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M: Metallphysik

M 13: Grenzfl
ächen

M 13.2: Fachvortrag

Dienstag, 12. März 2002, 16:45–17:00, H4

Molecular Dynamics Simulations of Grain Boundary Migration in Tungsten — •Ramachandran Sankarasubramanian¹, Bernd Eberhard^1,2, and Ferdinand Haider¹ — ¹Universität Augsburg, Universitätstr. 1, 86135, Augsburg — ²OSRAM GmbH, Mittelsletter Weg 2, 86830, Schwabmünchen

Grain boundaries in tungsten act as shortcut diffusion path for impurities which lower the workfunction at the surface. In our molecular dynamics simulations, we take a cylindrical grain embedded within another grain with Σ5, boundary orientation. We use embedded atom potential and perform the MD simulations in the temperature range 1500-3500 K, up to 200 ps, and measure the position of the grain boundary as a function of time. The curvature of the grain boundary acts as the driving force for its motion. Our preliminary results indicate that the activation energy for grain boundary migration is approximately, 1 eV, which is lower than the experimentally measured activation energy for self-diffusion in tungsten (1.63 eV). We are also studying the effect of a foriegn atom on the mobility of the grain boundary.