Effect of Alloying Elements on Stability of Epsilon Iron

抄録

A dilatometric experiment of the fcc\ ightleftarrowshcp martensitic transformation in Fe–Mn–X alloys was made to determine the effects of alloying elements on the Ms^γ→ε and As^ε→γ temperatures. The As^ε→γ temperature was lowered by additions of Al, Co, Cr, Cu, Mo, Nb, Ni, Si, Ti, V, W and C, while the Ms^γ→ε temperature was lowered by alloying the above elements except Co. The parameter ΔG_X^γ⁄εFe which represents the effect of alloying element X on the relative stability of γ-iron and ε-iron near 500°K was evaluated by thermodynamic analysis of the As^ε→γ and Ms^γ→ε data. The value of the parameter ΔG_X^γ⁄εFe changed systematically with the group number in the periodic classification. Another parameter ΔG_X^α⁄εFe for α-iron and ε-iron was derived from the values of ΔG_X^α⁄γFe and ΔG_X^γ⁄εFe, and the parameter was found to change in accordance with the periodic table.