高压物理学报

Evolution Dynamic Equations of Dislocation Density

Dong Lian-Ke

1993, 7(4): 241-246 . doi: 10.11858/gywlxb.1993.04.001

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Abstract:
We regard the proliferation, the annihilating and the mutual reactions of the dislocations as chemical reactions, dislocations under action of heat activation will have properties of diffusion. Therefore a dislocation system is a reaction-diffusion system. Two equations of evolution dynamics for dislocation density are given based on the self-organization theory, in which the first equation will be transformed to the second equation when the structure imbalance of the system happened. The first equation contains the symmetry-breaking which will launch doublet according to Higgs mechanism.

Theoretical Studies of the Thermal Relaxation at the Materials Interface under Shock Compression

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

1993, 7(4): 247-253 . doi: 10.11858/gywlxb.1993.04.002

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Abstract:
The thermal relaxation processes at metal/window interfaces under shock compression are studied. Starting from the contact resistance model, a functional relation between the thermal relaxation time and the interface thermal reistance as well as the thermal transport coefficients of materials is obtained. The present model is compared with Grover and Urtiew's model. Two non-coincidence experimental results can be explained by the present model, and the reasons for the contact resistance are analyzed tentatively.

The Microstructure of Shock Wave-Processed 45 Steel

JIN Xiao-Gang, WANG Hong

1993, 7(4): 254-259 . doi: 10.11858/gywlxb.1993.04.003

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Abstract:
The projectile was driven to 2.34 km/s by using 20 mm diameter two-stage light gas gun and impacted with a target to deliver a shock wave into 45 steel sample material. The micro-hardness and micro-structure of the shock wave processed 45 steel were analyzed. The observed results indicate that twins of cemetite in pearlite and high density disloctions to selected zones show that there exist two phases in ferrite of shock wave-processed 45 steel; One is phase of ferrite, and the other remains to be identified latter.

Theoretical Calculation of the Resistivity of Teflon under Shock Loading

ZHANG Guan-Ren

1993, 7(4): 260-264 . doi: 10.11858/gywlxb.1993.04.004

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Abstract:
The resistivity of Teflon under shock loading is calculated theoretically by means of the Mott and Jones' formula with the addition of its equation of state. The results are compared with the published experimental data. Although they may be in good accord, some mechanisms about the decrease of polymerization number of the Teflon with the increase of shock pressure are still unknown, so the theory is partly phenomenological.

Explosive Welding of Amorphous Alloy Ribbons

LI Xiao-Jie, ZHANG Kai, YANG Wen-Bin, XI Jin-Yi, SUN Ming

1993, 7(4): 265-271 . doi: 10.11858/gywlxb.1993.04.005

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Abstract:
Amorphous alloys or metallic glass belongs to a novel class of rapidly solidified alloys, well known for their amorphous structures and excellent properties. Usually, it can only take a very limited number of shapes; thin ribbon, wires or powders. This limitation becomes a major barrier against the spread of the alloys over a wide industrial field. For this reason, a means is necessary to obtain block amorphous alloy. In this paper, the feasibility of bonding amorpious ribbons by explosive means is demonstrated. First, a single ribbon was welded onto a mild steel plate, second, the cladding of 20~200 layers of Fe78B13Si6 and Fe40Ni40P14B6 amorphous ribbons, both of them are 25 m thick and 10 cm wide, were made into tube samples and plate samples. Optical microscope observation and X-ray diffraction analysis were used to check these samples. Results show that the amorphous structure of the alloys still holds after being explosively welded and the welding quality is excellent. Some ribbons initially having crystalline surfaces were also welded, we found that their originally existed -Fe peak disappeared after the explosive welding. This reveals that fusion and rapid cooling occurred at the interfaces between the ribbons during the processing. Finally, it suggests that the deformation of amorphous alloy at lower strain rate is similar to that at commonly used strain rate, but at high strain rate the alloy will show a viscous deformation.

