Dresden 2011 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 37: Nanomaterials II

MM 37.7: Talk

Thursday, March 17, 2011, 15:30–15:45, IFW B

Molecular dynamics study of diffusion-induced recrystallisation — •Sebastian Manuel Eich, Michael Kasprzak, and Guido Schmitz — Institute of Material Physics, University of Muenster, Germany

Diffusion-induced recrystallisation (DIR) was investigated in thin film Au-Cu and Ni-Pd interdiffusion couples. Characteristic concentration levels are observed inside newly formed grains instead of the expected continuous Ficks diffusion profiles. This effect seems to be related to elastic mismatch strain in the diffusion zone. Experimental results reveal a relationship between characteristic compositions and the ideal shear strength of metals. Within the diffusion zone, the characteristic compositions are always adjusted so that a maximum stress of about 70% of the ideal shear strength is established. In our model, we use molecular dynamics based on embedded-atom potentials (EAM) to study the process of DIR in gold-copper diffusion couples. We simulate the stress development in thin (3-6 nm) copper layers fixed to a substrate. Step by step, copper atoms are replaced by gold. We observe a linear increase in stress with gold concentration until a critical level is reached and spontaneous relaxation and break of coherency take place. Using different conditions (temperature, external pressure ...), we are able to confirm that the maximum stress is close to, but always lower than the ideal shear strength in the dominant slip system.