CREEP IN STOICHIOMETRIC BETA NiAl.

The Physical and Mechanical Metallurgy of NiAl

“…Although a stress exponent of 7 is higher than is characteristic for class M behavior, such high values have been observed in several class M materials (Ashby 1972). Observations of subgrain formation after high-temperature deformation (Kanne, Strutt, and Dodd 1969;Yang and Dodd 1973); operation of normal primary creep behavior under both constant load and constant crosshead speed tests (Strutt, Dodd, and Rowe 1970;Whittenberger 1987Whittenberger ,1988; strain rate transient test results (Yaney and Nix 1988;; and strengthening via a reduction in grain size (Whittenberger 1988) are all consistent with class M behavior. Consequently, high-temperature creep in binary NiAI is apparently climb controlled over most stresses and temperatures.…”

“…Certain orientations may have higher creep strengths that could be used to advantage in applications such as turbine blades. During experiments with singlephase binary compounds at temperatures above approximately 1050 K, some investigators have observed significantly higher creep strengths for hard-orientation crystals (Strutt, Dodd, and Rowe 1970;). However, other investigators have not observed significant anisotropy (Pascoe and Newey 1968b;Whittenberger, Noebe, Cullers, Kumar, and Mannan 1991).…”