TEM of Dislocations in AIN

Sintered AIN specimens were deformed by Vickers hardness (HV) indentations. Compared with Al 2 O 3 the HV hardness values indicate a much higher plasticity of AIN at room temperature, but above 600°C a higher ductility for Al 2 O 3 . Deformed AIN specimens were examined by transmission electron microscopy. Basal and prismatic glide with the slip systems (0001) 〈1120〉 and {1 1 00}〈11 2 0〉 were frequently observed. This results in four linearly independent slip systems. The critical resolved shear stress for single prismatic slip seems to be even smaller than for basal slip. However, thermally activated dislocation reactions are frozen up to at least 1000°C. Thus, prismatic slip is suppressed as soon as more than one slip direction is activated.