Yield strength anomaly and the environmental effect in FeAl. Final report for the period September 1, 1996 - August 31, 2000

The aim of the work here was to understand both the yield anomaly in FeAl, which was first noted by the P.I. and collaborators, and the effect of environment on the fracture of FeAl. The progress in these areas is outlined below. A model for the yield anomaly developed as part of this work served as the basis for a successful proposal to NSF to study the yield anomaly in other B2 compounds. The effects of vacancies and of boron on flow and fracture at room temperature were also addressed. Recrystallization and grain growth were studied In both FeAl and Ni{sub 3}Al. Strain-induced ferromagnetism was studied in FeAl and a model for the paramagnetic-to-ferromagnetic transition was developed based on antiphase boundary tubes. A successful proposal was also submitted to NSF on this topic. Finally, in addition to a number of papers and Presentations on our experimental work, several invited presentations and published reviews, including a major review in International Material Reviews, on the mechanical properties of either FeAl or B2 compounds were made