SONG Dan
,
DING Jinjun
,
WANG Yandong(Analysis and Testing Center
,
Northeastern University
,
Shenyang 110006
,
China)
金属学报(英文版)
The microstructures of Ti-14Al-21Nb and Ti-14Al-20Nb-2Mo-3.2V(wt%) alloys have been investikated by transmission electron microscopy(TEM).The phase constitution and the orientation relationship between α2and βwere identified by means of the selected area diffraction and the micro-diffraction techniques.Results show that,compared to Ti-14Al-21Nb,the alloying elements Mo and V can greatly increase the fraction of β phase and improve significantly the microstructures of Ti-14Al-20Nb-2Mo-3.2V.The ordered B2 structure is also evident in the residual βgrains of the latter alloy.
关键词:
:microstructure
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null
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Journal of University of Science and Technology Beijing
The failure of a fluid catalysis and cracking unit (FCCU) in a Chinese refinery was investigated by using nondestructive detection methods, fracture surface examination, hardness measurement, chemical composition and corrosion products analysis. The results showed that the failure was caused by the dew point nitrate stress corrosion cracking. For a long operation period, the wall temperature of the regenerator in the FCCU was below the fume dew point. As a result, an acid fume NOx-SOx-H2O medium presented on the surface, resulting in stress corrosion cracking of the component with high residual stress. In order to confirm the relative conclusion, simulated testing was conducted in laboratory, and the results showed similar cracking characteristics. Finally, some suggestions have been made to prevent the stress corrosion cracking of an FCCU from re-occurring in the future.
关键词:
stress corrosion cracking;fluid catalytic cracking unit;dew point;failure
Chinese Physics Letters
The electron paramagnetic resonance spectra of trigonal Mn(2+) centers in ZnNbOF(5)center dot 6(H(2)O) and CoNbOF(5)center dot 6(H(2)O) crystals are studied on the basis of the complete energy matrices for a d(5) configuration ion in a trigonal ligand field. It is demonstrated that the local lattice structure around a trigonal Mn(2+) center has an elongation distortion along the crystalline c(3) axis, and when Mn(2+) is doped in the ZnNbOF(5)center dot 6(H(2)O) and CoNbOF(5)center dot 6(H(2)O) crystals, there is a similar local distortion. From the EPR calculation, the local lattice structure parameters for trigonal Mn(2+) centers in ZnNbOF(5)center dot 6(H(2)O) and CoNbOF(5)center dot 6(H(2)O) are determined.
关键词:
phase-transition;ions;complexes;crystals;spectra;fe-3+;epr
Physica B-Condensed Matter
On the basis of the defect model of trigonal Dy3+-O2- center in CaF2, the EPR parameters (g factors and hyperfine structure constants) for this trigonal center are calculated from the perturbation formulas. In the formulas, the contributions to EPR parameters due to the J-mixing among H-6(J) (J = 15/2, 13/2 and 11/2) states, the mixtures among the states with the same J-value and those between the lowest Kramers doublet Gamma(gamma) and other Kramers doublets Gamma(X) are included. In the calculation, the crystal field parameters are estimated from the superposition model. From the calculation, the EPR g factors g(\\), g(perpendicular to) are reasonably explained and the superposition model intrinsic parameters (A) over bar (2)(F-) and (A) over bar (2) (O2-) with R = 2.366 Angstrom are obtained. (C) 2003 Elsevier B.V. All rights reserved.
关键词:
EPR parameters;crystal-field theory;superposition model;Dy3+;CaF2;electron-paramagnetic-resonance;field parameters;single-crystals;ions
M. Sakane (Department of Mechanical Engineering
,
Faculty of Science and Engineering
,
Ritsumeikan University
,
1-1-1Nojihigashi Kusatsu-shi Shiga
,
525-8577
,
Japan)S. Mukai (Power Reactor and Nuclear Fuel Development Corporation
,
4002 Narita-cho Oarai-cho Ibaragibun Ibaragi
,
311-13
,
Japan)
金属学报(英文版)
This paper describes new methods for biaxial and triaxial creep testing. Biaxial tension and triaxial tension creep testers were developed. The performance of the machines was described and some test results were discussed. Stress biaxiality had almost no effect on the creep deformation and Mises potential was suitable for describing the creep deformation under biaxial and triaxial stress states. Stress biaxiality had a small influence on prolonging creep rupture time under the constant Mises stress condition.A new triaxial tension creep testing method was discussed together with the shape of the triaxial creep specimen.
关键词:
creep
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null
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null
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null
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null
Zhimin ZHOU
,
Yong ZHOU
,
Mingjun WANG
,
Chunsheng YANG
,
Ji'an CHEN
,
Wen DING
,
Xiaoyu GAO
,
Taihua ZHANG
材料科学技术（英文）
Microbridge testing was used to measure the Young's modulus and residual stress of metallic films. Samples of freestanding NiFe film microbridge were fabricated by microelectromechanical systems. Special ceramic shaft structure was designed to solve the problem of getting the load-deflection curve of NiFe film microbridge by the Nanoindenter XP system with normal Berkovich probe. Theoretical analysis of load-deflection curves of the microbridges was proposed to evaluate the Young's modulus and residual stress of the films simultaneously. The calculated results based on experimental measurements show that the average Young's modulus and residual stress for the electroplated NiFe films are 203.2 GPa and 333.0 MPa, respectively, while the Young's modulus measured by the Nano-hardness method is 209.6±11.8 GPa for the thick NiFe film with silicon substrate.
关键词:
Mechanical properties
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金属薄膜
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纳米压痕
H.D. Chen
,
Y.W. Wang
,
J. Xue
金属学报(英文版)
A computer simulation technique for ultrasonic propagation is utilized for the simulation of ultrasonic nondestructive testing (NDT). In this paper, one goal of the simulation is to compute ultrasoniceld radiated by arbitrary transducers into pieces under examination. The other simulates a testing experiment. The simulation approach is based on the model for the computation of the ultrasoniceld in isotropic media radiated from actual NDT transducers. After the eld is known, remaining to be modeled is the interaction between this eld and the scatters (defect) and the echo structure. The model of beam-defect interaction is based on the Kirchho's diffraction approximations theory applied to elastodynamics. We assumed that the incident wave fronts on the defect are plane in the case of a focused immersed transducer and material is isotropic and homogeneous. The simulating results demonstrate that the model in ultrasonic NDT of welds is practical in further research and useful in optimizing testing congurations.
关键词:
ultrasonic testing
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null
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null
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