A ten per cent plastic deformation of polycrystalline aluminium nitride, at a temperature ranging from 1500 to 1650 ○C creates a new kind of intragranular defect. Observed by transmission electron microscopy, the look like torsion subboundaries created by dislocations with $1/3langle11ar{2}0
angle$ Burgers vectors and so nodes are dissociated into Shockley partials. They are located in the basal plane. In fact, these defects appear only in the plane areas of grown-in defects, the inversion domain boundaries. The formation of these faulted networks is interpreted as being the ultimate stage of the interactions between inversion domain boundaries and glide dislocations