Inversion domain boundaries and dislocations observed by TEM in deformed aluminium nitride

Planar defects in aluminium nitride, presumably inversion domain boundaries (IDBs) related to the presence of oxygen, are studied by TEM in sintered and hot-pressed materials, after plastic deformation at elevated temperatures. Mechanical testing does not change the number and characteristics of IDBs but puts into evidence dislocation trapping at these defects. The origin of dislocation trapping at IDBs is discussed. It is shown that shearing a clean curved IDB by a perfect dislocation locally changes the number of wrong atomic bonds. Nous avons etudie par MET, dans deux nuances de nitrure ďaluminium. fritte et presse a chaud, et apres deformation plastique a haute temperature, les defauts plans bidimensionnels identifies a des parois de domaines ďinversion (IDBs) et relies a la presence ďoxygene. Les essais mecaniques ne modifient pas le nombre et les caracteristiques des IDBs mais font apparaitre que ces defauts piegent les dislocations. Nous discutons la cause de cet effet en montrant que le cisaillement ďun IDB courbe, exempt ďimpuretes, par une dislocation parfaite modifie localement le nombre de mauvaises liaisons atomiques.