Atom probe study of phase transformations in a Ti–48 at.% Al alloy

A Ti–48 at.% Al alloy has been investigated by means of atom probe field ion microscopy (APFIM) and transmission electron microscopy (TEM). Atom probe (AP) techniques have been used to determine the composition of the massive γ-phase (γm). The ultrafine lamellar structure, which consists of α2- and γ-lamellae, has been also characterised. The α2 plates in γm have been analysed with one-dimensional AP microscopy and observed in TEM. Their formation in γm seems to be induced by the presence of oxygen, which is rejected from the γm phase during the massive transformation. The influence of chemical order on the field evaporation process has also been studied for the L10-ordered structure of the γm phase.