High temperature creep behavior of oxide dispersion strengthened NiAl intermetallics

The intermetallic compound NiAl is a promising candidate material for high-temperature applications, provided its creep strength can be raised by some strengthening strategy. Oxide-dispersion strengthened (ODS) NiAl has been produced by powder-metallurgical methods and its creep behavior at temperatures up to 1723 K (1450 degrees C) has been studied. Exceptional creep properties, with high stresses and stress sensitivities when compared to dispersoid-free NiAl, are found, which confirms the effectiveness of dispersion strengthening in this material. The creep behavior is interpreted in the light of creep models. Detachment-controlled models satisfactorily describe the deformation in coarse-grained ODS-NiAl, but modifications are necessary for fine-grained material. In technical terms, ODS-NiAl recommends itself as a strong, light and oxidation-resistant high-temperature alloy for applications up to 1700 K. (C) 1998 Acta Metallurgica Inc.