Weak-beam study of glide dislocations in h.c.p. cobalt

This is the authors' abstract. We don't add key points for this paper.

The weak-beam method of electron microscopy has been used to analyse the Shockley partial dislocations in a pure h.c.p. metal. Single crystals of cobalt were grown oriented for basal slip and deformed in compression. The dissociation of the basal glide dislocations into partials is resolved; tho arrangement of the magnetic domains does not influence the splitting width of the partials. From a careful analysis of the observed image peak separations, a room-temporature stacking-fault energy γ = 27 ± 4 mJ m−2 is doducod. The basal glide dislocations contain many jogs. Frequently tho sequence of the partials is reversed at a jog, which leads to the conclusion that the dislocation is jogging over an odd number of lattico planes and has a stacking fault of the same intrinsic type I2, on both sides of the jog. It should be pointed out that in the f.c.c. structure this behaviour has not been observed, since tho reversed sequence of the partials would lead to a glide dislocation containing an extrinsic fault.