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M: Metallphysik

M 14: Postersitzung

M 14.5: Poster

Thursday, March 30, 2000, 15:00–19:00, C

Thermal characterization of thermally and mechanically cycled NiTi shape memory alloy samples by photothermal methods — •Dirk Dietzel¹, M. Kaack¹, D. Wurzel², I. Delgadillo¹, J. Gibkes¹, B.K. Bein¹, E. Hornbogen², and J. Pelzl¹ — ¹Experimentalphysik III, Ruhr-Universität Bochum, 44780 Bochum, Germany — ²Institut für Werkstoffe, Ruhr-Universität Bochum, 44780 Bochum, Germany

Photothermal methods based on IR radiometry, photopyroelectric detection and thermoreflectance have been applied to NiTi shape memory alloys to characterise the thermal properties of the as- prepared samples and to determine the changes of the thermal properties induced by thermal and mechanical treatment and cycling. Using photopyroelectric detection the integral diffusivities of the treated and nontreated specimens have been determined. Depth profiles of the thermal properties of the mechanically and thermally cycled ribbon samples were measured using photothermal radiometry. A photothermal microscope based on the thermal reflectance was applied to monitor the thermal diffusivity accross the ribbon edge indicating considerable modifications of the thermal properties near the surface in agreement with the depth profiles obtained by photothermal radiometry. Using the photothermal microscope also the thermal and optical variations could be imaged on microscale inside a grove which was produced by a micro-miller on a NiTi shape memory specimen.