High pressure aging synthesis of a hexagonal Mg2Sn strengthening precipitate in Mg-Sn alloys

A novel hexagonal Mg2Sn strengthening precipitate has been achieved by high pressure aging (2 GPa, 400 °C) method in a Mg-9 wt% Sn alloy for the first time. The results show the particle is ellipsoid-shaped with an average diameter of 25 nm. Differing from the conventional coarse plate-like or rod-like Mg2Sn strengthening particles with face-centered cubic structure after artificial aging at ~200 °C, the formation of novel fine hexagonal Mg2Sn particles significantly improves the strength of Mg-Sn alloys together with the ductility. The high strength and ductility are mainly associated with the presence of fine strengthening precipitates and the low lattice misfit (0.025) of hexagon-on-hexagon crystallographic orientation, respectively.