Dresden 2009 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 35: Poster Session II

MM 35.27: Poster

Mittwoch, 25. März 2009, 16:30–18:30, P4

Mechanical properties of LiB₃O₃ at nanoscale — •Irina P. Shakhverdova¹, Peter Paufler¹, Rimma S. Bubnova2², Stanislav K. Filatov³, and Dirk C. Meyer¹ — ¹Institut für Strukturphysik, TU Dresden, 01062 Dresden, Germany — ²Institute of Silicate Chem., Russian Academy of Sciences, Ul. Odoevvskogo, 24/2, St.Petersburg 199155, Russia — ³Dept. of Crystallography, St.Petersburg State University, Univ.Emb.7/9, St.Petersburg 199034, Russia

Indentation hardness (H), scratch hardness (H_S) and reduced Young’s modulus (E_r) of LiB3O5 single crystal plates with different orientation as well as of glass with the same composition have been investigated using nanoprobes. Microhardness (H_M) tests were done for comparison. Both hardness and Young’s modulus of glass appeared smaller compared to corresponding single crystal data (H∼7–8 GPa, H_M∼ 6 GPa, E_r∼ 70–80 GPa for glass and H∼ 10–15 GPa, H_M∼ 6–11 GPa, E_r∼ 93–155 GPa for single crystal). H, H_S, E_r and the plane of crack propagation proved orientation-dependent. Cracks in the glass sample were not observed up to 0.49 N microindentation load, whereas for the single crystal the cracks appeared already at 0.098 N. In single crystals the observed cleavage planes {211} and/or {412} are oriented nearly parallel to planes of B-O rings. The dependence of scratch morphology on the direction of scratching is demonstrated quantitatively. The coefficient of friction depends on normal load and varies between 0.25 and 0.37. The oscillating friction reflects elementary processes of plastic deformation at nanoscale. Dislocations created during scratching have been detected by etching.