材料期刊网

Fe-X-C系马氏体相变时的△G_(Fe-X-C)~(γ→α)为:△G_(Fe-X-C)~(γ→α)=_(xFe)△G_Fe~(γ→α)+_(XC)RT×ln_(γ_C~α/γ_C~γ)+x_i△G_i~(γ→α)+△Ω~(γ→α)其中γ_C~α和γ_C~γ分别表示碳在Fe-X-C系铁素体和奥氏体内的活度系数.对Fe-Ni-C和Fe-Cr-C系所求得的M_S值和实验值很好符合.碳在Fe-X-C系的活度值及对奥氏体的强化作用主要决定Fe-X-C系的M_s值.碳是决定Fe-X-C系相变驱动力的主要元素.

The △G_(Fe-X-C)~(γ→α) in the martensitic transformation in Fe-X-C system is sugges-ted as: △G_(Fe-X-C)~(γ→α)=x_(Fe)△G_(Fe-X-C)~(γ→α)+x_C RT lnγ_C~α/γ_C~γ+x_i△G_i~(γ→α) +△Ω~(γ→α)where γ_C~α and γ_C~γ are activity of carbon in Fe-X-C ferrite and austenite respec-tively. The M_s of Fe-Ni-C and Fe-Cr-C obtained in present work are in goodagreement with the experimental results, showing that the above equation inavailable and convenient for application. The M_s of Fe-X-C system mainlydepends upon the activity of carbon in Fe-X-C and the strengthening effect onaustenite and carbon play an important role to determine the driving force of themartensite transformation in Fe-X-C.