Field evaporation behaviour in the γ phase in Ti–Al during analysis in the tomographic atom probe

A Ti–48 at% Al alloy has been successfully investigated, using atom probe field ion microscopy and transmission electron microscopy. After a specific heat treatment, this alloy has a (α2+γ) lamellar microstructure. Using the tomographic atom probe (TAP), it has been possible to image the stacking of superlattice planes of γ and to identify titanium as the highest evaporation field element. In addition, the influence of analysis site on atom probe measurements has been estimated for this phase. A TAP analysis has also made it possible to observe an extremely thin step along a γ/γ interface at a near atomic scale.