HUANG Kelong
,
SHU Wanyin
,
DING Dunhuang
,
LIU Guogen
,
DONG Ping
,
Central South University of Technology
,
Changsha
,
China HUANG Kelong
,
Lecturer
,
Department of Chemistry
,
Central South University of Technology
,
Changsha 410083
,
China
金属学报(英文版)
In order to clarify the mechanism and the complex formed in the extraction of divalent Mn by alkylphosphonic acid monoester, the solid complex has been prepared by mono (2-ethylhexyl)-2-ethylhexyl phosphate, HEH(EH)P, HA with divalent Mn. The elemental analysis, magnetic susceptibility and thermogravimetry have been determined for the solid complex of HEH(EH)P-Mn(II) and the infrared spectrum has been carried out in comparison to the extractant HEH(EH)P. The extracted compound has also been studied by electronic and electron spin resonance spectroscopy in octane solvent and solid state at room temperature. On the basis of the measurements, it is concluded that the structure of the solid polymeric species MnA_2 is in a tetrahedral arrangement.
关键词:
solvent extraction mono (2-ethylhexyl)-2-ethylhexyl phosphate
,
null
,
null
Q.R. Zhang
,
Y.G. Li and Z. Fang (Department of Chemistry
,
Central South University of Technology
,
Changsha 410083
,
China)(Department of Chemistry
,
Central South University of Technology
,
Changsha 410083
,
China)(Department of Chemistry
,
Central South University of Technology
,
Changsha 410083
,
China)
金属学报(英文版)
In orber to calculate the activity coefficients of water in the aqueous solution systems of double electrolytes, HCl and MCln (M=Ni, Cu,Na and Fe), a simplified regular solution model has been derived based on the assumption that the electrolytes in the aqueous solution are treated as independent particles instead of their ion forms, and that the interaction of the component pair HCl-MCln in the aqueous solution is very weak as compared with the component pairs HCl-H2O and H2 O-MCln. The interchange energies of the component pairs in the discussed systems, ωWCl-H2o, ωH2o-NiCl2,ωH2o-CuCl2, ωH2o-NaCl and ωH2O-FeCl3, have been evaluated from the experimental data to be-69800, -212600, -90550, -42450 and -198310J·mol-1.
关键词:
solution model; interchange energy; electrolyte solution
FANG Zheng
,
ZHANG Hengzhong
,
ZHANG Pingming
,
HUANG Shengtang
,
GUO Li and HU Guoqiang(Department of Chemistry
,
Central South University of Technology
,
Changsha 410O83
,
China)Manuscript received 18 Jnly 1995
,
in revised form 14 April 1996
金属学报(英文版)
A set of thermo-electrochemical (TEC) equations for the cell and half-cell reactions has been derived. Is is shown that the difference between the enthalpy change determined by TEC technology and the one calculated with the current thermodynamic data of ions of any half-cell reaction in electochemical systems is coastant. The absolute entrupy change of the standard hydrogen electrode reaction was determined to be 85.2 J.K-1 .mol-1 at room temperature:
关键词:
: thermo-electrochemistry
,
null
,
null
M.W. Li
,
R.Z. Tang and W.X. Li (Department of Materials Science and Engineering
,
Central South University of Technology
,
Changsha 410083
,
China)
金属学报(英文版)
Starting from elemental powders, complete MoSi2 powder forms abruptly between 3.5and 4 h during mechanical alloying (MA) of the Mo-66 at.% Si powders. Continuous milling of this MoSi2 Phase leads to a nanocrystalline powder and amorphizationtransformation takes place after 100 h milling. Howeven MA of the Mo-37.5 at.%Si powders does not result in the formation of the Mo5Si3 crystalline phase, but the formation of a Mo(Si) supersaturated solid solution (SSS) and a completely amorphots phase after 5 h and 70 h milling, respectively. The free energy of the Mo-Sisystem has been calculated and it has been found that there is no driving force for the amorphization reaction under normal conditions. The amorphization by MA of the Mo-Si system is attributed to a solid-state amorphization reaction in which defects and a very fine grain size induced during milling process may raise the free energy of the crystalline intermetallic phase (for MoSi2) or the Mo(Si) supersaturated solid solution (for Mo5Si3) above that of the amorphous phase.
关键词:
mechanical alloying
,
null
,
null
H. Zhang
,
Y. Y. Liu
,
D. S. Peng and C. K. Wang (Department of Materials Science and Engineering
,
Central South University of Technology
,
Changsha 410083
,
China)
金属学报(英文版)
Continuous thermo-mechanical processing (CTMP) of 6201 aluminum alloy was simulated on Gleeble-1500. The deformed specimens were analyzed by the observation of TEM and the measurement of hardness. It was shown that rapid solid solution and aging treatment can be effectively combined in one procedure by the strain induced during CTMP. The deformation temperature is ranging from 540* C to 300* C, the hardness increases directly before the 6th pass followed by a slight drop, the amount of precipitates increases with the holding time after deformation. Uniformly distributed and stabilized Mg2Si precipitates, as well as dislocation substructure can be observed on deformed specimens which have been subsequently held at 300℃ for 60 seconds.
关键词:
6201 aluminum alloy
,
null
,
null
,
null
,
null
Y.H. He
,
B. Y. Huang
,
Y. Liu and Y.X. Liu (Powder Metallurgy Research Institute
,
Central South University of Technology
,
Changsha 410083
,
China)
金属学报(英文版)
The effects of a new technology, multi-step thermo-mechanical treatment, on the microstructure, deformation substructure and mechanical properties at ambient and elevated tempemture of can-forged Ti-33 Al-3 Cr-0.5Mo (wt%) Alloy were investigated.The results show that, after multi-step thermo-mechanical treatment of can-forged specimens, homogeneous, fine microstructures can be obtained in the whole TiAl-based alloy specimens. Furthermore, the specimen with homogeneous and fine full lamellae microstructure demonstrutes excellent comprehensive mechanical properties at ambient and elevated temperature.
关键词:
TiAl-based alloy
,
null
,
null
