Effect of Zn addition on mechanical and corrosion properties of as-cast and as-extruded WE43 magnesium alloys

Abstract

In this study, the microstructure, mechanical properties and corrosion resistance of as-cast and as-extruded WE43-xZn (x = 0, 0.5, 1.0 wt%) magnesium alloys were investigated. The microstructure of the as-cast alloys showed that the WE43-xZn alloys contained Mg41Nd5 and Mg24Y5 intermetallic compounds. Besides, LPSO (Long-period stacking ordered) type Zn-rich phases were also originated in the microstructure with increasing Zn content. Furthermore, LPSO structure was observed both in the α-Mg grain and at the grain boundaries in Zn-containing WE43 alloys. The Vickers hardness values increased by the raising Zn content in the as-cast, solution treated and as-extruded WE43-xZn alloys. It was observed that yield strength (YS) increased gradually by the addition of Zn content, but 0.5 wt% Zn addition to as-cast WE43 alloy resulted in much more improvements on the ultimate tensile strength (UTS) and elongation % (EL) values compared to as-cast WE43-1.0Zn alloy. It was seen that mechanical properties improved with increasing Zn content for the as-extruded alloys. The as-cast specimens showed that corrosion resistance improved by increasing Zn content due to the presence of LPSO structures, but in the extruded alloys it varied in relation to the presence and distribution of second phases and also the morfologies of LPSO structures.