This work describes the application and usefulness of the focused ion
beam (FIB) technique for the preparation of transmission electron
microscopy (TEM) samples from metal matrix composite materials. Results
on an Al/diamond composite, manufactured by the squeeze casting
infiltration process, were chosen for demonstration. It is almost
impossible to prepare TEM specimens of this material by any other
conventional method owing to the presence of highly inhomogeneous
phases and reinforcement diamond particles. The present article gives a
detailed account of the salient features of the FIB technique and its
operation. One of the big advantages is the possibility to prepare
site-specific TEM specimens with high spatial resolution. The artifacts
occurring during the specimen preparation, for example, Ga-ion
implantation, curtain effects, amorphous layers, bending of the
lamella, or different milling behaviors of the materials have been
discussed. Furthermore, TEM examination of the specimens prepared
revealed an ultrafine amorphous layer of graphite formed at the
interface between the Al and diamond particles that may affect the
interfacial properties of the composite materials. This may not have
been feasible without the successful application of the FIB technique
for production of good quality site-specific TEM specimens.