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Forming and growing mechanisms of homogenization-solution pores in a single crystal superalloy

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Rare Metals 2018年第5期37卷 399-406页

作者： Xiao-Dai Yue Jia-Rong Li Xiao-Guang Wang Zhen-Xue Shi Science and Technology on Advanced high temperature Structural Materials Laboratory Beijing Institute of Aeronautical Materials

The forming and growing mechanisms of homogenization-solution pores in a single crystal superalloy were investigated. The microstructures were observed with optical microscope （OM） and field emission microscope （FEM） after homogenization-solution heat treated at 1328℃ and 1350 ℃ for 2 h, 6 h and 9 h. Results indicate that when heat treated at 1328 ℃, pores appear at the interface of eutectic and matrix at first and then leave in the matrix with the shrink of eutectic. When heat treated at 1350 ℃, incipient melting happens at first, and some of them have a pore in the center. After that, with the homogenization-solution process, incipient melting microstructure fades away gradually. By analyzing the results with thermodynamics and kinetics methods, it is concluded that some pores nucleate during directional solidification and then become larger and visible during homogenization-solution heat treatments; some pores are generated by incipient melting, yet such pores are difficult to be distinguished from other pores; imbalanced elements cross-diffusion induces to the forming and growing of pores too, and such imbalanced diffusion also plays an important part on the growth of all preexisting pores.

关键词： Single crystal superalloy Pore Homogenization Solution Heat treatment Incipient melting

Double detonation drivers for a shock tube/tunnel

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Science China(Physics,Mechanics & Astronomy) 2004年第4期47卷 502-512页

作者： CHEN Hong FENG Heng YU Hongru high temperature Gas Dynamics Laboratory Institute of Mechanics Chinese Academy of SciencesBeijing 100080 China High Temperature Gas Dynamics Laboratory Institute of Mechanics Chinese Academy of SciencesBeijing 100080 China High Temperature Gas Dynamics Laboratory Institute of Mechanics Chinese Academy of SciencesBeijing 100080 China

ARecent progress on detonation drivers is reviewed. Performances of the forward detonation driver and backward detonation driver have been observed. To eliminate occurrence of a Taylor wave following the detonation wave in the primary driver and to improve the performance of the detonation driver, an additional backward detonation driver was proposed to attach to the end of the forward detonation driver. When the ratio of the initial pressures between the additional and the primary drivers becomes larger than or equal to a critical value, the Taylor wave will disappear, and thus a homogeneous driving gas with high pressure and high temperature can be generated. Furthermore, an over-driving detonation wave will be also obtained, which can increase the driving capability.

关键词： gaseous detonation, shock tube, shock tunnel.

An experimental determination of W,Nb,and Ta partition coefficients between P-rich peraluminous granitic melt and coexisting aqueous fluid

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Chinese Journal Of Geochemistry 2015年第2期34卷 194-200页

作者： Yong Tang Hui Zhang Laboratory for high temperature and high Pressure Study of the Earth's Interior Institute of GeochemistryChinese Academy of Sciences

The partition coefficients of W,Nb,and Ta between the P-rich peraluminous granitic melt and the coexisting aqueous fluid were determined at 800-850 °C and 0.5-1.5 *** experimental results showed that the partition coefficients D_w,D_(Nb) and D_(Ta)(D_i^(v/m) = C_i^V/C_i^m,where C_i^V and C_i^m denote the concentrations of an element,i,in the aqueous fluid and the melt,respectively) were less than *** partition coefficients were affected by pressure,but there was no evidence for the complexation of P2O5 with these elements in the granitic melt or aqueous fluid,except for with W in the *** results showed that W,Nb,and Ta tended to partition into the granitic melt and,in the late period of crystallization of P-rich magma,they formed independent minerals.

关键词：分配系数实验测定水流体过铝质熔体 Nb 共存钽

EXPERIMENTAL INVESTIGATION ON THE CHAOTIC PHENOMENA IN THE WAKE OF A NATURAL THERMAL CONVECTION FLOW

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Acta Mechanica Sinica 2000年第2期16卷 121-127页

作者：林贞彬郭大华余西龙朱进生 Laboratory of high temperature of Gas Dynamics Institute of Mechanics Chinese Academy of Sciences Beijing China 100080

Chaotic phenomena in the wake of thermal convection flow fields above a heating flat plate were investigated experimentally. A newly developed electron beam fluorescence technique (EBF) was used to simultaneously measure density fluctuation at 7 points in a cross section above the plate. Correlation dimensions, intermittence coefficients, Fourier spectrum have been obtained for different Grashof numbers. Spatial distribution of correlation dimensions are presented. The experimental result shows that there is a certain relationship between the density fluctuation and the Gr number. And time-spacial characteristic of chaos evolution is also given.

关键词： thermal convection flow transition chaos electron beam fluorescence technique

AN INVESTIGATION OF ELECTROMAGNETIC WAVE PROPAGATION IN PLASMA BY SHOCK TUBE

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Acta Mechanica Sinica 2004年第3期20卷 212-218页

作者：竺乃宜李学芬黄立舜余西龙杨乾锁 Laboratory of high temperature Gas Dynamics Institute of MechanicsChinese Academy of SciencesBeijing 100080China

