ELECTRON-MICROSCOPY AND DIFFRACTION STUDIES ON THE EARLY STAGE OF CRYSTALLIZATION OF FE84B16 GLASS

The early stage of the alpha -iron precipitation in Fe//8//4B//1//6 glass has been studied by means of selected area electron diffraction and microscopy. Due to the large lattice parameter contraction or dilatation for each of the alpha -iron precipitates occupations of boron atoms on both of the substitutional and interstitial sites were found possible in the small precipitates. Around 10 at. % of boron was presumed to dissolve in the alpha -iron precipitates. It was found that the lattice parameter of the precipitate approached that of pure alpha -iron as the precipitate size increased. A structural decomposition mechanism is proposed on the basis of the measured lattice parameters and the high-resolution lattice images of the alpha -iron precipitates.