Influence of Zn addition on the microstructure, tensile properties and work-hardening behavior of Mg-1Gd alloy

Abstract

Microstructures, tensile properties and work-hardening behavior of extruded Mg-1Gd-xZn (x = 0, 0.5, 1.0, 1.5, wt.%) alloy sheets were investigated in the present work. All the extruded sheets exhibit a fully-recrystallized microstructure and a weak extrusion-direction (ED)-split texture. The average grain sizes of Mg-1Gd sheets slightly decrease with the increase of Zn content up to 1.0 wt%, while a sharp decrease of the grain size occurs in Mg-1Gd-1.5Zn sheet attributed to the existence of abundant fine W-phase precipitates. Zn addition is found to cause a weak ED-split texture and to gradually form new transverse direction (TD)-split texture component. The combination of Zn solute, fine W-phase precipitate and weakening texture induced by Zn addition simultaneously improve the strengths and ductility of Mg-1Gd-xZn sheets. However, excessive Zn addition leads to larger Mg5Gd precipitates and thus decreases the ductility. With the increment of Zn content from 0 to 1.5 wt%, work-hardening exponents of Mg-1Gd-xZn sheets gradually increase from 0.34 to 0.39 along ED, and from 0.23 to 0.29 along TD, respectively. Meanwhile, hardening capacities increase from 1.73 to 1.84 along ED, and from 0.73 to 1.07 along TD, respectively.