Materials Science and Engineering A-structural Materials Properties Microstructure and Processing | 2019
Effect of Zn content on hot deformation behavior of extruded Mg–Gd–Zn alloys
Abstract
Abstract The effect of Zn content on the hot deformation behavior of Mg–2Gd–xZn (x\u202f=\u202f0, 1, 2 and 3\u202fwt%) alloys was studied by performing shear punch tests (SPT) in the temperature range of 623–723\u202fK and shear strain rate range of 1.0\u202f×\u202f10−2–1.2\u202f×\u202f10−1 s−1. Arrhenius-type constitutive equations were employed to investigate the hot deformation behavior. It was found that addition of 1\u202fwt% Zn yields the highest shear strength due to imposing higher solute drag pressure resulted from the co-segregation of Gd and Zn at grain boundaries and dislocations. Stress exponents of 2.7–5.5 and activation energies of 171–228\u202fkJ\u202fmol−1 indicated that the main deformation mechanism is dislocation viscous glide with some contributions of dislocation climb and grain boundary sliding in various alloys. Finally, the optimum processing condition having the highest power dissipation efficiency was determined by developing processing maps. The microstructures of the safe and unsafe regions were associated with complete and partial dynamic recrystallization, respectively.