While searching the internet for “nanotechnology,” I was not surprised to find many definitions. Two of these are as follows: (1) nanotechnology is the development and use of devices that have a size of only a few nanometers; and (2) nanotechnology can best be considered as a “catch-all” description of activities at the level of atoms and molecules that have applications in the real world. While nanotechnology is usually focused on the building of structures at the atomic scale, the characterization of such structures should also be considered as nanotechnology. At the Microscopy and Microanalysis 2002 Meeting in Quebec City, together with Tom Kelly and Mike Thompson, I organized a symposium entitled “Advances in Nanoscale Technology.” The response to this symposium was impressive, with 32 contributed and 7 invited presentations. Some of these presentations concentrated on atom probe field ion microscopy and form the basis for the invited contributions in this special issue of Microscopy and Microanalysis.

This work reviews recent research on the design and control of interfaces in engineering nanomaterials. Four case studies are presented that demonstrate the power of a multimodal approach to the characterization of different types of interfaces. We have used a combination of conventional, high resolution, and analytical transmission electron microscopy, microbeam electron diffraction, and three-dimensional atom probe to study polymer–clay nanocomposites, turbine rotor steels used for power generation, multicomponent aluminum alloys, and nanocrystalline magnetic materials.

Atom probe tomography is a technique for the nanoscale characterization of microstructural features. Analytical techniques have been developed to estimate the size, composition, and other parameters of features as small as 1 nm from the atom probe tomography data. These methods are outlined and illustrated with examples of yttrium-, titanium-, and oxygen-enriched particles in a mechanically alloyed, oxide-dispersion-strengthened steel.

This article summarizes findings from our previous investigations and recent studies concerning precipitation in a maraging steel of type 13Cr-9Ni-2Mo-2Cu (at.%) with small additions of Ti (1 at.%) and Al (0.7 at.%). The material was investigated after aging at 475°C up to 400 h using both conventional and three-dimensional atom-probe analyses. The process of phase decomposition in the steel proved to be complicated. It consisted of precipitation of several phases with different chemistry. A Cu-rich phase was first to precipitate and Mo was last in the precipitation sequence. The influence of the complex precipitation path on the material properties is discussed. The investigation clearly demonstrated the usefulness of the applied techniques for investigation of nanoscale precipitation. It is also shown that, complementary methods (such as TEM and EFTEM) giving structural and chemical information on a larger scale must be applied to explain the good properties of the steel after prolonged aging.

Mechanical properties, such as hardness and impact toughness, of ferrite-containing stainless steels are greatly affected by long-term aging at intermediate temperatures. It is known that the α-α′ spinodal decomposition occurring in the iron–chromium-based ferrite is responsible for this aging susceptibility. This decomposition can be characterized unambiguously by atom probe analysis, allowing comparison both with the existing theories of spinodal decomposition and the evolution of some mechanical properties. It is then possible to predict the evolution of hardness of industrial components during service, based on the detailed knowledge of the involved aging process.

The influence of W on the temporal evolution of γ′ precipitation toward equilibrium in a model Ni-Al-Cr alloy is investigated by three-dimensional atom-probe (3DAP) microscopy and transmission electron microscopy (TEM). We report on the alloys Ni-10 Al-8.5 Cr (at.%) and Ni-10 Al-8.5 Cr-2 W (at.%), which were aged isothermally in the γ + γ′ two-phase field at 1073 K, for times ranging from 0.25 to 264 h. Spheroidal-shaped γ′ precipitates, 5–15 nm diameter, form during quenching from above the solvus temperature in both alloys at a high number density (∼1023 m−3). As γ′ precipitates grow with aging at 1073 K, a transition from spheriodal- to cuboidal-shaped precipitates is observed in both alloys. The elemental partitioning and spatially resolved concentration profiles across the γ′ precipitates are obtained as a function of aging time from three-dimensional atom-by-atom reconstructions. Proximity histogram concentration profiles (Hellman et al., 2000) of the quaternary alloy demonstrate that W concentration gradients exist in γ′ precipitates in the as-quenched and 0.25-h aging states, which disappear after 1 h of aging. The diffusion coefficient of W in γ′ is estimated to be 6.2 × 10−20 m2 s−1 at 1073 K. The W addition decreases the coarsening rate constant, and leads to stronger partitioning of Al to γ′ and Cr to γ.

It is well established that the response of devices based on the giant magnetoresistance (GMR) effect depends critically on film microstructure, with parameters such as interfacial abruptness, the roughness and waviness of the layers, and grain size being crucial. Such devices have applications in information storage systems, and are therefore of great technological interest as well as being of fundamental scientific interest. The layers must be studied at high spatial resolution if the microstructural parameters are to be characterized with sufficient detail to enable the effects of fabrication conditions on properties to be understood, and the techniques of high resolution electron microscopy, transmission electron microscopy chemical mapping, and atom probe microanalysis are ideally suited. This article describes the application of these techniques to a range of materials including spin valves, spin tunnel junctions, and GMR multilayers.

The first dedicated local electrode atom probes (LEAP [a trademark of Imago Scientific Instruments Corporation]) have been built and tested as commercial prototypes. Several key performance parameters have been markedly improved relative to conventional three-dimensional atom probe (3DAP) designs. The Imago LEAP can operate at a sustained data collection rate of 1 million atoms/minute. This is some 600 times faster than the next fastest atom probe and large images can be collected in less than 1 h that otherwise would take many days. The field of view of the Imago LEAP is about 40 times larger than conventional 3DAPs. This makes it possible to analyze regions that are about 100 nm diameter by 100 nm deep containing on the order of 50 to 100 million atoms with this instrument. Several example applications that illustrate the advantages of the LEAP for materials analysis are presented.

A numerical model has been developed to simulate images obtained from the three-dimensional atom probe. This model was used to simulate the artefacts commonly observed in two-phase materials. This model takes into account the dynamic evolution of the atomic-scale shape of the specimen during field evaporation. This article reviews the model and its applications to some specific cases. Local magnification effects were studied as a function of the size, the shape, and the orientation of precipitated phases embedded in the matrix. Small precipitates produce large aberrations in good agreement with experiments. The magnification from such precipitates, as measured from the simulation, is only found to match the theoretical value for mesoscopic scale precipitates (size similar to the specimen size). Orientation effects are also observed in excellent agreement with experiments. The measured thickness of a grain-boundary-segregated film in the simulation is found to decrease with the angle between the normal to the grain boundary and the tip axis. Depth scaling artefacts caused by variation in the evaporation field of atoms in multilayer structures were successfully simulated and again showed good agreement with effects observed experimentally.

Following is a list of microscopy-related meetings and courses. The editors would greatly appreciate input to this list via the electronic submission form found in the MSA World-Wide Web page at http://www.msa.microscopy.com. We will gladly add hypertext links to the notice on the web and insert a listing of the meeting in the next issue of the Journal. Send comments and questions to JoAn Hudson, hudson@uoneuro.uoregon.edu or Nestor Zaluzec, zaluzec@aaem.amc.anl.gov.

The following shows the correction to Figure 8 that appeared on page 103 of Microscopy and Microanalysis, 10:1, February 2004, in the article by Own et al. The three sections of Figure 8 were previously labeled as a, c, and c. The corrected figure below has the sections correctly labeled as a, b, and c.

The Editor and Cambridge University Press regret the inconvenience that this inadvertent error may have caused.