Deformation twinning in a nanocrystalline hcp Mg alloy

Nanocrystalline (nc) hexagonal close-packed (hcp) metals are rarely observed to deform by twinning, which is contrary to face-centered cubic metals. Here we report that, after alloying Mg with 10 at.% Ti, deformation twins are observed in an nc Mg–Ti alloy processed by mechanical attrition. The formation of deformation twins is attributed to the alloying effect, which may change the energy path for twinning. These results point to a promising approach to design nc hcp alloys for superior mechanical properties.