THE EFFECT OF SUPERSATURATION ON THE INTERNAL OXIDATION OF BINARY-ALLOYS

According to the theory of Bohm and Kahlweit of the internal oxidation of binary A-B alloys, the parabolic rate constant for the formation o f reasonably stable internal BOv oxides as well as the concentrations of O and B at the oxidation front are controlled only by the degree of supersaturation necessary for the nucleation of new oxide particles. The effects of this factor on the previous parameters are calculated f or various values of the solubility product of the oxide and of the di ffusion coefficients of O and B. Moreover, an alternative procedure fo r the calculation of the critical degree of supersaturation behind the precipitation front required for oxide precipitation, which is a func tion of the concentration of the reactants at the internal oxidation f ront, is proposed. A simple modification of Wagner's theory of interna l oxidation is also presented, and its results are compared with those of the treatment by Bohm and Kahlweit. Finally, the limitations of th e two methods are examined.