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先進ブランケットの液体燃料増殖材や液体ダイバータの冷却材として液体金属及び溶融塩が期待されてい る．これらの高温融体中における候補構造材料及び機能性材料との共存性について解説する．

The corrosion of reduced activation ferritic martensitic steel, JLF-1 (Fe–9Cr–2W–0.1C), in high-purity Li was quite small. However, carbon in the steel matrix was depleted by the immersion to the Li. The depletion caused the phase transformation of the steel surface in which the morphology of the steel surface changed to ferrite structure from initial martensite structure. The phase transformation degraded the mechanical property of the steel. However, the carbon depletion and the phase transformation of the steel were suppressed in carbon doped Li. The carbon in the steel was chemically stable and did not dissolve into the Li when the carbon potential in the Li was high. The concentration of nitrogen and oxygen must be kept as low as possible because the corrosion was larger when the concentration of oxygen or nitrogen in the Li was higher. The chemical reaction between the steel and the Li compounds of Li3N and Li2O was also investigated. The corrosion of the JLF-1 steel in Pb–17Li was summarized as the dissolution of Fe and Cr from the steel into the melt. The corrosion of the specimen with Er2O3 coating fabricated by metal organic decomposition process in the Li and the Pb–17Li was investigated. The coating was deformed, cracked and partially exfoliated in the liquid metals, though the oxide itself was chemically stable in the liquid breeders. The damage was probably made by the stress, which was generated by a large difference of the thermal expansion ratio between the solidified Li or Pb–17Li and the coating during a heat up and a cool down process of the corrosion test.

Thermophysical properties of four rare earth elements, namely Lanthanum (La), Praseodymium (Pr), Neodymium (Nd), and Terbium (Tb) have been measured using electrostatic levitation techniques. The understanding of the nature and behavior of rare earth metals in their liquid phases requires accurate values of their physical properties. However, keeping samples in their liquid phases free from contamination long enough to carry out measurements represents a formidable challenge. This is due to high reactivity and melts contamination of these elements with crucibles or gaseous environment. The use of an electrostatic levitator in vacuum conditions circumvents these difficulties and permits the measurements of the density, the surface tension, and the viscosity of these metals above and below their melting temperature. In this paper, the measurement methods as well as the levitation apparatus are introduced and measured values are reported., 資料番号: AA0063800000, レポート番号: JAXA-RR-07-014E

シアーセル法は、融液の拡散係数を高精度に測定するための新たな測定法のひとつである。シアーセル法を用いた場合の測定誤差は、主に液体試料を接合するときの流動により生じることが明らかにされている。試料温度1,600KにおいてAg-Auの拡散係数について拡散時間を変えながら測定し、測定誤差を定量的に評価した。, Shear cell method is one of the advanced experimental techniques to measure diffusion coefficients in liquids. In order to measure diffusion coefficient more accurately, we studied error factors of this method. The shear convection due to the shear cell method is one of the major error factors of the measurement of diffusion coefficient. To clarify effects of shear convection, we carried out the diffusion coefficient measurement of Au in liquid Ag at temperature of 1,600 K with the variation of diffusion time. We obtained the time dependence of Au diffusion coefficient measured and clarify the experimental error derived from shear convection., 資料番号: AA0063323002, レポート番号: JAXA-RR-06-015E

シアーセル法は、融液の拡散係数を測定するためのもっとも優れた方法の1つである。我々は、シアーセル法を用いてより高精度な融液の拡散係数を獲得するため、本方法に潜在する誤差要因の特定とその対策を検討した。特に拡散係数の測定値に対する拡散対接合時の対流(シアー対流)の影響を明らかにするため、実験温度1,300Kおよび1,500Kにおいて拡散時間をパラメータにとりモデル試料としてAuAg合金を採用して拡散実験を行った。溶融Ag中のAuの拡散係数の拡散保持時間依存性から拡散保持時間を3時間以上とすることでシアー対流の影響を排除することが可能であることが判明した。, Shear cell method is one of the advanced experimental techniques to measure diffusion coefficients in liquids. In order to measure diffusion coefficient more accurately, we studied error factors of this method. The shear convection due to the shear cell method is one of the major error factors of the measurement of diffusion coefficient. To clarify effects of shear convection, we carried out the diffusion coefficient measurement of Au in liquid Ag at the temperatures of 1,300 K and 1,500 K with the variation of diffusion time. We obtained the diffusion time dependence of Au diffusion coefficient in liquid Ag. The errors due to the shear convection can be eliminated by adopting the diffusion time over three hours., 資料番号: AA0049301001, レポート番号: JAXA-RR-05-034E

