A transmission electron microscopy investigation of crystallography of τ-Mg32(Al, Zn)49 precipitates in a Mg–Zn–Al alloy

The orientation relationship (OR) between τ-Mg32(Al, Zn)49 precipitates and Mg matrix is characterized by transmission electron microscopy. Two new ORs are observed. Each OR is associated with a unique morphology of the τ precipitates, i.e. the polygonal Type 1 and the capped parallelepiped Type 2. All the prominent facets in the shapes can be defined by Δg vectors in the diffraction patterns.