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

International audienceA 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 α2plates in γmhave been analysed with one-dimensional AP microscopy and observed in TEM. Their formation in γmseems to be induced by the presence of oxygen, which is rejected from the γmphase during the massive transformation. The influence of chemical order on the field evaporation process has also been studied for the Ll0-ordered structure of the γmphase. \textcopyright 2002 Elsevier Science B.V. All rights reserved