Abstract
Partial molar free energy difference ΔGXα⁄γFe is one of the most important parameters to represent the functions of the alloying elements in steel. This parameter was defined as the free energy change accompanied by transfer of one mole of each alloying element from ferrite to austenite, and the value has been obtained from α⁄γ equilibrium compositions in the Fe–X system. In the present work, the parameters for various alloying elements were evaluated from the data on Msγ→α and Asα→γ temperatures of Fe–Ni–X alloys. The results show that the parameter generally changes depending on temperature, especially near the Curie point of iron, and some of the ferrite stabilizing elements, Cr, Mo, W and V act as austenite stabilizers at low temperature. The considerable temperature dependence of the parameter ΔGXα⁄γFe was considered to be mainly due to the magnetic effect suggested by Zener and Hillert et al.
