1. Institute for Materials Engineering; University of Kassel; Moenchebergstrasse 3 D-34109 Kassel Germany
2. now with V & M DEUTSCHLAND GmbH; Boiler & Line Pipe Competence Center; Rather Kreuzweg 106 D-40472 Düsseldorf Germany
3. Department of Physics and CINSaT; University of Kassel; Heinrich-Plett-Strasse 40 D-34109 Kassel Germany
4. now with Carl von Ossietzky University of Oldenburg; Department of Physics; Carl-von-Ossietzky-Strasse 9-11 D-26129 Oldenburg Germany