The main application areas of atom-probe techniques in physical metallurgy are recieved. Original information provided by this micro-analytical tool in the study of precipitation, ordering phenomena, phase or grain boundaries, and clustering effects are discussed. The investigations, which are given as illustrations, are essentially based on researches that we have conducted on materials developed for aerospace applications (nickel base superalloys, ...) or nuclear energy (duplex stainless steels). A large part of this paper is focussed on experimental requirements, interpretation problems and statistical tools which can used for data analyses. \textcopyright 1992.