Dislocation processes during the deformation of MoSi2 single crystals in asoft orientation

In situ straining experiments in a high-voltage electron microscope have be en carried out for the first time on MoSi2 single crystals between 800 and 1000 degrees C along a soft [201] orientation. Dislocations with 1/2[111]Bu rgers vectors were formed in localised sources leading to almost planar sli p. The dislocations were strictly arranged along 60 degrees and edge orient ations and moved at high velocities or in a viscous way. These observations are correlated to the macroscopic deformation behaviour and interpreted by the formation of intrinsic point defect atmospheres around the moving disl ocations. The model explains the 'inverse' dependence of the strain rate se nsitivity of the flow stress on the strain rate. (C) 1999 Elsevier Science S.A. All rights reserved.