高压物理学报

Pressure Effects on Magnetic Properties of La2/3Ca1/3MnO3+ Thin Films

LIU Zhen-Xing, FEI Yang, MENG Xian-Ren, HUANG Kang-Quan

2000, 14(3): 161-165 . doi: 10.11858/gywlxb.2000.03.001

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Abstract:
Pressure effects on LaCaMnO thin films were studied experimentally. The results show that the resistivity and transition temperature of rich-oxygen samples are not sensitive to pressure. Based on the experimental results on the effects of pressure and temperature on CMR LaCaMnO samples, it is found that pressure also has effects on resistivity in the whole temperature range, but the magnetic field just affects the resistivity around transition temperature.

Experimental Scaling of the Melting Curve for Metals under High Pressure

LI Mao-Sheng, CHEN Dong-Quan

2000, 14(3): 166-170 . doi: 10.11858/gywlxb.2000.03.002

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Abstract:
The investigation of melting curve Tm() under high pressures has practical applications both for temperature induced softening of yield strength of materials and for the reasonable partitioning of the hot contributions from that of cold part. In this paper, we make use of the experimental results of shock melting of Al, Cu, Pb and take account of the transition of Grneisen coefficients () from solid state value to liquid-state value, and thus provide the scaling of melting curve Tm() through Lindemann melting law. Since Lindemann law is closely related with the Grneisen coefficient (), the scaling of Tm() by the experiment data of the shock melting temperature is equivalent to the scaling of () by experiment.

Travel Time Measurement in Tungsten Carbide Anvil under High Pressure

ZHOU Wen-Ge, XIE Hong-Sen, LIU Yong-Gang, GUO Jie, XU Zu-Ming

2000, 14(3): 171-175 . doi: 10.11858/gywlxb.2000.03.003

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Abstract:
Travel time in WC anvils was measured using pulse reflect method at room temperature and under cell pressure up to 3.0 GPa. Experimental results indicate that the travel time in the WC anvils decreased linearly with cell pressure. A possible reason for this result is that the anvil was compressed during loading. The relationship between travel time decrease (t/s) and cell pressure (p/GPa) is t=(0.022 330.000 81)p. Compressional wave velocity under high pressure can be corrected using this formula. As an example, compressional wave velocities under high pressure in three rock samples were corrected.

The Equation of State for Condensed Deuterium

CHEN Qi-Feng, CAI Ling-Cang, WANG Wei, FU Qiu-Wei, CHEN Dong-Quan, JING Fu-Qian

2000, 14(3): 176-181 . doi: 10.11858/gywlxb.2000.03.004

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Abstract:
Spectral radiance histories from the shocked deuterium samples were studied experimentally using pyrometer. Hugoniot data and temperatures of deuterium were deduced. The dissociation and ionization equilibrium method was applied to calculate the equation of state and the composition of deuterium (D2, D, D+,D2+, e). The theoretical results are in the agreement with the experimental data.

Study of Stress Wave Propagation in Laminated Media Using MOC

XU Ming-Li, ZHANG Ruo-Qi, ZHANG Guang-Ying

2000, 14(3): 182-188 . doi: 10.11858/gywlxb.2000.03.005

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Abstract:
MOC (method of cell) is a new means of investigating the problem of wave propagation in materials with complex interior unit structure. The MOC can be used to investigate transient waves due to pulse loading as well as harmonic waves. MOC was introduced, then, it was used to simulate the problem of material dynamic responses in order to review the reliability of MOC. Comparison was made between the results obtained from this method and those from propagation matrix technique. The results from MOC are of high accuracy and MOC is easier to program than traditional difference method and finite-element method.

The Numerical Simulation of Electric Response of PZT95/5 Ferroelectric Ceramics Subjected to Shock Loading

HE Yuan-Ji, ZHANG Ya-Zhou, LI Chuan-Lu, WANG Hong-Gang

2000, 14(3): 189-194 . doi: 10.11858/gywlxb.2000.03.006

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Abstract:
A mathematical model of PZT95/5 ferroelectric ceramics subjected to normal explosive shock loading was suggested. The dielectric relaxation and finite resistive of PZT95/5 were taken into account in this model. Electric equations of PZT95/5 in cases of short circuit, resistive, capacitive and inductive loads were derived. The predictions from this model are in good agreement with previous experimental data.

Study of Numerical Simulation for Quasi-Isentropic Compression

HUA Jin-Song, JING Fu-Qian, GONG Zi-Zheng, TAN Hua, XU Nan-Xian, DONG Yu-Bin, CHEN Dong-Quan

2000, 14(3): 195-202 . doi: 10.11858/gywlxb.2000.03.007

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Abstract:
This article describes the numerical simulation for shock compression which is produced by layered flyers impacting target, in which the isentropic curve is calculated by recurrence method. Take water and tantalum for examples, the calculation results show this kind of flyers can produce good effects of quasi-isentropic compression for water and tantalum, and the result for water is in accord with the reference data, the calculation results for the interface velocity between Ta/LiF is in accord with the experimental results. Therefore, the method to obtain quasi-isentropic compression by layered flyers impacting target and the method of numerical simulation for quasi-isentropic compression are reliable.

