Aluminum Deoxidation Equilibrium in Liquid Fe-36%Ni Alloy

Abstract

For thermodynamic prediction, the deoxidation equilibrium of aluminum in Fe-36%Ni alloy was investigated by employing a cold crucible under an Ar gas atmosphere at 1 773 K. The interaction parameters between aluminum and oxygen by taking liquid Fe-36%Ni alloy as the basis (i.e., solvent) are evaluated as follows:

e_O^Al = -3.8, r_O^Al = -0.9, e_Al^O = -6.4, r_Al^O = 700, r_Al^{Al, O} = 3.1, r_O^{Al, O} = 833

within the composition range of [Al]<1 mass%.
The equilibrium constant for reaction 2Al_{(in Fe-36%Ni)}+3O_{(in Fe-36%Ni)} = Al₂O_3(s) was obtained in the temperature range of 1773 to 1973 K by using data from the present study and from previous works reported:

log K_AO = 0.58−24460/T

The deoxidation equilibrium of aluminum in Fe-36%Ni can thus be thermodynamically described in the range of [Al]<1 mass% using both the first and second order interaction parameters as well as the equilibrium constant determined in this study.