The Interface Instability of the Flyer Driven by Explosion

WANG Wen-Qiang

1993, 7(4): 272-278 . doi: 10.11858/gywlxb.1993.04.006

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Abstract:
The interface instability of a flyer driven by one dimensional or by sliding explosive detonation was studied. The computational results for one dimensional driving are in accord with the experimental results. For sliding explosion, however, there exist no experimental results to compare with, only the computational result is given, which shows a phase shift accompanying with an amplitude increasement due to the Helmholtz instability. Both the flyer and the detonation products were considered as the ideal and incompressible fluid. From the mass and momentum equations and the interface continuation conditions, the relative differential equations were deduced via the method of small perturbation, and then resolved numerically.

A Study on the Catalytic Mechanism of Fe-Based Alloy Diamond Growth

HAO Zhao-Yin, LIU Mi-Lan, CHEN Yu-Fei

1993, 7(4): 279-285 . doi: 10.11858/gywlxb.1993.04.007

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Abstract:
The change of the 3d shell electrons of Fe-based alloys at high pressure and temperature has been measured by using electron energy spectra and Mossbauer spectra, which reveals the bond reaction between the unpaired electrons in the 3d shell of Fe atoms and the 2Pz electrons of carbon atoms in synthetic diamond.

Experimental Studies of the Dynamic Strain Produced in the Circular Ring Targets Bombarded by Electron Beam

PENG Chang-Xian, CHENG Gui-Gan, XU Jian-Bo, YU Bao-Ming

1993, 7(4): 286-292 . doi: 10.11858/gywlxb.1993.04.008

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Abstract:
The dynamic strain is an important mechanic parameter of the structural response produced in the target structure bombarded by electron beam. In this paper, the experimental studies of the dynamic strain produced in the circular ring targets bombarded by electron beam on FLASH-Ⅱ equipment during the recent years are described. The target material is LY-12 aluminum alloy with thicknesses 2.5~3 mm. The range of energy fluxex on targets is 50~60 J/cm2. The experimental results show that the strain values attained is 1.6104 on the centre of the inner-surface of the bombarded part in the circular rings, while the range of strain is (0.45~0.65)104 on the inner-surface of two sides in the circular rings.

Nucleation and Crystal Growth of Synthetic Diopside-Jadeite Jewelry

ZHAO Ting-He, YAN Xue-Wei, CUI Shuo-Jing, ZHU Yi-Bing

1993, 7(4): 293-300 . doi: 10.11858/gywlxb.1993.04.009

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Abstract:
The effects of the crystalline temperature on the hardness and crystalline degree of synthetic diopside-jadeite were studied in this paper. Diopside-jadeite jewelry synthesized from glass with stoichiometry of 0.4CaMgSi2O6-0.6NaAlSi2O6 was obtained under 4.0 GPa, at the different temperatures from 900~1 900 ℃ and for 60 min. Two different hardness of the same piece of diopside-jadeite synthesized below 1 400 ℃ was caused by either the non-crystalline phase or its heterogeneous structure. The crystal growth and fibre construction of diopside-jadeite were studied by SEM at elevated temperature. The observed result reveals that the increasing temperature elevation is favorable to the formation of high quality diopside-jadeite jewelry that has longer, thicker, and more ordered crystal fibers. Microstructure of diopside-jadeite synthesized at higher temperature (1 450 ℃) is much similar to that of the natural one.

The control of Graphite Component in Diamond Thin Films Growth by the Hot Filament CVD Method

YANG Guo-Wei, MAO You-De, Zhang S G

1993, 7(4): 301-304 . doi: 10.11858/gywlxb.1993.04.010

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Abstract:
The effect of the deposition conditions on the graphite or amorphous carbon component in the formation of diamond thin films by HFCVD method was studied. We found that high CH3COCH3 concentration or low-substrate temperature would cause the graphit or amorphous carbon component of the formed films to increase.

1993 Vol. 7, No. 4

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