Title: |
Material Science with Positrons: From Doppler Spectroscopy to Failure Prediction |
Author(s): |
M. Haaks , P. Eich , J. Fingerhuth and I. Müller |
Journal: |
Advances in Solid State Physics |
Editor: |
Rolf Haug |
Year: |
2008 |
Volume: |
47 |
Series: |
Advances in Solid State Physics |
Pages: |
289-300 |
Publisher: |
Springer Berlin / Heidelberg |
Affiliation: |
Helmholtz Institut für Strahlen- und Kernphysik, Universität Bonn, Nußallee 14-16, 53115 Bonn, Germany |
DOI: |
10.1007/978-3-540-74325-5_23 |
ISBN: |
978-3-540-74324-8 |
File URL: |
http://www.springerlink.com/content/k4lx118586wl3227/ |
Abstract: |
We describe an alternative approach for a reliable lifetime prediction employing the local concentration of lattice defects as a precursor for fatigue failure. We present positron annihilation spectroscopy (PAS) as a non-destructive technique sensitive for defect concentrations in the range relevant to plasticity in metals. The Bonn Positron Microprobe (BPM), a currently unique device, provides a fine focused positron beam with a selectable beam diameter from 5 to 200 µm assisted by an inbuilt fully functional scanning electron microscope (SEM). Using the BPM, plasticity and fatigue can be measured with a lateral resolution from some microns up to the range of millimeters. Employing laterally resolved PAS and the empirical supposition of a linear relation between the defect concentration and the logarithm of the number of fatigue cycles, the point of failure was successfully predicted on the common carbon steel AISI 1045. For a generalization of the precursor method, a minimal model of fatigue based on a cellular automaton was developed. First results from a one-dimensional implementation are presented. |