Enhanced age-hardening and formation of plate precipitates in Mg–Gd–Ag alloys

The addition of 0.25–0.5 at.% of Ag to Mg–3.4Gd–0.1Zr (at.%) alloy significantly enhances the age-hardening response, particularly in underaged conditions. The peak-aged Mg–3.4Gd–0.5Ag–0.1Zr alloy exhibits an extremely high ultimate strength, of above 410 MPa. The plate precipitates are formed on the basal plane of the matrix with a high number density in underaged conditions and co-exist with β′ phase in the peak-aged condition. The co-precipitation effectively contributes to the strengthening of the alloy. In the Ag-added Mg–Gd alloys, characteristic initial structure change is found.