Three-layer defects in quenched aluminium

Abstract
Transmission electron microscopy observations have been made of the form of vacancy clusters in pure aluminium quenched from 600°C into silicone oil at 30°c. A new three-layer planar vacancy cluster lying on {111} planes with a Burgers vector along 〈111〉 directions has been found. A model for its structure has been put forward which is based on the unfaulting behaviour of the defect, as observed in situ in the electron microscope, and on the electron contrast behaviour of its component dislocations.