THE INFLUENCE OF COMPOSITION ON THE ENVIRONMENTAL EMBRITTLEMENT OF FE3AL ALLOYS

This paper reviews recent research on embrittlement of iron aluminides at room temperature brought about by exposure to moisture or hydrogen . The tensile and fatigue crack growth behavior of several Fe-Al alloy s, ranging in aluminum content from 16-35 at.%, are described. Some al loys also contain small amounts of Nb, Zr or C. It will be shown that tensile ductility and fatigue crack growth behavior are dependent on c omposition, type and degree of long range order, environment, humidity level and frequency. Environments studied include vacuum, oxygen hydr ogen gas and moist air. All cases of embrittlement are ultimately trac eable to the interaction of hydrogen with the lattice. (C) 1997 Elsevi er Science S.A.