Hydrogen effects on the character of dislocations in high-purity aluminum

The effect of hydrogen in solid solution on the edge/screw character of dis locations has been investigated by deforming samples of high-purity aluminu m in a gaseous hydrogen environment in situ in a controlled environment tra nsmission electron microscope. Solute hydrogen was found to stabilize edge segments of dislocations, which inhibited, and in some cases stopped disloc ations from cross-slipping. Removal of hydrogen from the sample allowed the cross-slip process to continue. These observations provide an explanation for the macroscopic observation that hydrogen in solid solution can promote slip planarity. (C) 1999 Acta Metallurgica Inc. Published by Elsevier Scie nce Ltd. All rights reserved.