Enhanced strength and ductility of Mg-RE-Zn alloy simultaneously by trace Ag addition

The effects of Ag on the microstructure and mechanical properties of a Mg-9Gd-3Y-1Zn-0.8Mn alloy have been investigated. Microstructural analysis indicates that the (Mg,Zn)3(Gd,Y)-type eutectic phase in the as-cast alloys transform into LPSO phase during solution treatment. The presence of Ag atom facilitates the formation of lamellar LPSO phase in the grain, which restrains recrystallization behavior during extrusion. The formation of β′ and γ′ phases can be remarkably promoted by Ag addition during aging treatment. The co-precipitation of β′ and γ′ phases generates an approximate enclosed microstructure which endows the alloy with ultra-high strength and favorable ductility.