax/λDe, which is independent of bias, with λDe the electron Debye length and Rmax/λDe roughly an increasing function of the temperature ratio, Ti/Te. The dependence of current on ion energy is used to discuss the effect of Probe motion through the plasma, a case applying to tethers in low orbit.
T Yamasaki - One of the best experts on this subject based on the ideXlab platform.
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viscosity measurements of zr55cu30al10ni5 and zr50cu40 xal10pdx x 0 3 and 7 at supercooled liquid alloys by using a penetration viscometer
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007Co-Authors: S Maeda, T Yamasaki, Yoshihiko Yokoyama, Daisuke Okai, Takeshi Fukami, Hisamichi Kimura, Akihisa InoueAbstract:Abstract Viscosity of Zr 55 Cu 30 Al 10 Ni 5 and Zr 50 Cu 40− x Al 10 Pd x ( x = 0, 3 and 7 at.%) supercooled liquid alloys having bulk metallic glass forming ability has been measured by using a penetration viscometer with a Cylindrical Probe under high speed heating conditions at heating rates between 20 and 400 K/min in the temperature range from the glass transition temperatures ( T g ) up to above the crystallization temperatures. Effect of Pd addition on the viscosity of Zr-base supercooled liquid alloys has been also examined. The viscosity of these alloys decreased with increasing the heating rate and tended to saturate at the heating rate of 200 K/min and above. These viscosities can be well represented by the Arrhenius relation. The activation energy for viscous flow for Zr 55 Cu 30 Al 10 Ni 5 supercooled liquid alloys was about 350 kJ/mol. In the Zr 50 Cu 40− x Al 10 Pd x ( x = 0, 3 and 7 at.%) alloys, the viscosities increased with increasing the Pd-content, while the activation energy for viscous flow decreased from 337 to 276 kJ/mol.
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viscosity measurements of zr55cu30al10ni5 supercooled liquid alloys by using penetration viscometer under high speed heating conditions
Intermetallics, 2006Co-Authors: T Yamasaki, S Maeda, Yoshihiko Yokoyama, Daisuke Okai, Takeshi Fukami, Hisamichi Kimura, Akihisa InoueAbstract:Abstract The viscosity of Zr55Cu30Al10Ni5 supercooled liquid alloys having bulk metallic glass forming ability was measured using a penetration viscometer with a Cylindrical Probe under at heating rates as high as 400 °C/min. Viscosity decreased with an increase in the heating rate and tended to saturate at 200 °C/min and above. This may partly indicate a decrease in the oxygen contamination from the measuring atmosphere and partly due to differences in structural relaxation during heating at various rates. The viscosity of these alloys can be well represented by an Arrhenius relation. The activation energies for viscous flow with various heating rates were all at values of about 340–350 kJ/mol. Viscosity follows a Vogel–Fulcher–Tammann (VFT) relationship over the entire temperature range.
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viscosity measurements of zr55cu30al10ni5 and pd40cu30ni10p20 supercooled liquid alloys by using a penetration viscometer
Materials Transactions, 2005Co-Authors: T Yamasaki, S Maeda, Yoshihiko Yokoyama, Daisuke Okai, Takeshi Fukami, Hisamichi Kimura, Akihisa InoueAbstract:Viscosity of Zr 55 Cu 30 Al 10 Ni 5 and Pd 40 Cu 30 Ni 10 P 20 supercooled liquid alloys having bulk metallic glass forming ability has been measured by using a penetration viscometer with a Cylindrical Probe under high speed heating conditions at heating rates between 20 and 400°C/ min in the temperature range from the glass transition temperatures (Tg) up to above the crystallization temperatures. The viscosity of these alloys decreased with increasing the heating rate and tended to saturate at the heating rate of 200°C/min and above. Their viscosity could be well represented by the Arrhenius relation. The activation energies for viscous flow for Zr 55 Cu 30 Al 10 Ni 5 and Pd 40 Cu 30 Ni 10 P 20 supercooled liquid alloys were about 350 and 250kJ/mol, respectively. The viscosity was also fitted by a Vogel-Fulcher-Tammann (VFT) relationship over the entire temperature range.