X線・中性子散乱法と静電浮遊炉を組み合わせることにより、超高温や過冷却液体の構造を精密に測定することが可能である。本研究は、シリコンやジルコニウムなど高温金属液体の液体構造を測定するために、構造解析用の静電浮遊炉を新たに開発し、高輝度放射光および中性子線を用いた散乱実験を試みた。実験の結果、これらの液体の静的構造因子(過冷却液体状態を含む)を高精度に測定することができた。, The structure of undercooling liquid state is one of the important subjects of materials science. The levitation techniques are powerful tools for the investigation of undercooled liquids. In this research, we developed the electrostatic levitation furnace for the liquid structure analysis due to the neutron and x-ray diffraction methods. The apparatus was tested by using a synchrotron radiation facility, a laboratory X-ray source and a reactor. The structures of several kinds of materials were investigated and the liquid structures can be measured with high precision., 資料番号: AA0049301004, レポート番号: JAXA-RR-05-034E

The microgravity condition is one of the ideal conditions for the measurements of diffusion coefficients in high temperature melts because of the absence of convection in the liquid sample. The many kinds of experimental techniques, such as, the long capillary method and the shear cell method, have been devised in the ground base research for the measurement of diffusion coefficient in such high temperature melts. Recently, the shear cell technique coupled with the microgravity condition was applied to the measurements of high temperature metallic melts. This technique enables us to measure the diffusion coefficient with high precision. In this paper, a brief discussion is given for the trends of previous diffusion experiments in space performed by Japanese researchers. Recently, Japanese space agency, JAXA, is developing the shear cell technique for the future space experiments in JEM. The current status of the development of our shear cell technique is summarized and new results are presented for typical experiments on the ground by using test samples, for example, liquid silver-gold alloys., 資料番号: AA0049301002, レポート番号: JAXA-RR-05-034E

The shear cell method for the diffusion experiment on the ground is being studied to establish the reliable experimental process of diffusion in liquids even on the ground and to present the reference data for experiment under microgravity. The adopted systems are liquid Ge-Sn and Ge-Si systems. It is not always easy to measure diffusion coefficients in these systems, because those solid-liquid coexisting regions are wide. The wide solid-liquid coexisting region causes the segregation problems on the sample preparation, and the analysis of concentration profile. The methods for obtaining homogeneous pieces of diffusion couple sample were investigated and a concentration profile after the diffusion experiment was analyzed accurately. Shear cell experiments of Ge-Sn system were performed in the temperature range, 750 - 1,300 K, as a prototype experiment. Moreover, the method of the concentration analysis of the Ge-Si sample was studied., 資料番号: AA0048709007, レポート番号: JAXA-RR-04-044E

資料番号: AA0048709008, レポート番号: JAXA-RR-04-044E

Shear cell method is one of the most advanced experimental techniques to measure diffusion coefficients in liquids. In order to measure the diffusion coefficient more accurately, error factors of this method were studied. The shearing convection in the shear cell method is one of the major error factors of the measurement of diffusion coefficient. To clarify the effect of shearing convection on diffusion coefficient, the measurement of diffusion coefficient of Au in Ag melt was carried out at temperatures of 1,300 K and 1,500 K with the variation of diffusion time. The time dependence of Au diffusion coefficient in Ag melt was obtained and the feature of experimental error arising from the shearing convection was clarified., 資料番号: AA0048709006, レポート番号: JAXA-RR-04-044E

資料番号: AA0048709001, レポート番号: JAXA-RR-04-044E

The containerless technique is one of the latest methods for the handling of matters at high temperature and in undercooled liquid states. In this research project, the electrostatic levitation technique has been applied to the structural analysis of liquids by using the neutron and X-ray scattering techniques. The current status of this subject is described briefly., 資料番号: AA0048709004, レポート番号: JAXA-RR-04-044E

In order to obtain the optimum way for the shear cell diffusion experiments, the investigation was performed for the factors minimizing the effect of the induced flow on joining a diffusion couple, such as the roughness of the shear cell disks, the shear velocity and the diffusion time. It was found that diffusion experiments should be performed using disks with rough surface at smaller shear velocity and that there is an optimum diffusion time for the diffusion experiments on the ground., 資料番号: AA0045399011, レポート番号: NASDA-TMR-020025E

Dynamic structures of liquid germanium at the temperature of 1,253 K were investigated by a first-principles molecular-dynamics simulation. To investigate long-range correlation functions the MD simulation was carried out not only with a cubic cell but also with a rectangular parallelepiped cell. The calculated dynamic structure factors and the dispersion relation are in excellent agreement with the results of a recent inelastic X-ray scattering experiment., 資料番号: AA0045399006, レポート番号: NASDA-TMR-020025E

