A transmission electron microscopic study was made of samples which had been deformed along the so-called soft <101> direction at room temperature. The observations, especially those concerning sharp transitions of successive <102>-oriented segments, suggested that <102> was a particularly stable orientation for <001> Burgers vector dislocations. This was contrary to the predictions of anisotropic elasticity theory, in that the latter suggested that <102> was an unstable orientation for <001> Burgers vector dislocations. This suggested that some other mechanism operated, and anchored these dislocations along the <102> orientation. It was noted that such an anchor had to be strong enough to prevent the dislocation from rotating away from the <102> orientation in order to reduce the elastic energy. This was not difficult, because previous elasticity calculations had shown that, for <001>{010} dislocations, the elastic energy variation was extremely small when compared with that of <101>{010} dislocations. A possible mechanism for the anchoring process assumed that the cores of the dislocations were sessile along the <102> orientation. This was thought to be reasonable because the core could be highly sessile if the energy of a planar fault, on a plane which intersected the slip plane, was sufficiently low. The observation that many different <102> segments were joined via sharp junctions was suggested to illustrate that <102> was a low-mobility direction. The splitting of the dislocation core was expected to be small, because the weak beam analysis that was used revealed no visible dissociation.

X.K.Meng, A.H.W.Ngan, Z.G.Liu: Scripta Materialia, 1996, 34[6], 883-7