Atom Probe Tomography: Analysis at the Atomic Level

Written by the inventor of the technique, this book provides the first complete description of atom probe tomography (APT). This microanalytical technique enables the distribution of all the elements present in a material to be experimentally determined. The instrument known as a three-dimensional atom probe (3DAP) is able to determine the spatial coordinates and the elemental identities of the individual atoms in a metal with atomic resolution. The compositions of small volumes are determined by simply counting the number of atoms of each type within that volume, and thus the technique provides a fundamental measure of the local concentration. The book provides a brief history of the development of the APT technique and the different types of three-dimensional atom probes that have been developed. The various methods of fabricating the needle-shaped specimens and the procedures used to obtain high resolution images of the specimen with field ion microscopy and to conduct a three-dimensional atom probe analysis are described in detail. Special attention is given to the selection of the experimental parameters required to provide accurate analyses. The methods of visualizing and analyzing the three-dimensional data are described. The technique has been used to characterize the microstructures of a wide spectrum of metals ranging from simple model systems to complex commercial alloys. A comprehensive list of papers relating to the metallurgical applications of atom probe tomography is included.

Table of Contents:
1 Overview and Historical Evolution.- 1.1 General Introduction.- 1.2 Evolution of the Three-dimensional Atom Probe.- 2 The Art of Specimen Preparation.- 2.1 Initial Preparation Methods.- 2.2 Thin Films.- 2.3 Electropolishing.- 2.4 Milling.- 2.5 Other Methods.- 2.6 Cleaning and Inspection.- 2.7 Prescreening in Transmission Electron Microscope.- 3 Field Ion Microscopy.- 3.1 Imaging Procedure.- 3.2 Field Ion Micrographs.- 3.3 Estimation of Parameters from Field Ion Images.- 3.4 Theoretical Background of Field Ion Microscopy.- 4 Instrumentation.- 4.1 Vacuum System.- 4.2 Field Ion Microscope.- 4.3 Mass Spectrometer.- 4.4 Instruments.- 5 Experimental Factors.- 5.1 Atom Probe Analysis Procedure.- 5.2 Volume of Analysis and Geometrical Considerations.- 5.3 Preferential Retention and Evaporation.- 5.4 Interpretation and Assignment of Ions.- 5.5 Reconstruction of Atom Positions.- 5.6 Detection Efficiency.- 5.7 Specimen Rupture or Failure.- 6 Data Representations and Analysis.- 6.1 Visualization and Analysis Methods for Individual Atoms.- 6.2. Smoothing Data.- 6.3 Data Representations.- 6.4 Composition Determinations.- 6.5 Estimation of Dimensions.- 6.6 Clustering and Ordering.- 6.7 Topological and Fractal Methods.- A. Reviews.- B. Phase Transformations.- C. Steels.- D. Superalloys.- E. Intermetallics.- F. Aluminum Alloys.- G. Multilayers and Films.- H. Miscellaneous Studies.- I. Other Sources of Reference to Atom Probe Studies.- Appendices.- A Formulae.- B Useful Constants and Conversions.- C Predictions of the Low Temperature Evaporation Field and Charge States for the Elements.- D Stereographic Projections.- E Percentage Points of the X2 Distribution.- F Periodic Table of Material Parameters.- G Periodic Table of Isotope Abundances.- Atom Probe Tomography.- Analysis at the Atomic Level.