Mechanical anisotropy of extruded Mg-6% Al-1% Zn alloy

Deformation anisotropy of extruded Mg-6% Al-1% Zn alloy has been investigated on specimens with different tilt angles relative to the extrusion direction. Calculations of the orientation factors for basal slip and of the strains caused by {10 (1) over bar2} twinning were done for a slightly idealised texture. This quantification of the two dominating deformation modes was used to explain the marked mechanical anisotropy of the extruded magnesium alloy. Basal slip as well as 11012} twinning is inhibited in extrusion direction under tensile loads, which results in high yield strength. Any other testing direction and/or compressive loads are capable of activating slip and/or twinning and yield stress is significantly lower under such conditions. The lattice reorientation of 86.3 caused by twinning has a large influence on the deformation behaviour of a pre-deformed specimen, since the twinned areas are capable of untwinning during reloading in the opposite direction. (C) 2004 Elsevier B.V. All rights reserved.