INTERNAL OXIDATION OF CU-FE .2. THE MORPHOLOGY OF OXIDE INCLUSIONS FROM THE MINIMIZATION OF ELASTIC MISFIT ENERGY

Two types of iron-oxides, both with cubic spinel structure occur simultaneously during internal oxidation of Cu-Fe and form plates on different habit planes of the matrix. Khachaturyan's theory [Theory of Structural Transformations in Solids. Wiley, New York (1983)] for the elastic energy of coherent inclusions was applied to the present case and both habit planes were predicted correctly on the grounds of the orientation relations between the crystal lattices of matrix and precipitates. Moreover, the effect of uncertainties in the numerical values of misfit strain and elastic constants was explored and the result was found to be stable within reasonable variations of these parameters. This shows that the morphology of iron oxides in internally oxidized Cu-Fe is mainly due to elastic misfit strain.