Characterization and interpretation of the morphology of a Mg₂Sn precipitate with irrational facets in a Mg–Sn–Mn alloy

Abstract

The crystallographic morphology of β-Mg₂Sn precipitates at (near) Burgers orientation relationship (OR) with respect to the α-Mg matrix in a Mg–Sn–Mn alloy was investigated by transmission electron microscopy (TEM). Two irrational facets of the precipitates were found to be F1 ∼// (−1 1 0.74)_β and F2 ∼// (−1 1 −3.1)_β. The facets are interpreted according to interfacial structures. The presence of a singular dislocation structure in F1 requires a small rotation of 0.21° from the Burgers OR. The calculated morphology is consistent with the observations.

Keywords:

• magnesium alloy
• precipitation
• interface
• simulation

Acknowledgements

The experimental alloy was prepared by the group of Professor R.-S. Chen from Institute of Metal Research, Chinese Academy of Science. Valuable discussions with Professor R.-S. Chen and L. Gao are gratefully acknowledged. This work made use of the resources of the Beijing National Center for Electron Microscopy and was supported by National Basic Research Program of China (No. 2009CB623704) and National Nature Science Foundation of China (No. 50971076).