Thermodynamics for chemical vapor synthesis （CVS） of Nb nanopowder in NbCl5-H2-Ar system was investigated by using FactSage software. The validation experiments were conducted to confirm the thermodynamics points. T...Thermodynamics for chemical vapor synthesis （CVS） of Nb nanopowder in NbCl5-H2-Ar system was investigated by using FactSage software. The validation experiments were conducted to confirm the thermodynamics points. The results indicate that under the atmospheric pressure, the reduction approach from NbCl5（g） to Nb（s） is a stage-wise process with the formation of complex sub-chlorides, and is controllable at low hydrogen ratio （mole ratio of n（NbCl5）：n（H2）＆lt;1：180） and low temperature （＆lt;1050 ＆#176;C）. Furthermore, a reasonable amount of inert loading gas is favorable to increase the reduction ratio of NbCl5 and the powder yield. The as-synthesized Nb nanopowder with the homogeneous size of 30-50 nm and the powder yield of 85% （mass fraction） is obtained by the CVS process under n（NbCl5）：n（H2）：n（Ar）=1：120：1 and 950 ＆#176;C with the NbCl5 reduction rate of 96.1%.展开更多
The optimized descriptions of the phase diagram and thermodynamic properties for Ce-Al system have been obtained from experimental thermodynamic and phase diagram data by means of the computer program THERMO-CALC bas...The optimized descriptions of the phase diagram and thermodynamic properties for Ce-Al system have been obtained from experimental thermodynamic and phase diagram data by means of the computer program THERMO-CALC based on the least squares method, using models for the Gibbs energy of individual phases. The system contains five intermetallic compounds. The calculated standard enthalpies of Ce_3Al, CeAl, CeAl_2, CeAl_3 and Ce_3Al_ 11 are -26.7, -48.9, -48.4, -44.0 and -41.7 kJ/mol, respectively. A consistent set of thermodynamic parameters was derived. The optimized and experimental data are in good agreement.展开更多
The microstructural changes of Fe83Si4B13 amorphous mother alloy during the heating process were investigated by Laser Scanning Confocal Microscopy （LSCM） ,and the phase transformation was determined by the Thermo-C...The microstructural changes of Fe83Si4B13 amorphous mother alloy during the heating process were investigated by Laser Scanning Confocal Microscopy （LSCM） ,and the phase transformation was determined by the Thermo-Calc calculations. The differences in the melting points measured by Differential Scanning Calorimetry （DSC） and LSCM, and those obtained by Thermo-Calc calculations were also discussed. It is found that the melting points measured by DSC and LSCM are relatively similar, whereas the onset and end of the melting temperatures calculated by Thermo-Calc software are higher than those measured by DSC and observed by LSCM.展开更多
基金Project(51102015)supported by the National Natural Science Foundation of China
文摘Thermodynamics for chemical vapor synthesis （CVS） of Nb nanopowder in NbCl5-H2-Ar system was investigated by using FactSage software. The validation experiments were conducted to confirm the thermodynamics points. The results indicate that under the atmospheric pressure, the reduction approach from NbCl5（g） to Nb（s） is a stage-wise process with the formation of complex sub-chlorides, and is controllable at low hydrogen ratio （mole ratio of n（NbCl5）：n（H2）＆lt;1：180） and low temperature （＆lt;1050 ＆#176;C）. Furthermore, a reasonable amount of inert loading gas is favorable to increase the reduction ratio of NbCl5 and the powder yield. The as-synthesized Nb nanopowder with the homogeneous size of 30-50 nm and the powder yield of 85% （mass fraction） is obtained by the CVS process under n（NbCl5）：n（H2）：n（Ar）=1：120：1 and 950 ＆#176;C with the NbCl5 reduction rate of 96.1%.
文摘The optimized descriptions of the phase diagram and thermodynamic properties for Ce-Al system have been obtained from experimental thermodynamic and phase diagram data by means of the computer program THERMO-CALC based on the least squares method, using models for the Gibbs energy of individual phases. The system contains five intermetallic compounds. The calculated standard enthalpies of Ce_3Al, CeAl, CeAl_2, CeAl_3 and Ce_3Al_ 11 are -26.7, -48.9, -48.4, -44.0 and -41.7 kJ/mol, respectively. A consistent set of thermodynamic parameters was derived. The optimized and experimental data are in good agreement.
文摘The microstructural changes of Fe83Si4B13 amorphous mother alloy during the heating process were investigated by Laser Scanning Confocal Microscopy （LSCM） ,and the phase transformation was determined by the Thermo-Calc calculations. The differences in the melting points measured by Differential Scanning Calorimetry （DSC） and LSCM, and those obtained by Thermo-Calc calculations were also discussed. It is found that the melting points measured by DSC and LSCM are relatively similar, whereas the onset and end of the melting temperatures calculated by Thermo-Calc software are higher than those measured by DSC and observed by LSCM.
