Effect of ECAE conditions on the microstructure, texture and mechanical properties of an extruded Mg-Zn-Y-Zr alloy

Equal channel angular extrusion (ECAE) experiments of an extruded Mg-Zn-Y-Zr alloy with an intense basal texture were performed up to 8 passes at 250 and 350 degrees C through route Bc (billets with a rotation of 90 in the same direction between passes) and route A (without rotation between passes). It was found that under these ECAE conditions significant grain refinement was achieved. The initial texture of the alloy gradually altered as the number of ECAE passes increased. The ductility of the alloy was improved in all the cases after eight passes. The yield strength of the alloy ECAEed through route Bc considerably decreased with the passes increasing, as a result of the formation of the texture component with the basal planes inclined at about 45 to the ECAE direction. The yield strength of the material ECAEed at 250 degrees C with a finer grain structure was considerably lower than that at 350 degrees C with a coarser grain structure. This abnormal phenomenon was attributed to more crystals in the former being oriented to be more favorable for basal slip.