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° and 109.5° 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 boun...

Although the favored glide planes in hexagonal close-packed Zr are prismatic, screw dislocations can escape their habit plane to glide in either pyramidal or basal planes. Using ab initio calculations within the nudged elastic band method, we show that, surprisingly, both events share the same thermally activated process with an unusual conservative motion of the prismatic stacking fault perpen...

Trapping of electrons in stacking fault SF interface states may lower the energy of a SF more than it costs to form the SF. This “electronic stress” driving force for SF expansion is evaluated for single and double stacking faults in 4H-SiC in terms of a two-dimensional free-electron density of states model based on first-principles calculations. In contrast with previous work, which claimed th...