S Maeda - One of the best experts on this subject based on the ideXlab platform.
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viscosity measurements of zr55cu30al10ni5 and zr50cu40 xal10pdx x 0 3 and 7 at supercooled liquid alloys by using a penetration viscometer
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007Co-Authors: S Maeda, T Yamasaki, Yoshihiko Yokoyama, Daisuke Okai, Takeshi Fukami, Hisamichi Kimura, Akihisa InoueAbstract:Abstract Viscosity of Zr 55 Cu 30 Al 10 Ni 5 and Zr 50 Cu 40− x Al 10 Pd x ( x = 0, 3 and 7 at.%) supercooled liquid alloys having bulk metallic glass forming ability has been measured by using a penetration viscometer with a Cylindrical Probe under high speed heating conditions at heating rates between 20 and 400 K/min in the temperature range from the glass transition temperatures ( T g ) up to above the crystallization temperatures. Effect of Pd addition on the viscosity of Zr-base supercooled liquid alloys has been also examined. The viscosity of these alloys decreased with increasing the heating rate and tended to saturate at the heating rate of 200 K/min and above. These viscosities can be well represented by the Arrhenius relation. The activation energy for viscous flow for Zr 55 Cu 30 Al 10 Ni 5 supercooled liquid alloys was about 350 kJ/mol. In the Zr 50 Cu 40− x Al 10 Pd x ( x = 0, 3 and 7 at.%) alloys, the viscosities increased with increasing the Pd-content, while the activation energy for viscous flow decreased from 337 to 276 kJ/mol.
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viscosity measurements of zr55cu30al10ni5 supercooled liquid alloys by using penetration viscometer under high speed heating conditions
Intermetallics, 2006Co-Authors: T Yamasaki, S Maeda, Yoshihiko Yokoyama, Daisuke Okai, Takeshi Fukami, Hisamichi Kimura, Akihisa InoueAbstract:Abstract The viscosity of Zr55Cu30Al10Ni5 supercooled liquid alloys having bulk metallic glass forming ability was measured using a penetration viscometer with a Cylindrical Probe under at heating rates as high as 400 °C/min. Viscosity decreased with an increase in the heating rate and tended to saturate at 200 °C/min and above. This may partly indicate a decrease in the oxygen contamination from the measuring atmosphere and partly due to differences in structural relaxation during heating at various rates. The viscosity of these alloys can be well represented by an Arrhenius relation. The activation energies for viscous flow with various heating rates were all at values of about 340–350 kJ/mol. Viscosity follows a Vogel–Fulcher–Tammann (VFT) relationship over the entire temperature range.
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viscosity measurements of zr55cu30al10ni5 and pd40cu30ni10p20 supercooled liquid alloys by using a penetration viscometer
Materials Transactions, 2005Co-Authors: T Yamasaki, S Maeda, Yoshihiko Yokoyama, Daisuke Okai, Takeshi Fukami, Hisamichi Kimura, Akihisa InoueAbstract:Viscosity of Zr 55 Cu 30 Al 10 Ni 5 and Pd 40 Cu 30 Ni 10 P 20 supercooled liquid alloys having bulk metallic glass forming ability has been measured by using a penetration viscometer with a Cylindrical Probe under high speed heating conditions at heating rates between 20 and 400°C/ min in the temperature range from the glass transition temperatures (Tg) up to above the crystallization temperatures. The viscosity of these alloys decreased with increasing the heating rate and tended to saturate at the heating rate of 200°C/min and above. Their viscosity could be well represented by the Arrhenius relation. The activation energies for viscous flow for Zr 55 Cu 30 Al 10 Ni 5 and Pd 40 Cu 30 Ni 10 P 20 supercooled liquid alloys were about 350 and 250kJ/mol, respectively. The viscosity was also fitted by a Vogel-Fulcher-Tammann (VFT) relationship over the entire temperature range.
