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 simul taneously during internal oxidation of Cu-Fe and form plates on differ ent habit planes of the matrix. Khachaturyan's theory [Theory of Struc tural Transformations in Solids. Wiley, New York (1983)] for the elast ic energy of coherent inclusions was applied to the present case and b oth habit planes were predicted correctly on the grounds of the orient ation relations between the crystal lattices of matrix and precipitate s. Moreover, the effect of uncertainties in the numerical values of mi sfit strain and elastic constants was explored and the result was foun d 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.