On the role of yttrium in microstructure evolution and texture modification during magnesium alloy extrusion

Three binary alloys, Mg-1wt%Al, Mg-1wt%Y, and Mg-4wt%Y were forward extruded to investigate the effect of the yttrium addition on the evolution of texture and microstructure of magnesium alloys during extrusion. The non-rare earth (RE) alloy Mg-1wt%Al exhibits a 101¯0 or 101¯0−112¯0 fiber texture depending on the recrystallized fraction, whereas the RE alloys Mg-1wt%Y, and Mg-4wt%Y develop weaker texture and a new 112¯1 “RE texture” component. The microstructure was characterized by using the electronic backscattered diffraction (EBSD) technique, and the formation mechanism of “RE texture” component was probed. The enhanced twin activity in the RE alloys leads to the broadened orientation spread of grains, but is little related to the formation of the “RE texture” component. Further examination on the dynamically recrystallized (DRX) grains reveals that both 112¯0 and 112¯1 texture components are closely related to the continuous dynamic recrystallization (CDRX) during which new grains nucleates in the mantle regions of the original grains.