Dresden 2006 – scientific programme

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MM: Metall- und Materialphysik

MM 7: Symposium Severe Plastic Deformation II

MM 7.2: Talk

Monday, March 27, 2006, 15:15–15:30, IFW A

Vacancy type defects in severely plastically deformed Ni — •Erhard Schafler, Gerd Steiner, Elena Korznikova, Heinrich Schindler, Michael Kerber, and Michael Zehetbauer — Institut für Materialphysik, Universität Wien, Boltzmanngasse 5, A-1090 Wien

Ni of two different purities have been deformed to different strains by high pressure torsion at room temperature using two different hydrostatic pressures. For comparison, some investigations by conventional deformation (rolling, compression) have been carried out, too. The material has been investigated by X-ray diffraction Bragg profile analysis, differential scanning calorimetry as well as residual electrical resistivity. The X-ray method gives information about the dislocation density and their arrangement, and the size and distribution of the smallest structural elements (coherently scattering domains). While the X-ray method detects the dislocations solely, the two other (annealing) methods are sensitive to both vacancies and dislocations. Therefore the proper combination of the results enables to analyse and quantify the evolution of vacancy type defects [1]. Similarly as in the case of Cu, the vacancy concentrations induced by SPD processing are definitely higher than those from conventional plastic deformation [2]. The resulting concentrations of vacancies are discussed in view of their dependencies on the deformation strain, the hydrostatic pressure and the purity of the material used.

[1] M. Zehetbauer, E. Schafler, T. Ungar, Z. Metallk., Vol 96(9) (2005) 1044-1048 [2] E.Schafler, G.Steiner, E.Korznikova, M.Zehetbauer, Mater.Sci Eng. A,410-411, (2005) 169-173.