Enhanced precipitation-hardening in Mg–Gd alloys containing Ag and Zn

The maximum hardness achievable in Mg–6 wt.%Gd–0.6 wt.%Zr alloy during isothermal aging at 200 and 250 °C can be increased substantially by controlled additions of Ag or Zn. A further increase in the maximum hardness can be achieved when Ag and Zn are added together. The remarkable improvement in precipitation-hardening in the resultant alloys is associated with a dense distribution of nano-scale basal precipitate plates.