Density measurement by the high-energy gamma ray attenuation method was briefly summarized. The results obtained for molten Ge and Sn up to 1,200 C were presented in comparing with those measured with other techniques., 資料番号: AA0045399010, レポート番号: NASDA-TMR-020025E

The dynamical structure factors of the liquid Ge are calculated theoretically and compared with the recent experimental results obtained by the inelastic x-ray scattering. The calculation is carried out by the simple purely theoretical method, i.e. by the viscoelastic theory, which is based on the effective pair potential obtained by the pseudopotential perturbation theory and the static structure factor calculated by the integral-equation theory in the modified hypernetted-chain (MHNC) approximation. It is shown that the calculated dynamical structure factors are in qualitative agreement with the experimental results and that the calculated dispersion relation agrees well with the experimental one., 資料番号: AA0045399001, レポート番号: NASDA-TMR-020025E

The structure factors, S(Q), of liquid tin was obtained by neutron diffraction last year. Analysis of this S(Q) was performed in comparison with the use of hard sphere model. The radial distribution function g(r) was calculated from the S(Q), then the first coordination numbers were estimated by the standard regime., 資料番号: AA0045399002, レポート番号: NASDA-TMR-020025E

To establish the shear cell technique for the diffusion coefficient measurement of high vapor pressure sample, the seal effect of B2O3 melts was investigated by using a simplified shear cell unit. Moreover, the seal effect was investigated by using a short form shear cell. Even for liquid samples with high vapor pressures, the seal effect of B2O3 can be expected., 資料番号: AA0045399013, レポート番号: NASDA-TMR-020025E

The first and clear experimental evidence for the transition from the steady to the oscillatory flow was presented by the non-contact temperature measurement of a molten tin surface and the surface flow visualization. The experimental study on thermocapillary convection of low Prandtl number fluid was carried out to understand transition behavior to oscillatory flow. The half-zone liquid bridge of molten tin was formed between hot and cold disks in high vacuum chamber (10(exp -5) Pa). The three radiation thermometers were used to measure the free surface temperature at a different azimuthal location at the same time. In addition, the temperature distribution at interface between liquid bridge and cold disk was measured by using very fine thermocouples to detect the transition point and to make clear the oscillation mode more precisely. It can be detected that the steady thermocapillary convection changes to oscillatory under certain condition. The effect of aspect ratio (L/r) on critical Marangoni number is investigated. The critical Marangoni number decreases with increasing the aspect number. This behavior agrees with numerical simulation done by Imaishi et al. qualitatively except for region of smaller aspect ration. The transducer with 3 x 3 LN element was made and checked its sensitivity. The sensor was verified the stability after heat treatment up to 500 C, which was same as actual thermocapillary experiment. The frequency band of oscillator was selected to get the clear echo signal. The optimal frequency was 6 to 14 MHz wide-band. The sphericity and surface roughness of Fe-Ni/SB were improved by an appropriate heat treatment technique on Ni plating process and by the organic additives to the Fe plating solution. The Fe plating rate was obtained. It was found that the thickness increased with time linearly. It could be verified that Fe and Ni plated Shirasu-balloons (Fe-Ni/SB) even in phi-0.1 mm reflected the ultrasonic., 資料番号: AA0045403006, レポート番号: NASDA-TMR-020026E

The technological development of shear flow visualization is reported to clarify the effect of shear flow on the diffusion experiments. The experimental equipment was developed to visualize the flow pattern and the penetration depth of flow. A pair of test cells, which can slide each other, was used for the simulation of shear cell. The flow pattern was investigated by both a tracer tacking method and a photochromic method. The flow patterns during the shear motion were visualized clearly. It was found that the mass exchanges between the each cells occurs after the shear motion was stopped. The penetration length increased with Reynolds number. When Reynolds number was less than 2, the interflow depth becomes lower than 10 percent of the diameter., 資料番号: AA0045399012, レポート番号: NASDA-TMR-020025E

Outline of the database in the diffusion project is described. It includes the all documents of the conference and the meeting of diffusion project, experimental database, simulation database, physical properties and paper database. More than 500 papers are electronically stored. At present these are only open to members of diffusion project. This database should be open to public in future., 資料番号: AA0045399016, レポート番号: NASDA-TMR-020025E

