INTRINSIC DUCTILITY OF FEAL SINGLE-CRYSTALS

The room-temperature ductility of FeAl is significantly reduced by env ironmental embrittlement caused by the water vapor present in air. Sin ce Fe-rich FeAl can fail by either transgranular or intergranular frac ture in both wet and dry environments, the relative effects of the env ironment on grain boundaries versus the grain interior are not known a nd warrant study. In this investigation, the effect of test environmen t on the tensile properties of single crystals of Fe-40Al was studied in order to eliminate the effects of grain boundaries. It was found th at the single crystals exhibited significantly higher room-temperature ductilities when tested in a moisture-free environment, although '001 ' cleavage fracture initiation remained the same as for samples tested in air. At the 40 at% Al level, the degree of environmental embrittle ment in the single crystals was similar to that observed in fine-grain ed binary polycrystals and B-doped polycrystals.