| Titel: |
Positron annihilation spectroscopy - a non-destructive method for lifetime prediction in the field of dynamical material testing |
| Autor(en): |
K. Bennewitz  , M. Haaks , T. Staab , S. Eisenberg, T. Lampe und K. Maier |
| Journal: |
Zeitschrift für Metallkunde |
| Jahr: |
2002 |
| Band: |
93 |
| Ausgabe: |
8 |
| Seite(n): |
778--783 |
| Zusammenfassung: |
The fatigue behavior of iron-based materials has been investigated by rotating bending testing, employing positron annihilation spectroscopy to probe defects on the atomic level. Positron annihilation spectra have been recorded at various stages of material fatigue. The defect density has been determined by analysing the line shape of the Doppler broadening of the annihilation radiation in the photo peak. The line shape parameter (S parameter), a measure of the defect density, showed a linear relation to the logarithm of the number of loadings, thus from only a small number of loadings it is possible to determine the remaining useful life of the sample. Furthermore, along the longitudinal sample axis spatially resolved line-scans are taken using the Bonn Positron Microprobe. Due to the special sample geometry, the stress gradient allows to obtain the S parameter for different values of the applied load using the very same sample. This leads to a way to determine a complete Wohler diagram using a non-destructive method for just one sample. |