As a continuation of the studies performed in the previous fiscal year, the study of feasibility of conducting the dynamic surface deformation measurement on the liquid bridge with various of diameter, to be utilized for the Liquid Bridge Marangoni Convection Experiments using the JEM Fluid Physics Experiment Facility (FPEF), was performed. From these studies, compatibility with the FPEF and the items to be developed were shown. One of them is the method to seal the sample or tracers for the small diameter liquid bridge formation equipment. Some of the methods to seal the sample and tracers have been proposed. Test plan using the Bread Board Model (BBM) of small diameter (5 mm) liquid bridge formation equipment was established to study them. BBM was designed and constructed based on the test plan, and then BBM tests were performed. Test results showed the feasibility of small diameter liquid bridge formation equipment for Marangoni Convection Experiments., 資料番号: AA0045403007, レポート番号: NASDA-TMR-020026E

The temperature dependence of the structure of liquid tin was studied from 773 to 1,873 K by a first-principles molecular-dynamics simulation. The calculated results were discussed with the neutron scattering experiments., 資料番号: AA0045399005, レポート番号: NASDA-TMR-020025E

For the purpose to evaluate atomic diffusive dynamics in liquid Sn the inelastic neutron scattering measurement has been carried out. The quasielastic neutron scattering in a part of the inelastic scattering results from the diffusion or structure relaxational motion. The obtained width of the quasielastic line versus momentum transfer Q deviates from Fick's law and close to the jump-diffusion model corresponding to water. As Sn is the almost coherent scatterer, this width is considered to be derived from the existence of the correlated motion of particles. The quasielastic line behavior in liquid Sn may represent the slow structural relaxation of the particle shell around the new site after the jump motion of a Sn atom in diffusion process., 資料番号: AA0045399008, レポート番号: NASDA-TMR-020025E

Several sets of numerical simulations were conducted to give realistic understandings of oscillatory Marangoni convection in half-zone liquid bridges of low Prandtl number fluid with various aspect ratios (from 0.6 to 2.2). Special emphasis was placed on the effects of the less-conductive supporting rods on the transition from axisymmetric steady flow to three dimensional steady and also to oscillatory three dimensional flow. The new simulation results revealed that the conductive heat transfer through the small gaps (1 mm in total) between the melt/rod interface and the temperature measuring points causes significant temperature drop which provide with serious error in estimating Marangoni numbers. This conductive temperature drop is the major reason of the discrepancy between the numerical results in preceding years and the experimental results obtained in NASDA. The effect of the finite conductivity of the rods causes additional effect through the non-uniform temperature distributions on the melt/rod interface. This effect is not negligible but yet minor., 資料番号: AA0045403005, レポート番号: NASDA-TMR-020026E

The atomic dynamics of liquid Ge, Sn and Na are studied based on the mode coupling theory. The memory functions for the velocity autocorrelation functions (VAF) are obtained for liquid Ge, Sn and Na numerically from the VAF obtained by the molecular-dynamics simulations and are divided into the binary-collision term and the mode-coupling term. For the liquid Na the memory functions are also calculated theoretically by the mode-coupling theory and compared with that obtained numerically. The characteristic features of the memory functions for the liquid Ge and Sn near the triple point are qualitatively different from those for the typical liquids and are similar to those of the memory function of the liquid Na at high temperatures, which cannot be described by the mode-coupling theory., 資料番号: AA0033133003, レポート番号: NASDA-TMR-010019E

The volume of liquid metals (liquid states of group IA(1), IIA(2), IIB(12), IIIB(13) and IVB(14) elements) was theoretically calculated based on a hard sphere model in the uniform background potential. The theoretically obtained atomic volume is in good agreement with experimental volume for all liquids studied here even for liquid group IVB(14) elements., 資料番号: AA0033133004, レポート番号: NASDA-TMR-010019E

以下の主題を論じた。液体金属の剛体球模型、液体の精密化理論、液体リチウムの分子動力学シミュレーション、剛体球流体の自己拡散、液体リチウムの同位体効果、高反応性液体金属の微小重力拡散、Ag-Cu合金の拡散、液体すずの構造、液体すずとゲルマニウムの有効対ポテンシャル、拡散測定用せん断セル法、液体シリコンの濡れ性と反応、拡散実験に及ぼす凝固効果、および拡散試料中の対流の解析。, The following topics were discussed: hard sphere model of liquid metal, refined theory of liquid, molecular dynamics simulation of liquid lithium, self-diffusion of hard sphere fluids, isotope effect of liquid lithium, microgravity diffusion of highly reactive liquid metals, diffusion of Ag-Cu alloys, structure of liquid tin, effective pair potential of liquid tin and germanium, shear cell method for diffusion measurement, wettability and reaction of liquid silicon, solidification effects on diffusion experiments, and analysis of convection in diffusion sample., 資料番号: AA0029039000, レポート番号: NASDA-TMR-000013E

