Sammendrag
The Al-Mg-Si (6xxx-series) alloy system is a precipitation hardened alloy gaining much ofits strength from precipitate phases acting as pinning centers for dislocation movement. Fiveyears ago, Zandbergen, Andersen and coworkers identified the crystallography of the so-calledβ'' phase, one of the main hardening phases, using solely electron microscopy techniques [1].Later, several other phases have been identified using high resolution microscopy. To solve thecrystallography of these phases and to get an increased understanding of the electronic structureand bonding, ab initio modeling has proven to be a valuable tool. We present results fromcalculations on two recently discovered phases and show how ab initio modeling can give insightinto the bonding trends and electronic structure of the phases in this alloy system. 1. H. W. Zandbergen, S. J. Andersen and J. Jansen, Science 277, 1221 (1997)