Diffusion of 59Fe in γ-TiAl single crystals

Abstract

Diffusion of 59Fe in single crystalline γ-TiAl intermetallic compound has been investigated by the ion-beam sputter-sectioning technique in the temperature range from 1123 to 1303 K. The diffusion coefficients measured in the directions parallel ( D 33) and perpendicular ( D 11) to the [001] axis exhibit significant anisotropy; the diffusion of 59Fe parallel to the [001] direction is faster than that perpendicular to the [001] direction. The activation energy for diffusion of 59Fe parallel to the [001] direction is smaller than that perpendicular to that direction. The anisotropy of 59Fe diffusion was opposite to that of 44Ti self-diffusion. It is suggested that this anisotropy is related to site occupation of Fe in TiAl and the jumps of atoms through vacancy jumps.