  Needle-shaped atom probe specimens containing a single grain boundary were
produced using the focused ion beam (FIB) of a dual-beam FIB/SEM (scanning
electron microscope) system. The presented specimen preparation approach allows
the unprecedented study of a grain boundary which is well characterised in its
crystallographic orientation by means of the field ion microscope (FIM) and the
tomographic atom probe (TAP). The analysis of such specimens allows in
particular the determination of solute excess atoms at this specific grain
boundary and hence the investigation of the segregation behaviour. The crucial
preparation steps are discussed in detail in the present study for the S 19a
{331} <110> grain boundary of a 40 at.ppm-Bi doped Cu bi-crystal. Transmission
electron microscope (TEM) images and TAP analyses of the atom probe tips
demonstrate unambiguously the presence of the selectively prepared grain
boundary in the apex region of some of the specimens.
