By the application of Chou's new geometry model and the available data from binary Fe?Mn, Fe?Si and Mn?Si systems, as well as SGTE DATA for lattice stability parameters of three elements from Dinsdale, the Gibbs f...By the application of Chou's new geometry model and the available data from binary Fe?Mn, Fe?Si and Mn?Si systems, as well as SGTE DATA for lattice stability parameters of three elements from Dinsdale, the Gibbs free energy as a function of temperature of the fcc(γ) and hcp(ε) phases in the Fe?Mn?Si system is reevaluated. The relationship between the Neel temperature of the γ phase and concentration of constituents in mole fraction,T N γ =67x Fe+540x Mn+x Fe x Mn[761+689(x Fe?x Mn)]?850x si, is fitted and verified by the experimental results. The critical driving force for the martensitic transformation fcc(γ)→hcp(ε), ΔG C γ→ε , defined as the free energy difference between γ and ε phases atM s of various alloys can also be obtained with a knownM s . It is found that the driving force varies with the composition of alloys, e. g. ΔG C γ→ε =?100.99 J/mol in Fe?27.0Mn?6.0Si and ΔG C γy→ε =?122.11 J/mol in Fe?26.9Mn?3.37Si. The compositional dependence of critical driving force accorded with the expression formulated by Hsu of the critical driving force for fcc(γ)→hcp(ε) transformation in alloys with low stacking fault energy (SFE), i. e. ΔG C γ→ε =A·γ+B, where γ is the stacking fault energy (SFE) andA andB are constants related to materials.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.59671023).
文摘By the application of Chou's new geometry model and the available data from binary Fe?Mn, Fe?Si and Mn?Si systems, as well as SGTE DATA for lattice stability parameters of three elements from Dinsdale, the Gibbs free energy as a function of temperature of the fcc(γ) and hcp(ε) phases in the Fe?Mn?Si system is reevaluated. The relationship between the Neel temperature of the γ phase and concentration of constituents in mole fraction,T N γ =67x Fe+540x Mn+x Fe x Mn[761+689(x Fe?x Mn)]?850x si, is fitted and verified by the experimental results. The critical driving force for the martensitic transformation fcc(γ)→hcp(ε), ΔG C γ→ε , defined as the free energy difference between γ and ε phases atM s of various alloys can also be obtained with a knownM s . It is found that the driving force varies with the composition of alloys, e. g. ΔG C γ→ε =?100.99 J/mol in Fe?27.0Mn?6.0Si and ΔG C γy→ε =?122.11 J/mol in Fe?26.9Mn?3.37Si. The compositional dependence of critical driving force accorded with the expression formulated by Hsu of the critical driving force for fcc(γ)→hcp(ε) transformation in alloys with low stacking fault energy (SFE), i. e. ΔG C γ→ε =A·γ+B, where γ is the stacking fault energy (SFE) andA andB are constants related to materials.
