A Mechanism of Formation of Dislocation Dipoles in Face-Centered Cubic Crystals

A mechanism of formation of dislocation dipoles was discussed without assuming climb nor cross slip of dislocations in face-centered cubic crystals. The greater part of Frank-Read sources in the face-centered cubic crystals are spiral or cone dislocation sources, which cause homogeneous slip. When dislocations producing the homogeneous slip meet with an intersecting dislocation with Burgers vector crossing the slip plane, the formation of jogs differs considerably from that in dislocations on the same atomic plane. A jog in each dislocation can be removed leaving behind a large jog, which results in a dislocation dipole. The geometries of such interactions were illustrated for some simple cases. The difference in dislocation arrangements between pure metals and alpha-brass or copper-aluminium alloys was attributed to the effect of short range order hardening, which hinders the operation of the spiral or cone dislocation sources.