Yoshiyuki Shoji

Development of low-activation al alloys for D-T burning fusion device II. Fabrication and characterization of a large plate

Abstract The first industrial fabrication of a large plate of low-activation Al-4% Mg-1% Li alloy as a candidate material for a fusion device, with a size of 25 mm × 1000 mm × 2000 mm, and characterization of its chemical composition, mechanical properties, electrical resistivity, and weldability are reported. Although the final yield of material, starting from the initial melting of Al and solute elements, is low, namely 135 3000 , the plate had sound structural material properties as expected from previous laboratory experiments.

Vaporization study on lanthanum–cerium alloys by mass-spectrometric method

Abstract The partial vapor pressures of La(g) and Ce(g) over La x Ce 1− x alloys ( x =0.00, 0.05, 0.29, 0.50, 0.80, 1.00) were measured with a time-of-flight mass-spectrometer equipped with a tungsten Knudsen cell over the temperature range of 1592–1781 K. The thermodynamic activities of lanthanum and cerium in the liquid alloys were determined by comparing the partial vapor pressures of La(g) and Ce(g) over the alloys with those over the pure metals, respectively. The thermodynamic activities were also calculated from the ion intensity ratios of two components (lanthanum and cerium) in the alloys using the equation derived by Belton and Fruehan. Both activities for each element, thus obtained, were in good agreement with each other and almost obeyed Raoults law. The partial molar Gibbs free energy, and the Gibbs free energy of formation were calculated from the thermodynamic activity values.

Vapor pressure measurements of LaGd alloys

Abstract The vapor pressures of La(g) and Gd(g) over La x Gd 1− x alloys ( x = 0.00, 0.12, 0.22, 0.45, 0.70, 0.74, 0.85, 1.00) were measured with a time-of-flight mass spectrometer equipped with a tungsten Knudsen cell over the temperature range 1588 to 1797 K. The chemical activities of lanthanum and gadolinium in the alloys were determined by comparing the vapor pressures of La(g) and Gd(g) over the alloys with those over the pure metals. The chemical activities, thus obtained, showed positive deviations from Raoults law over the entire compositional range. The interatomic force between gadolinium and lanthanum was thought to be repulsive. The partial molar Gibbs free energy and the Gibbs free energy, enthalpy and entropy of formation were calculated from the activity values.

Vapor Pressure Measurements of Lanthanum–Bismuth Alloys by Mass-Spectrometric Method1

Vapor pressures of Bi2 (g) over La0.03 Bi0.97 and two-phase mixtures of Bi+LaBi2, LaBi2+LaBi, LaBi+La4Bi3, La4Bi3+La5Bi3, and La5Bi3+La2 Bi were measured in the temperature range from 795 to 1066μK with a time-of-flight mass spectrometer equipped with a tungsten Knudsen cell. The vapor pressure of Bi2(g) over the two-phase mixtures of La2Bi+La could not be detected experimentally in this temperature range. The thermodynamic activity of bismuth was determined from the vapor pressure of Bi2(g). Thermodynamic activities of lanthanum over alloys were derived from those of bismuth in the alloys in this study and that of lanthanum in the bismuth in a previous study by graphic integration of the Gibbs–Duhem equation. Thermodynamic quantities such as Gibbs free energy of formation, excess enthalpy, etc., were also calculated from the thermodynamic activities.

Vaporization study on lanthanum–uranium and cerium–uranium alloys by mass-spectrometric method

Abstract The partial vapor pressures of La(g) and U(g) over La x U 1− x alloys ( x =0.01, 0.02, 0.05, 0.20, 0.99) and Ce(g) and U(g) over Ce x U 1− x alloys ( x =0.01, 0.02, 0.04, 0.10, 0.20, 0.97, 0.99) were measured with a time-of-flight mass-spectrometer equipped with a tungsten Knudsen cell over the temperature range between 1619 and 1886 K. The thermodynamic activities of lanthanum or cerium and uranium in the liquid alloys were calculated from the ion intensity ratios of two components (lanthanum or cerium and uranium) in the alloys using the equation derived by Belton and Fruehan. These systems were found to exist as the two phases in the wide compositional range and to exhibit positive deviations from ideal behavior. The Gibbs free energy of formation was calculated from the thermodynamic activity values.

Vaporization study on lanthanum–neodymium alloys by mass-spectrometry

Abstract Partial vapor pressure of Nd(g) over La x Nd 1− x alloys ( x =0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80 and 0.90) was measured with a time-of-flight mass-spectrometer equipped with a tungsten Knudsen cell over the temperature range of 1474–1767 K. Thermodynamic activity of neodymium in the liquid alloys was determined by comparing the partial vapor pressure of Nd(g) over the alloys with that over the pure metal. The thermodynamic activity of lanthanum in the alloys was calculated from that of neodymium obtained experimentally in this study by graphic integration using the Gibbs–Duhem equation. Both activities for each element, thus obtained, showed positive deviations from Raoults law over the entire compositional range. Thermodynamic quantities such as Gibbs free energy of formation, excess enthalpy etc. were also calculated from the thermodynamic activities.