The origin of “rare earth” texture development in extruded Mg-based alloys and its effect on tensile ductility

The extrusion behaviour, texture and tensile ductility of five binary Mg-based alloys have been examined and compared to pure Mg. The five alloying additions examined were Al, Sn, Ca, La and Gd. When these alloys are compared at equivalent grain size, the La- and Gd-containing alloys show the best ductilities. This has been attributed to a weaker extrusion texture. These two alloying additions, La and Gd, were found to also produce a new texture peak with 〈 1   1   2 ¯   1 〉 parallel to the extrusion direction. This “rare earth texture” component was found to be suppressed at high extrusion temperatures. It is proposed that the 〈 1   1   2 ¯   1 〉 texture component arises from oriented nucleation at shear bands.