MICROSTRUCTURE OF A PRESSURE DIE CAST MAGNESIUM-4WT.PERCENT ALUMINUM-ALLOY MODIFIED WITH RARE-EARTH ADDITIONS

Addition of cerium-rich mixtures of rare earth (RE) elements to alumin ium-containing magnesium pressure die cast alloys is known to improve the creep properties at elevated temperatures. In the present investig ation, a detailed description of the microstructure of a magnesium-4 w t.%, aluminium alloy containing 1.4 wt.%, of a cerium-rich mixture of RE elements is presented. Particle types occurring and their distribut ion in the microstructure, as well as the distribution of elements in solid solution, are described. Heat treatment is carried out to verify if solid state precipitation occurs. Some qualitative arguments for t he beneficial effect of RE elements on the creep properties are presen ted.