高压物理学报

Thermal Radiation Field of Two Half-Space in Contact with Different Temperatures

ZHANG Guan-Ren

1995, 9(4): 241-246 . doi: 10.11858/gywlxb.1995.04.001

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Abstract:
By using the fluctuation dissipation theorem in electro-magnetic circuits, the thermal radiation energy density at any point of two half-space in contact with different temperatures derived. By approximate expansion of the derived equations, the temperature expressions at any point are obtained, which are exactly similar to that obtained by Grover and Urtiew except there appears an additional relaxation term which is also existent in the method of non-Fourier heat conduction. The result is in accord with that of the experimental and the relaxation time can be calculated by the properties of the material.

Constant Magnetic Permeability and Its Both Pressure and Frequency Characteristic in Nanometer－Scale Ultramicron of Pormalloy

SU Fang, XIE Bin, CHEN Yun-Hong

1995, 9(4): 247-256 . doi: 10.11858/gywlxb.1995.04.002

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Abstract:
By means of vacuum evaporation and condensation technique, nanometer-scale ultramicrons of Pormalloy (Fe-50wt%Ni, Fe-84wt%Ni) were prepared. It is found out with the method of TEM and X-ray diffraction that the composition of the ultramicron coincides with that of its mother alloy, and the average grain size is 16 nm (Fe-50Ni) and 19 nm (Fe-84Ni). Under room temperature and hydrostatic pressure of 36 various magnitudes ranging from 0.000 1 to 2.205 GPa the magnetization curve and initial magnetization curve were measured to reveal their relation with pressure. It is concluded: (1) The nanometer-scale ultramicron of both Pormalloy Fe-50wt%Ni and Fe-84wt%Ni possesses constant magnetic permeability; (2) Initial differential magnetic permeability, i varies with the pressure as follows: i=8.16+18.2p-24.7p2+18.1p3-6.55p4+0.908p5 (for Fe-50wt%Ni), i=5.38-0.169p+0.232p2-0.0786p3 (for Fe-84wt%Ni); (3) i of these ultramicrons decreases when f10 MHz, but i of alloy Fe-50Ni goes down when f1 MHz, i of alloy Fe-84Ni drops when f100 kHz, so applied frequency range of magnetic ultramicron core is one-two order of magnitude more than that of Pormalloy with the same composition.

A New Approximant of the Decagonal Quasicrystal and Ultrafine Particles Intercepted and Captured under High Static Pressure

YU Ri-Cheng, XU Da-Peng, SU Wen-Hui

1995, 9(4): 257-263 . doi: 10.11858/gywlxb.1995.04.003

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Abstract:
In this paper, we reported a new approximant of Al70Co15Ni10Tb5 decagonal quasi-crystal obtained by quenching from melting state (1 700 ℃) under high static pressure (7.0 GPa) for the first time. The approximant is a B-type orthorhombic crystalline phase and its lattice parameters are a=2.28 nm, b=1.6 nm, c=5.46 nm. A two-dimensional lattice model of the approximant is supposed by means of the high-resolution electron microscopy pattern. Besides, many ultrafine particles are found in this sample. They are spherical and their sizes are 30～40 nm.

Review of the Apparent Spectral Radiance from the Metal/Window Interface in the Measurement of Shock Temperature of Metals

TANG Wen-Hui, ZHANG Ruo-Qi, HU Jin-Biao, JING Fu-Qian

1995, 9(4): 264-269 . doi: 10.11858/gywlxb.1995.04.004

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Abstract:
It was shown that the temperature at the shocked ideal metal/window interface is a constant of time independent, so the apparent spectral radiance from the interface was alto regarded as time independent. This study indicates that the coefficient for light absorption of a metal decreases and the optical depth increases with shock compression. After in consideration of radiative transfer effective, the apparent spectral radiance from the ideal metal/window interface is actually time dependent, and the noticeable process with time keeps about ～10 ns since the arrival of the shock wave at this interface. This study also shows that the interface radiation of a metal in which the temperature distribution has a gradient could be treated as an equivalent radiation of an average temperature in the optical depth, a similar result as that derived from radiative transfer equation is obtained.