液体内の物質移動の機構を明らかにするため単純液体金属の分子動力学シミュレーションを行った。分子動力学シミュレーションでは、剛体球流体の自己拡散に対するSpeedyの式の有効性を検討した。剛体球流体の数値模型として無次元形の方程式を記述した。充填率、拡散係数、Enskogの式およびSpeedyの式を定義し、拡散係数とEnskogの式に基づき後方散乱係数を計算した。剛球体系は充填率に依存して液体または固体としての性質を示す。液体と固体間の遷移状態は充填率だけではなく初期条件にも左右されることが分かった。Boublik-Nozbeda方程式に基づいて遷移状態を論じ、また、本分子動力学シミュレーションの有効性を明らかにした。剛球体系の液体構造を動径分布関数の形で評価した。本剛球体系の構造は液状であるように見られ、液相に特有の振動が存在する。無次元拡散係数と後方散乱係数の充填率への依存度を計算した。拡散係数は充填率が0.05〜0.45の範囲でSpeedyの式と一致した。, The molecular dynamics simulation of simple liquid metals was carried out in order to clarify the mechanism of mass transfer in liquids. In the molecular dynamics simulation, the validity of Speedy et al's formula for self-diffusion of hard sphere fluids was studied. Equations in non-dimensional forms were written for numerical modeling of hard sphere fluid. Packing fraction, diffusion coefficient, Enskog's formula and Speedy's formula were defined respectively. The back scattering factor was calculated based on the diffusion coefficient and Enskog's formula. The hard sphere system behaves as a liquid or a solid depending on the packing fraction. Transition state between liquid and solid is found not to depend on only the packing fraction but also on the initial conditions. The transition state was discussed based on Boublik-Nozbeda equation, and the validity of the present molecular dynamic simulation was shown. The liquid structure of the hard sphere system was evaluated in the form of radial distribution function. The structure of present hard sphere system seems to be liquid like and there exists a specific oscillation in liquid phase. The dependence of the non-dimensional diffusion coefficient and the back scattering factor on packing fraction was calculated. The diffusion coefficient agreed with the Speedy's formula over the packing fraction range 0.05 to 0.45., 資料番号: AA0029039004, レポート番号: NASDA-TMR-000013E

液体金属の構造を分子動力学(MD)シミュレーションを使って研究するには、原子間の相互作用の情報が必要となる。ゲルマニウムやすずなどの液体金属では、液状でも共有結合が残存しているため、有効対ポテンシャルの計算に、殆ど自由な電子(NFE)モデルを使用できない。この場合に、実験静的構造因子から有効対ポテンシャルを導く逆解法が有効な方法となる。本論文では、融点近傍の実験構造データから液体すずと液体ゲルマニウムの有効対ポテンシャルを導き、その計算にMDシミュレーションを行った。MDシミュレーションは液体すずでは523K、液体ゲルマニウムでは1,253Kで行った。, The information of the interaction between atoms is necessary for the investigation of liquid metal structure, using the Molecular-Dynamics (MD) simulation. For the liquid germanium or liquid tin metals, Nearly-Free-Electron (NFE) model can not be used for calculating the effective pair potential, since covalent bonds may remain even in the liquid states. In this case, the inverse method, in which the effective pair potential is derived from the experimental static structure factor, is the most effective method. In this paper, the effective pair potential of liquid tin and liquid germanium are derived from experimental structure data near the melting points and MD simulation is carried out for its calculation at 523 K and 1,253 K for tin and germanium, respectively., 資料番号: AA0029039013, レポート番号: NASDA-TMR-000013E

Thermophysical properties of liquid metals, such as the density, the viscosity and the compressibility, are necessary for the modeling of diffusion phenomena in liquid germanium alloys. These properties were investigated by several kinds of experimental method and have been accumulated as the database of thermophysical properties., 資料番号: AA0048709005, レポート番号: JAXA-RR-04-044E

Static structure of liquid germanium and alloys was measured by using the neutron scattering technique. The latest data of liquid structures measured by the research project are shown in this section., 資料番号: AA0048709003, レポート番号: JAXA-RR-04-044E

学位授与大学：京都大学 ; 取得学位：博士(工学) ; 学位授与年月日：2008-01-23 ; 学位の種類：新制・論文博士 ; 学位記番号：論工博第3981号 ; 報告番号：乙第12157号 ; 整理番号：25703 ; 請求記号：新制/工/1424