Glide mechanism of ordinary dislocations in the γ phase of TiAl

Glide mechanism of ordinary dislocations in the γ phase of TiAl alloys is studied by in situ straining experiments. A polar source and several dynamic sequences showing moving dislocations are presented. It is shown that the deformation is due to rectilinear screw dislocations anchored at many pinning points. The origin of the frictional force opposing to the dislocation movements and that of these pinning points are analysed and discussed. Experimental observations show also that an increase of temperature leads to a fast deformation by bursts of dislocations. This temperature effect is interpreted by dynamic strain ageing.