Daisuke Okai - One of the best experts on this subject based on the ideXlab platform.
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viscosity measurements of zr55cu30al10ni5 and zr50cu40 xal10pdx x 0 3 and 7 at supercooled liquid alloys by using a penetration viscometer
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007Co-Authors: S Maeda, T Yamasaki, Yoshihiko Yokoyama, Daisuke Okai, Takeshi Fukami, Hisamichi Kimura, Akihisa InoueAbstract:Abstract Viscosity of Zr 55 Cu 30 Al 10 Ni 5 and Zr 50 Cu 40− x Al 10 Pd x ( x = 0, 3 and 7 at.%) supercooled liquid alloys having bulk metallic glass forming ability has been measured by using a penetration viscometer with a Cylindrical Probe under high speed heating conditions at heating rates between 20 and 400 K/min in the temperature range from the glass transition temperatures ( T g ) up to above the crystallization temperatures. Effect of Pd addition on the viscosity of Zr-base supercooled liquid alloys has been also examined. The viscosity of these alloys decreased with increasing the heating rate and tended to saturate at the heating rate of 200 K/min and above. These viscosities can be well represented by the Arrhenius relation. The activation energy for viscous flow for Zr 55 Cu 30 Al 10 Ni 5 supercooled liquid alloys was about 350 kJ/mol. In the Zr 50 Cu 40− x Al 10 Pd x ( x = 0, 3 and 7 at.%) alloys, the viscosities increased with increasing the Pd-content, while the activation energy for viscous flow decreased from 337 to 276 kJ/mol.
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viscosity measurements of zr55cu30al10ni5 supercooled liquid alloys by using penetration viscometer under high speed heating conditions
Intermetallics, 2006Co-Authors: T Yamasaki, S Maeda, Yoshihiko Yokoyama, Daisuke Okai, Takeshi Fukami, Hisamichi Kimura, Akihisa InoueAbstract:Abstract The viscosity of Zr55Cu30Al10Ni5 supercooled liquid alloys having bulk metallic glass forming ability was measured using a penetration viscometer with a Cylindrical Probe under at heating rates as high as 400 °C/min. Viscosity decreased with an increase in the heating rate and tended to saturate at 200 °C/min and above. This may partly indicate a decrease in the oxygen contamination from the measuring atmosphere and partly due to differences in structural relaxation during heating at various rates. The viscosity of these alloys can be well represented by an Arrhenius relation. The activation energies for viscous flow with various heating rates were all at values of about 340–350 kJ/mol. Viscosity follows a Vogel–Fulcher–Tammann (VFT) relationship over the entire temperature range.
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viscosity measurements of zr55cu30al10ni5 and pd40cu30ni10p20 supercooled liquid alloys by using a penetration viscometer
Materials Transactions, 2005Co-Authors: T Yamasaki, S Maeda, Yoshihiko Yokoyama, Daisuke Okai, Takeshi Fukami, Hisamichi Kimura, Akihisa InoueAbstract:Viscosity of Zr 55 Cu 30 Al 10 Ni 5 and Pd 40 Cu 30 Ni 10 P 20 supercooled liquid alloys having bulk metallic glass forming ability has been measured by using a penetration viscometer with a Cylindrical Probe under high speed heating conditions at heating rates between 20 and 400°C/ min in the temperature range from the glass transition temperatures (Tg) up to above the crystallization temperatures. The viscosity of these alloys decreased with increasing the heating rate and tended to saturate at the heating rate of 200°C/min and above. Their viscosity could be well represented by the Arrhenius relation. The activation energies for viscous flow for Zr 55 Cu 30 Al 10 Ni 5 and Pd 40 Cu 30 Ni 10 P 20 supercooled liquid alloys were about 350 and 250kJ/mol, respectively. The viscosity was also fitted by a Vogel-Fulcher-Tammann (VFT) relationship over the entire temperature range.
