Straining experiments along a soft [201] orientation were performed for the first time in situ in a high-voltage electron microscope on single crystals at temperatures of between 800 and 1000C. Dislocations with ½<111> Burgers vectors were formed in localized sources and led to almost-planar slip. The dislocations were arranged along 60º and edge orientations, and moved at high velocities or in a viscous manner. These observations were correlated with the macroscopic deformation behaviour, and were explained in terms of the formation of intrinsic point defect atmospheres around the moving dislocations. The model explained the inverse dependence of the strain-rate sensitivity of the flow stress upon the strain rate.

Dislocation Processes during the Deformation of MoSi2 Single Crystals in a Soft Orientation. S.Guder, M.Bartsch, M.Yamaguchi, U.Messerschmidt: Materials Science and Engineering A, 1999, 261[1-2], 139-46