Place: MMM 2012 - 6th International Conference on Multiscale Materials Modeling, Biopolis, Singapore
Continuum modelling of polycrystals requires knowledge of the elastic and plastic properties of the interfaces in their microstructure. To capture the physics of grain boundary sliding, migration, and decohesion, these processes should be investigated by atomistic calculations. A quantum mechanical treatment is necessary especially if the influence of segregated impurities, which can alter the bond character, shall also be described. However, the construction of continuum constitutive laws for grain boundaries from the results of ab-initio calculations still requires sampling a five parameter space: the orientation of the grain boundary plane, the misorientation axis and the misorientation angle. This remains a formidable task, even with today's computers. In this presentation we will introduce our investigation of the mechanical properties of grain boundaries in aluminum, which aims at replacing such a comprehensive sampling by as few representative calculations as possible. For this we are evaluating a “design of experiment scheme” combined with the insight on the role of crystallography that we gain from our ab-initio calculations: On the one hand we are investigating discriminating features in the elastic and plastic response of tilt and twist grain boundaries. On the other hand we are looking for common behaviour that enables a unified treatment and a separation of variables.