Alloy development requires investing huge efforts in the selection of the alloying elements and in the determination of potential compositions and their heat treatments. This effort can be reduced by "intelligent" selection of alloys and processing based on thermodynamic considerations. As an example, we would like to report on the design of heat-treatable Al-free Mg-based alloys, their heat treatment and on the expected precipitation phases during aging following solution treatment as well as exposure to elevated temperatures without precedent heat treatment. The thermodynamically predicted phase formation will be compared with experimental results. (c) 2006 Springer Science + Business Media, Inc.