Development of magnesium-based alloys for elevated temperature applications

In this thesis, the mechanical properties including tensile properties and creep resistance of twelve Mg-Zn-Al (ZA) experimental alloys were evaluated. It was found that the creep resistance of some ZA experimental alloys was significantly higher than that of AZ91, and their tensile properties were comparable to those of AZ91. The evaluation of the effect of calcium and strontium on mechanical properties of ZA alloys was carried out. The results show that calcium and strontium can improve further the creep resistance of ZA alloys at the expense of slight reduced tensile properties. Moreover, in order to understand the strengthening rules of Mg-Zn-Al and Mg-Zn-Al-Ca (ZAC) alloys, and obtain the fundamental knowledge to develop new alloys, the solidification microstructure of some ZA and ZAC experimental alloys was observed, and the solidification behaviors were also studied. Besides, the influence of casting processes (die casting and permanent mould casting) on mechanical properties and microstructure of the magnesium alloys was investigated.