Grain-boundary dissociation by the emission of stacking faults.

Abstract

A range of $〈110〉$ symmetric tilt grain boundaries (GB's) are investigated in several fcc metals with simulations and high-resolution electron microscopy. Boundaries with tilt angles between 50.5\ifmmode^\circ\else\textdegree\fi{} and 109.5\ifmmode^\circ\else\textdegree\fi{} dissociate into two boundaries 0.6 to 1.1 nm apart. The dissociation takes place by the emission of stacking faults from one boundary that are terminated by Shockley partials at a second boundary. This is a general mode of GB relaxation for low stacking fault energy metals. The reasons for the occurrence of this relaxation mode are discussed using the theory of GB dislocations.