Experimental characterization of dislocations in deformation induced planar boundaries of rolled aluminium

Dislocations in 2 geometrically necessary boundaries in a grain near the 45°-ND rotated cube orientation in 10% rolled 99.996% pure Al were investigated by detailed transmission electron microscopy. In these two boundaries dislocations with all six Burgers vectors of the ½<110> type expected for fcc crystals were observed but dislocations from the four most active slip systems dominated. The dislocations with Burgers vectors not corresponding to one of the expected active slip systems are primarily interpreted as being the result of dislocation reactions in the boundary. Two main types of dislocation networks in the boundaries were observed: (1) 3 sets of dislocations in a hexagonal network all having Burgers vectors in the slip plane with which the boundary aligned. Two of these come from the active slip systems, the third is attributed to dislocation reactions. (2) 4 sets of dislocations of which one was a Lomer lock formed by two other dislocation sets. This type of boundary contains dislocations coming from both of the slip planes expected active.