Effect of LPSO orientation on the compression behavior and workability of the Mg-5Gd-3Y–1Zn-0.5Zr alloy

Abstract

To investigate the effect of LPSO orientation on the compression behavior and workability of Mg alloys, a Mg-5.3Gd-3.3Y-1.1Zn-0.5Zr (wt%) alloy was extruded to obtain the bimodal microstructure with a certain amount of directionally arranged LPSO phases. The subsequent compression tests indicate that the values of activation energy of deformation (Q) are approaching (180–194 kJ/mol) along different orientations (ED, 45°, and TD), which are much lower compared with the as-homogenized Mg-Gd-Y-Zn-Zr alloys due to the sufficient initial grain boundaries (I-GBs). Enhanced kinking and DRX at kink bands at the higher Zener-Hollomon (Z) parameters result in the slight decrease of Q and the movement of optimal processing domains for the ED orientation. The I-GBs overshadow the effect of LPSO orientation via kinking deformation on the DRX ratio and workability. The increase of Z parameter tends to reduce the DRXed grain size and the homogeneity of both the microstructure and hardness. Different α-Mg and LPSO orientations of the extruded alloy induce the anisotropy of peak flow stress (σp) during compression and the extraordinary elliptical shape of the compressed TD specimens. This work provides useful information for the industrial production of wrought LPSO-containing Mg alloys.