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M: Metallphysik

M 22: Mechanische Eigenschaften III

M 22.5: Vortrag

Dienstag, 25. März 2003, 15:45–16:00, IFW B

Slip and deformation twinning in laser shock loaded molydenum single crystals — •Joerg Kaspar¹, Arnhold Luft¹, and Werner Skrotzki² — ¹Fraunhofer-Institut fuer Werkstoff- und Strahltechnik, Winterbergstrasse 28, 01277 Dresden — ²Institut f*r Kristallographie und Festkoerperphysik, Technische Universitaet Dresden, 01062 Dresden

Slip and twinning are two fundamental modes by which metals and alloys can deform plastically. Whenever the applied conditions make it difficult for the material to deform by slip alone, twinning and slip take place concurrently. On lowering the deformation temperature, the transition from slip to slip and twinning occurs in many bcc metals and alloys. However no deformation twins have been found during deformation at low strain rates in molybdenum single crystals even at temperatures as low as 1.85 K. On the other hand at very high rates of deformation, which are experienced during laser shock processing, twinning is also observed in molybdenum. The present work deals with the deformation behaviour and the microstructural processes taking place within laser shock loaded molybdenum single crystals. It is shown by means of different complementary investigation methods (LM, SEM, TEM) how different processing parameters (number of laser impacts, laser pulse energy) influence the choice of activated deformation modes and the microstructural evolution. Based on the results conclusions are drawn regarding the formation and growth mechanism of deformation twins in molybdenum during deformation at high strain rates.