GRAIN-BOUNDARY DISSOCIATION BY THE EMISSION OF STACKING-FAULTS

A range of [110] symmetric tilt grain boundaries (GB's) are investigat ed in several fee metals with simulations and high-resolution electron microscopy. Boundaries with tilt angles between 50.5 degrees and 109. 5 degrees dissociate into two boundaries 0.6 to 1.1 nm apart. The diss ociation takes place by the emission of sticking faults from one bound ary that are terminated by Shockley partials at a second boundary. Thi s is a general mode of GB relaxation for low stacking fault energy met als. The reasons for the occurrence of this relaxation mode are discus sed using the theory of GB dislocations.