Dresden 2011 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 34: Nanomaterials I
MM 34.2: Vortrag
Donnerstag, 17. März 2011, 11:15–11:30, IFW B
In Situ Probing of fast Defect Annealing in Cu and Ni with a High-Intensity Positron Beam — •Bernd Oberdorfer1, Eva-Maria Steyskal1, Wolfgang Sprengel1, Werner Puff1, Philip Pikart2, Christoph Hugenschmidt2, Michael Zehetbauer3, Reinhard Pippan4, and Roland Würschum1 — 1Inst. f. Materialphysik, TU Graz (A) — 2Physik Dept. E21 u. FRM II, TU München (D) — 3Physik Nanostr. Mater., Fak. Physik, Univ.Wien (A) — 4Erich Schmid Inst. Mater. Sci, Univ. Leoben (A)
The thermally activated annealing characteristics of atomic defects in ultrafine-grained, high purity Ni and Cu after severe plastic deformation (SPD) have been analyzed by means of positron annihilation techniques and dilatometry. This was realized using the high-intensity monoenergetic positron beam at the NEPOMUC positron source of FRM II which allows for fast, in situ temperature dependent positron-electron annihilation spectroscopy on a time scale of minutes. Furthermore, high-precision length change measurements with a difference dilatometer provided information about the amount of excess free volume in these SPD materials associated with defects such as vacancies, vacancy agglomerates, dislocations and grain boundaries. The combination of these two in situ methods, atomistic positron annihilation and macroscopic dilatometry allows for an identification of the structural defects in solids by means of a detailed analysis of their annealing kinetics upon linear heating [1]. Financial support by the Austrian Science Fund (FWF) is appreciated (project P21009-N20).
[1] B. Oberdorfer et al., Phys. Rev. Lett. 105, 146101 (2010).