Many-Body Contributions for the Compressibility of Helium Atomic Cluster He9

LIU Fu-Sheng, GOU Qing-Quan, JING Fu-Qian

1995, 9(4): 270-274 . doi: 10.11858/gywlxb.1995.04.005

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Abstract:
Lowdin scheme was applied to calculate the repulsive potentials and their multi-body expansions of compressed atomic cluster He9. The micro-pressure and their expansions were calculated. The results show that many-body effects are important for the compressibility of atomic cluster He9. At the same volume, the pressure calculated by two-body approximation is 10%～30% higher than the actual many-body system. If three-body corrections are considered, the results become 1.5%～10% lower. When the four-body effect was included, the approximation calculations fit real system quite well. The compression properties of atomic cluster He9 are similar to the experimental results of solid helium.

Phase Transitions of Germanium during Pressure Quenching

ZHANG Fu-Xiang, WANG Wen-Kui

1995, 9(4): 275-278 . doi: 10.11858/gywlxb.1995.04.006

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Abstract:
The solidification parameters of germanium are directly measured under high pressure by a developed high pressure differential thermal analysis method. The differential thermal signal indicates that some phase transitions of Ge occurred during solidification under pressures of more than 3 GPa. High pressure phases of Ge Ⅲ and Ge Ⅳ are found in specimens by X-ray phase identification.

Studies on the Fracture Behaviour for 93 Tungsten Alloy

ZHANG Wan-Jia, YANG Zhong-Zheng

1995, 9(4): 279-288 . doi: 10.11858/gywlxb.1995.04.007

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Abstract:
Studies on the spallation behavior for 93 tungsten alloy have been performed with a compressed gas gun and a manganin piezoresistance gauge technique. It is found that tensile strain rate, alloy elements and metallurgical technology can significantly influence the fracture strength of this material. The metallographic and SEM examination of the recovered specimen show that 93 tungsten alloy spalls in a brittle way, the dominant fracture mode being cleavage of tungsten grains. Moreover, the interior damage degree of the tungsten alloy target is related to the tensile strain rate.

An Accrate Measurement Technique for Shock Hugoniot

WANG Jin-Gui

1995, 9(4): 289-295 . doi: 10.11858/gywlxb.1995.04.008

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Abstract:
In order to accurately measure the shock Hugoniot, we introduce the methods to reduce the relative errors in the measurements for the size of samples and the time intervals in the experiments and that to correct the errors caused by the inclined impact. The experimental results demonstrate that these methods are very valid and the measurement errors for the projectile and shock wave velocities are 0.2%～0.4% and ～0.1%, respectively. On the other hand, we introduce an optical fiber measurement technique to obtain both shock wave velocity and shock temperature in the experiments.

The Phase Transition of Fullerene Carbon under High Temperature and Pressure

ZHANG Hong-Huang, LIANG Ji, WEI Bing-Qing, GAO Zhi-Dong, ZHANG Ji-Hong, LIU Li-Fang, ZHAO Gang

1995, 9(4): 296-301 . doi: 10.11858/gywlxb.1995.04.009

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Abstract:
The phase transition of both C60 and Buckytube has been studied under high pressure up to 5～6 GPa and high temperature at 1 450 ℃ by cube equipment. The experimental results of SEM, X-ray and Uv/Vis show that most of the fullerene sample can transform to diamond with good crystal morphology, part transforms into graphite and a little has still been reserved. The transformed diamond crystal grows out of two-dimensional step and screwy step.

Measurement of Convective Diffusion Coefficients of CO2-Normal Octane and Normal Tetradecane System

WANG Li-Sheng, DONG Qing-Tian, LANG Zhao-Xin

1995, 9(4): 302-309 . doi: 10.11858/gywlxb.1995.04.010

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Abstract:
The method for measuring convective diffusion coefficients of driving gases in reservoir fluid by slim tube displacement method has been established in this work. The convective diffusion coefficients of CO2-normal octane and normal tetradecane systems have been measured and the effect of driving rate and the molecular weight of normal octane and normal tetradecane on the convective diffusion have been investigated.

1995 Vol. 9, No. 4

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