Supposing carbon contents of ferrite phases in pearlite precipitating from austenite in multicomponent steel at temperature T and in Fe-C ystem at T' are the same the pearlite formation temperature diference, can ...Supposing carbon contents of ferrite phases in pearlite precipitating from austenite in multicomponent steel at temperature T and in Fe-C ystem at T' are the same the pearlite formation temperature diference, can be calculated from the FeX phase diagrams and the equilibrium temperature Al. Using Tp and Fe-C binary thermodynamic model, the driving forces for phase transformation from austenite to pearlite in multicomponent steels have been successfully calculated. Through the combination of simplified Zener and Hillert's model for pearlite growth with Johnson-Mehl equation, using data from known TTT diagrams, the interfacial energy parameter and activation energy for pearlite formation can be determined and expressed as functions of chemical composition in steels by regression analysis. The calculated starting curves of pearlitic transformation in some commercial steels agree well with the experimental data.展开更多
The present investigation is concerned with the reaction of barium and iron nitrates mixtures using three different molar ratios, 1:1 (Ⅰ), 1:2 (Ⅱ) and 2:1 (Ⅲ) at different temperatures as pointed out from the DTA d...The present investigation is concerned with the reaction of barium and iron nitrates mixtures using three different molar ratios, 1:1 (Ⅰ), 1:2 (Ⅱ) and 2:1 (Ⅲ) at different temperatures as pointed out from the DTA data. The reaction products exhibit 12 compounds namely, Ba(NO3)2, αFe2O3, Fe3O4, BaFeO3, BaFeO2.9, hexagonal BaFeO3-x, tetragonal BaFeO3-x, BaFe2O4, αBaFe2O4, Ba2Fe6O11, Ba5Fe14O26 and BaFe12O19. The formation of these products depend on the molar ratio between the reactants and the reaction temperature. The reaction products were studied by DTA and TG techniques and characterized by X-ray diffraction patterns, magnetic susceptibility data and scanning electron microscopy, SEM.展开更多
Proeutectoid ferrite with carbon content xo precipitating from austenite in a multicomponent steel at temperature T is supposed to be equivalent to proeutectoid ferrite with the same carbon content precipitating from...Proeutectoid ferrite with carbon content xo precipitating from austenite in a multicomponent steel at temperature T is supposed to be equivalent to proeutectoid ferrite with the same carbon content precipitating from austenite in Fe-C binary system at temperature T'.is described as the temperature difference of proeutectiod ferrite formation, and can be calculated from the Fe-X diagrams and the equilibrium temperature A3. By introducing Tf and basing on the thermodynamic model for Fe-C binary alloy, the driving force for phase transformation from austenite to proeutectoid ferrite in multicomponent steels has been successfully calculated. Through the Johnson-Mehl equation and using the data hem known TTT diagrams, the relationship between the chemical composition and the intedecial edenly packeter as well as activation energy for proeutectoid ferrite formation can be calculated. The starting curves of proeutectoid ferritic transformation calculated in this way in some hypo-proeutectoid structural steels agree well with the erperimental data.展开更多
文摘Supposing carbon contents of ferrite phases in pearlite precipitating from austenite in multicomponent steel at temperature T and in Fe-C ystem at T' are the same the pearlite formation temperature diference, can be calculated from the FeX phase diagrams and the equilibrium temperature Al. Using Tp and Fe-C binary thermodynamic model, the driving forces for phase transformation from austenite to pearlite in multicomponent steels have been successfully calculated. Through the combination of simplified Zener and Hillert's model for pearlite growth with Johnson-Mehl equation, using data from known TTT diagrams, the interfacial energy parameter and activation energy for pearlite formation can be determined and expressed as functions of chemical composition in steels by regression analysis. The calculated starting curves of pearlitic transformation in some commercial steels agree well with the experimental data.
文摘The present investigation is concerned with the reaction of barium and iron nitrates mixtures using three different molar ratios, 1:1 (Ⅰ), 1:2 (Ⅱ) and 2:1 (Ⅲ) at different temperatures as pointed out from the DTA data. The reaction products exhibit 12 compounds namely, Ba(NO3)2, αFe2O3, Fe3O4, BaFeO3, BaFeO2.9, hexagonal BaFeO3-x, tetragonal BaFeO3-x, BaFe2O4, αBaFe2O4, Ba2Fe6O11, Ba5Fe14O26 and BaFe12O19. The formation of these products depend on the molar ratio between the reactants and the reaction temperature. The reaction products were studied by DTA and TG techniques and characterized by X-ray diffraction patterns, magnetic susceptibility data and scanning electron microscopy, SEM.
文摘Proeutectoid ferrite with carbon content xo precipitating from austenite in a multicomponent steel at temperature T is supposed to be equivalent to proeutectoid ferrite with the same carbon content precipitating from austenite in Fe-C binary system at temperature T'.is described as the temperature difference of proeutectiod ferrite formation, and can be calculated from the Fe-X diagrams and the equilibrium temperature A3. By introducing Tf and basing on the thermodynamic model for Fe-C binary alloy, the driving force for phase transformation from austenite to proeutectoid ferrite in multicomponent steels has been successfully calculated. Through the Johnson-Mehl equation and using the data hem known TTT diagrams, the relationship between the chemical composition and the intedecial edenly packeter as well as activation energy for proeutectoid ferrite formation can be calculated. The starting curves of proeutectoid ferritic transformation calculated in this way in some hypo-proeutectoid structural steels agree well with the erperimental data.
