Abstract
A newly developed Mg-2Gd-0.5Zr-xZn (x = 0.5, 1.0, 2.0, 3.0 wt %) alloy system exhibits significant strengthening by doping with Zn. In order to understand the strengthening mechanism, the microstructure, texture evolution, and mechanical properties of ultrahigh ductility Mg-2Gd-0.5Zr alloys with a Zn addition were systematically investigated. The addition of Zn results in the formation of Mg-Gd-Zn intermetallic compounds along grain boundaries, which encourages grain refinement during hot extrusion via the particle stimulated nucleation (PSN) mechanism. Furthermore, during texture sharpening the pole changes from <201> to <010>, which also occurred in the extruded alloys with Zn addition, which is unfavorable for the basal slip and tensile twinning. Mg-2Gd-0.5Zr-3Zn shows well-balanced strength and ductility with a tensile yield strength (YS) and ultimate tensile strength (UTS) of 285 and 314 MPa, accompanied by a high tensile elongation of 24%. They are superior to those of commercial AZ31. The enhanced strength is attributed to grain refinement, precipitation strengthening, and texture sharpening induced by alloying with Zn. The research result is also of great value to the development of low rare-earth, high strength, and high room temperature ductility magnesium alloy.
Highlights
Magnesium (Mg) alloys are the lightest metallic structural materials, compared to aluminum, titanium, and steel [1]
The enhanced strength is attributed to grain refinement, precipitation strengthening, and texture sharpening induced by alloying with Zn
A great deal of research has been devoted to improving the room temperature ductility or strength of Mg alloys by alloying, heat treatment, and severe plastic deformation (SPD) [8,9,10,11]
Summary
Magnesium (Mg) alloys are the lightest metallic structural materials, compared to aluminum, titanium, and steel [1]. With the advantages of low density, high specific strength, good damping capacity, and abundant resources, Mg alloys have attracted considerable attention in an automotive industry responding to energy saving and lightweight strategy [2,3,4,5,6,7]. The poor room temperature ductility and limited strength of Mg alloys have retarded their wider application severely. A great deal of research has been devoted to improving the room temperature ductility or strength of Mg alloys by alloying, heat treatment, and severe plastic deformation (SPD) [8,9,10,11]. It is difficult to obtain high strength with excellent ductility simultaneously. Developing well-balanced strength and ductility Mg alloys is a critical strategy for further extending the potential usage of Mg alloys
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