This paper presents the electromagnetic wave propagation characteristics in plasma and the attenuation coefficients of the microwave in terms of the parameters n_e,v,ω,L,ω_*** φ800 mm high temperature shock tube has been used to produce a uniform *** order to get the attenuation of the electromagnetic wave through the plasma behind a shock wave,the microwave transmission has been used to measure the relative change of the wave *** working frequency is f=(2～35)GHz(ω=2πf,wave length λ=15 cm～8 mm).The electron density in the plasma is n_e=(3×10^(10)～1×10^(14))cm^(-3).The collision frequency v=(1×10~8～6×10^(10))*** thickness of the plasma layer L=(2～80)*** electron circular frequency ω_b=eBo/m_e,magnetic flux density B_0=(0～0.84)*** experimental results show that when the plasma layer is thick (such as L/λ(?)10),the correlation between the attenuation coefficients of the electromagnetic waves and the parameters n_e,v,ω,L determined from the measurements are in good agreement with the theoretical predictions of electromagnetic wave propagations in the uniform infinite *** the plasma layer is thin(such as when both L and λ are of the same order),the theoretical results are only in a qualitative agreement with the experimental observations in the present parameter range, but the formula of the electromagnetic wave propagation theory in an uniform infinite plasma can not be used for quantitative computations of the correlation between the attenuation coefficients and the parameters n_e,v,ω,*** fact,if ωω_p,v^2(?)ω~2(just v≈f),the measurements are much larger than the theoretical ***,we have measured the electromagnetic wave power attenuation value under the magnetic field and without a magnetic *** result indicates that the v

关键词： microwave plasma shock tube

Microstructure and stress-rupture property of an experimental single crystal Ni-base superalloy with different heat treatments

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Rare Metals 2014年第2期33卷 144-148页

作者： Jing-Yang Chen La-Mei Cao Ming Xue Li-Jun Liu Science and Technology on Advanced high temperature Structural Materials Laboratory Beijing Institute of Aeronautical Materials

The influence of heat treatment on the microstructure and stress-rupture property at 1,100 °C/140 MPa was investigated in a 5.0 wt% Re containing experimental single crystal Ni-base superalloy. The results indicate that the γmorphology is nearly cuboidal in the dendrite core after conventional heat treatment. The lattice misfit of alloy becomes more negative after modified heat treatment and results in more cuboidal γ precipitates than that after conventional heat treatment. The increased stress-rupture life after modified heat treatment is attributed to higher γ volume fraction, more negative lattice misfit, well-rafted structure, and narrower c channel width.

关键词： Superalloy Heat treatment γprecipitate Lattice misfit Stress-rupture property

Preparation and properties of Ba_3Zn_ZCo_(2-Z)Fe_(24)O_(41)/SiO_2 microcrystalline glass ceramics

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中国有色金属学会会刊：英文版 2004年第1期14卷 170-174页

作者：张海军贾晓林姚熹张良莹 high temperature Ceramics institute Zhengzhou University Functional Materials Research Laboratory Tongji University

Ba 3Zn Z Co 2 Z Fe 24 O 41 /SiO 2 ( Z varies from 0.0 to 1.2 in step of 0.4) microcrystalline glass ceramics were prepared by citrate sol gel process at 1 200 ℃ in the system of BaO Fe 2O 3 CoO ZnO SiO 2. The samples were characterized by X ray diffraction (XRD) and scanning electron microscopy (SEM). The complex dielectric constant and complex permeability of Ba 3Zn Z Co 2 Z Fe 24 O 41 /SiO 2 microcrystalline glass ceramics were measured in the range of 0.16.0 GHz by transmission/reflection coaxial line method. The natural resonance phenomenon was observed in μ ″ spectra for all the Ba 3Zn Z Co 2 Z Fe 24 O 41 /SiO 2 microcrystalline glass ceramics, which was closely affected by the substitution of Zn 2+ ion.

关键词：微晶玻璃陶瓷 Ba3ZnzCo2-zFe24O41/SiO2 制备性能 XRD SEM 溶胶-凝胶

Shear viscosity of aluminum studied by shock compression considering elasto-plastic effects

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Chinese Physics B 2014年第9期23卷 331-334页

作者：马小娟郝斌斌马海霞刘福生 institute of high temperature and high Pressure Physics Key Laboratory of Advanced Technologies of Materials of the Ministry of EducationSouthwest Jiaotong University

The strength always exists before the material melts. In this paper, the viscoelastic-plastic model is applied to improve the finite difference method, and the numerical solutions for the disturbance amplitude damping behavior of the sinusoidal shock front in a flyer-impact experiment are obtained. When the aluminum is shocked to 101 GPa, the effect of elasto-plasticity on the zero-amplitude point of the oscillatory damping curve is the same as that of viscosity when η= 700 Pa.s, and the real shear viscosity coefficient of the shocked aluminum is determined to be about 2800±100 Pa.s. Comparing the experiment data with the numerical results of the viscoelastic-plastic model, we find that the aluminum is close to melting at 101 GPa.

关键词： shock shear viscosity elastoplasticity

Shock Tube Studies on Recombination Kinetics of Sodium Ion with Electron

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Chinese Physics Letters 2001年第2期18卷 289-291页

作者： WANG Su CUI Ji-Ping HE Yu-Zhong FAN Bing-Cheng WANG Jing Laboratory of high temperature Gas Dynamics Institute of MechanicsChinese Academy of SciencesBeijing 100080

he ionization kinetics of sodium diluted in argon is studied in a shock tube,in which the test gas mixture is ionized by a reflected shock wave and subsequently quenched by a strong rarefaction wave.A Langmuir electrostatic probe is used to monitor the variation of the ion number density at the reflection shock wave *** working state of the probe is in the near free fall region and a correction for reduction of the probe current due to elastic scattering in the probe sheath is *** the temperature range of 800 to 2600 K and in the ambience of argon gas,the three-body recombination rate coefficient of the sodium ion with electron is determined:3.43 × 10^(-14)T-^(3.77)cm^(6).s^(-1).

关键词： diluted correction Electron