High hardness in a nanocrystalline Mg97Y2Zn1 alloy

► Synthesis of nc (21 nm) Mg97Y2Zn1 alloy using a modified mechanical alloying. ► Annealing at 573 K increases the grain size to 28 nm with a hardness of 2.4 GPa. ► This is the highest value for hardness yet reported for a Mg-base (>95% Mg) alloy. ► The excellent strength of this alloy is discussed throughout the article.