Microstructures and Mechanical Properties of Extruded High-Purity Magnesium

The microstructure and mechanical properties of the high-purity magnesium (99.99wt.% Mg) extruded by single direct extrusion experiment were investigated. For the extrusion speed of 0.2mm/s, the microstructure of extruded Mg rods was composed of equiaxed fine dynamical recrystallized (DRXed) grains and some elongated coarse un-DRXed grains. The yield strength (YS) and the elongation of the extruded bars were 105.3MPa and 46.7% respectively. In the case of extrusion speed of 4.0mm/s, the DRXed grains were remarkably coarsened and the elongated coarse un-DRXed grains vanished, meanwhile lots of twins occurred and the intensity of basal-plane texture increased a little. With the extrusion speed being raised from 0.2mm/s to 4.0mm/s, the YS and the elongation decreased to 60.5MPa and 22.1% respectively, but the ultimate tensile strength (UTS) was improved from 154.7MPa to 178.8MPa.