Room-temperature ductility and anisotropy of two rolled Mg-Zn-Gd alloys

To develop new magnesium alloy sheets with high formability at room temperature, the microstructure, texture, ductility and anisotropy of rolled EMg-1%Zn-1%Gd and Mg-2%Zn-1%Gd sheets were investigated. The microstructures were characterized as fully recrystallized grains with a large amount of homogeneously distributed fine particles in the matrix. The sheets exhibit an excellent ultimate elongation of nearly 36% and an uniform elongation greater than 15%. The Mg-1%Zn-1%Gd sheet has a random basal texture and the basal pole is tilted by about 30 from the normal direction towards the transverse direction. The planar anisotropy is shown to be as low as 0. The flow curves of the two Mg-Zn-Gd alloys display an abrupt yielding with a remarkable linear hardening at high strain rate after a plastic strain of roughly 3%. The majority of grains in the tilted texture have an orientation favorable for both basal slip and tensile twining because of a high Schmid factor. The low planar anisotropy, the large uniform elongations and the high strain-hardening rate observed in the Mg-Zn-Gd sheets imply excellent room temperature formability. (C) 2010 Elsevier B.V. All rights reserved.