APPLICATION OF THE TOMOGRAPHIC ATOM-PROBE TO SELECTED PROBLEMS IN MATERIALS SCIENCE

Field-Ion Microscopy (FIM), equipped with a time of Right detection fa cility (Atom Probe APFIM) has been established as a sensitive analytic al method for the investigation of the local chemical compositions on nanometer scales. Because of its high in-depth resolution of a few ten ths of a nanometer, the magnification of some 10(7), and the equal det ection sensitivity for all elements, this method has helped to solve k ey problems in surface science, materials research and materials engin eering. The newly developed Tomographic Atom Probe (TAP) is equipped w ith a position sensitive detection system and is able to provide spati ally resolved information in real space on the chemical microstructure of materials and compounds with atomic resolution. The sampled volume is about two orders of magnitude larger than that usually analysed wi th the APFIM. The extended set of data collected by the TAP is stored and may be treated with special visualising tools. Three dimensional i mages can be created, which include all the information on microstruct ure and chemical composition of the sampled volume. The paper demonstr ates the capability of the TAP by presenting results from two investig ations regarding phase separation and characterization of layer struct ures, respectively. For the first category TAP images of the time evol ution of the decomposition of the Cu44.7Ni47.3Fe8 alloy during thermal ageing at 773 K are discussed. For the second one, results on the str ucture of the interfaces of sputter deposited Ni/Zr multilayers are tr eated. Such layers appear to be amorphous already after room temperatu re preparation. The thermal stability of Cu/Pd interfaces in sputter d eposited multilayers is discussed with regard to the determination of interdiffusion coefficients from these data.