A model for dispersion strengthening of ordered intermetallics at high temperatures

Several aspects of dispersion strengthening in high-temperature materials can be explained by a model involving the thermally activated detachment of dislocations from the dispersoids (Rosler, J. and Arzt, E., Acta metall., 1990, 38, 671). This approach is now extended to ordered matrix materials, such as many intermetallic compounds, in which coupled superpartial dislocations surmount the dispersoids separately but in a cooperative manner. A creep equation based on the two detachment processes is developed. It is shown that several recent creep data on dispersion-strengthened Ni3Al and Fe1-xAlx can be described well by this approach. The model also suggests a strategy for optimizing such intermetallics with regard to creep strength. (C) 1998 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.