| Numéro |
J. Phys. Colloques
Volume 50, Numéro C8, Novembre 1989
36th International Field Emission Symposium
|
|
|---|---|---|
| Page(s) | C8-535 - C8-540 | |
| DOI | https://doi.org/10.1051/jphyscol:1989892 | |
J. Phys. Colloques 50 (1989) C8-535-C8-540
DOI: 10.1051/jphyscol:1989892
SOME ASPECTS OF THE MEASUREMENT OF COMPOSITION IN THE ATOM PROBE
M.G. HETHERINGTON1 et M.K. MILLER21 Department of Metallurgy and Science of Materials, Oxford University, GB-Oxford OX1 3PH, Great-Britain
2 Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6376, U.S.A.
Abstract
The measurement of compositions in the atom probe has been studied by considering the phase decomposition of high purity Fe-Cr alloys. Alloys containing 45% Cr were aged for up to 500h at 500°C in order to study the early stages of the decomposition. Typical data representations are considered as fractals. The scaling exponents have been measured for different aging conditions and three different scaling regimes have been identified. The consequences of the fractal nature of the profile are discussed. The results indicate that there is an optimum block size at which the composition and other physical parameters may be reliably measured. The cumulative plot is shown to be a fractional Brownian motion suggesting that the simulation of the microstructures by randomly placed spheres is not consistent with the observed microstructures.