Dresden 2006 – wissenschaftliches Programm
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MM: Metall- und Materialphysik
MM 44: Mechanical Properties II
MM 44.3: Vortrag
Freitag, 31. März 2006, 11:30–11:45, IFW A
X-rays and Positrons Compared: Plasticity Studies on Deformed Carbon Steel — •Matz Haaks1, Stephan Roth2, and Karl Maier1 — 1Helmholtz-Institut für Strahlen und Kernphysik, Nußallee 14-16, 53115 Bonn — 2Hasylab/Desy, Notkestraße 85, 22607 Hamburg
Plastic deformation is based on the movement and multiplication of dislocations, leading to jumps out of the glide plane. The movement of these jogged dislocations is always accompanied by the production of vacancies. In X-ray diffraction pattern the presence of dislocations causes a broadening of the diffraction reflexes. Using a high energy X-ray source with sufficient luminosity, powder-like Debye-Scherrer conditions can be achieved in a polycrystalline carbon steel with optimized geometry by diffracting in a volume containing 20000 grains. Positron Annihilation Spectroscopy (PAS) is used as a complementary method. It is non-destructive and highly sensitive for the detection of the vacancies associated with the dislocations.
We analyzed samples deformed in a three-point bending test with scanning X-ray diffraction in transmission at the high-energy beam line at Petra II/Hasylab as well as with scanning positron microscopy at the Bonn Positron Microprobe. The results from both methods are presented and compared.
As a practical application of transmission X-ray diffraction, the fabrication method of a historical cannon was investigated. We were able to decide between casting and forging.