PREPARATION OF FE-SI SINGLE-CRYSTALS AND BICRYSTALS FOR DIFFUSION EXPERIMENTS BY THE ELECTRON-BEAM FLOATING-ZONE TECHNIQUE

An electron-beam floating zone melting technique has been used to grow oriented single crystals and bicrystals of Fe-Si alloys with 6, 10, 1 2 and 14 at% Si. Procedures for the preparation of monocrystalline and bicrystalline seeds as well as for the growing of single crystals and bicrystals of these alloys are described. Studies of chemical composi tion of the bicrystalline specimens with aid of electron probe microan alysis revealed a homogeneous distribution of the main components. The behaviour of Fe-Si bicrystals in contact with a Zn-rich melt has been investigated. The wetting of grain boundaries by the melt and differe nt types of Zn diffusion along the grain boundaries in several concent ration intervals with a sharp transition from high to low diffusivity have been observed.