Tensile flow and strain-hardening behaviors of dual-phase Mg-Li-Zn alloy thin sheets

The tensile flow behavior and associated microstructure changes of the cold-rolled Mg-Li-Zn alloys with a thickness of 0.6 mm containing approximately 6 and 9 wt% of Li were examined under tension. Tensile tests were carried out on specimens in the directions of 0 degrees, 45 degrees and 90 degrees to the rolling direction using an initial strain rate of 1.67 x 10(-3) s(-1) at room temperature. Kocks-Mecking type plots were constructed to illustrate different stages of strain-hardening. The results showed that tensile properties could be related to the deformed microstructures. Analysis of the flow behavior and the deformed microstructures indicated that the mechanical properties were related to the deformation of BCC beta-phase in the cold-rolled Mg-6Li-1Zn (designated as 1261) alloy sheet. The beta-phase did not show significant deformation in the 90 degrees specimens, leading to a higher strength and a higher stage II strain-hardening rate in this direction in the 1261 alloy sheet. The activity of non-basal slips resulted in the considerable deformation of the alpha-phase in all test directions in the cold-rolled Mg-9Li-1Zn (designated as 1291) alloy sheet. (C) 2010 Elsevier B.V. All rights reserved.