FABRICATION AND PROPERTIES OF RAPIDLY SOLIDIFIED MAGNESIUM AND MG-SI ALLOYS

Extruded rods have been produced from gas atomised powders of pure magnesium and a magnesium alloy containing 2 wt-%Si. It has been found that the microstructures of the powders vary with the powder size. The static mechanical properties at ambient temperature show significant improvement compared with their ingot equivalent. The tensile properties of both materials increase with increase in the extrusion temperature, even though the refinement in the microstructure in terms of average grain size is more pronounced at lower temperatures. This is shown to result from the retention of porosity in the low temperature extrudates. The nature of pore formation has been explained on the basis of the parent powder characteristics and the extrusion parameters. The mechanical properties of the alloys produced are stable after exposure to high temperature for short periods but the high temperature mechanical properties do not show any significant improvement. The extrudates have a recrystallised grain structure and develop a texture equivalent to that of conventionally extruded materials. © 1990 The Institute of Metals.