Abstract
SUMMARY: The advantages of the weak‐beam technique of electron microscopy for the study of small defects and dislocations are illustrated by micrographs taken of small loops in aluminium and Al–Ag alloys, GP zones and θ″ precipitates in Al + 4% Cu, and dislocation networks in Cu + 20% Zn. An estimate of 19·5 mJ m−2 (erg cm∼2) is made for the stacking‐fault energy of Cu–20% Zn from the size of extended nodes and the width of the dissociated dislocations imaged under weak‐beam conditions.