Damage Evolution of PBX under Simple Tension

LUO Jing-Run, LI Da-Hong, ZHANG Shou-Qi, ZHAO Fang-Fang, ZHAO Yu-Hua

2000, 14(3): 203-208 . doi: 10.11858/gywlxb.2000.03.008

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Abstract:
The nonlinearity of PBX mechanical behaviors under simple tension was treated as the result of damage evolution, and damage parameter was measured experimentally. A damage evolution equation was derived. The prediction from the constitutive relation including elastic damage effect agrees well with the experimental results. Damage character and its measurement method were also discussed.

Ruby Luminescence R-Line Shift under Shock Loading

PENG Qi-Xian, HU Shao-Lou, TAN Xian-Xiang

2000, 14(3): 209-213 . doi: 10.11858/gywlxb.2000.03.009

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Abstract:
Ruby R-line under shock loading was studied using OMA (Optical Multi-channel Analyzer) on one-stage light gas gun. Time synchronism was in nanoseconds. The R-line shift was measured and pressure-shift relationship was determined.

Dynamic Mechanism of Mechanical Crystallization of Amorphous FeMoSiB Alloy

LIU Shu-E, YAO Bin, GUO Xing-Yuan, LIU Li, SU Wen-Hui

2000, 14(3): 214-218 . doi: 10.11858/gywlxb.2000.03.010

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Abstract:
Crystallization processes and mechanism of amorphous (Fe0.99Mo0.01)78Si9B13 (FMSB) alloy induced by mechanical milling were studied. We suggested that local high pressure has influence on mechanical crystallization, and discussed the effect of local high pressure on amorphous crystallization. It was found that crystallization processes and its products of amorphous FMSB alloy were related closely to milling intensity and time. Only a crystallization product, -Fe(Mo,Si) solid solution occurs in the case of lower milling intensity, however, Fe3B and Fe2B phases appear besides the -Fe(Mo,Si) solid solution in the case of higher milling intensity. We suggested that the crystallization mechanism is the co-interaction due to local high pressure and temperature induced by ball collisions. It is also found that mechanical milling has an important influence on both thermal crystallization temperature under normal pressure of amorphous FMSB and thermal crystallization results.

Synthesis of Bulk Samples of Nanorystalline Tungsten

ZHOU Yu-Song, WU Xi-Jun, LI Bing-Han, XU Guo-Liang

2000, 14(3): 219-223 . doi: 10.11858/gywlxb.2000.03.011

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Abstract:
The bulk nanocrystalline samples of the refractory metal tungsten (nano-W), with -phase tungsten and an average grain size of 34 nm, were synthesized using vacuum hot pressing technique under the pressure of 1 GPa and temperature of 570 ℃. The dimensions, density and microhardness of the nano-W are 10 mm1 mm, 88.8% of the theoretical density and 4.8 GPa, respectively. The density and microhardness of nano-W increase with pressure, temperature and time.

Shock Compression of a Kind of Porous Iron

LI Xi-Jun, ZHOU Xian-Ming, WANG Fan-Hou, JING Fu-Qian, SHI Shang-Chun, DONG Shi, HUANG Yue, CHEN Xin-He

2000, 14(3): 224-228 . doi: 10.11858/gywlxb.2000.03.012

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Abstract:
Shock wave velocities in porous iron with initial average density 6.904 g/cm3 were measured using electric pin method in the pressure range of 80 to 160 GPa. The experimental results indicate that the dynamic compressive properties of this porous iron can be described using a linear relation between the shock wave velocity D and the particle velocity up, i.e., D=2.977+1.603up (km/s). The results are in good agreement with LASL data and the value predicted by Wu-Jing theory.

An Exact Solution for Couette Shear Flow

HAN De-Cai, ZHOU Tie-Nong, PAN Yong-Ge

2000, 14(3): 229-234 . doi: 10.11858/gywlxb.2000.03.013

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Abstract:
An exact solution of velocity distribution for Couette shear flow in a non circular conduit with axial symmetry section is obtained in this paper. From the solution, velocity and flow rate for the rectangular section conduit with finite width are obtained, and it is concluded that Couette shear flow is just a special example when the width is just infinite in the rectangular section conduit flow. Further, we analyzed the error of the solution, and the range in which the formula is suitable is given. An appropriate formula which is easy to use in engineering was obtained based on the results.

The Crack Growth Process of Particulate Filled Polymer Monitored by Acoustic Emission

ZHAO Fang-Fang, LUO Jing-Run, TIAN Chang-Jin, JIN Zhou-Geng, HE Ying-Bo

2000, 14(3): 235-240 . doi: 10.11858/gywlxb.2000.03.014

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Abstract:
In this paper, acoustic emission technology was used to monitor the crack initiation and propagation of single edge notched specimen of particulate filled polymer under three-point-bending condition. In the experiments, the initiation and propagation of crack tip were distinctly distinguished, and the damage modes of particulate filled polymer were efficiently identified. The experimental results studied that the initiation and propagation of crack tip can be divided into three periods. SEM results demonstrated that the main fracture mode of the material is the split between filler and matrix.

2000 Vol. 14, No. 3

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