OPTIMIZATION OF HOT WORKABILITY AND HOT DEFORMATION MECHANISMS IN FeAl AND Fe3Al BASED ALLOYS

The constitutive flow behaviors of powder extruded Fe-24 wt.%Al alloys prepared from gas atomized and water atomized powders have been examined in the hot working range using isothermal compression tests in a wide strain rate range with a view to optimize their hot workability and evaluate the mechanisms of hot deformation. The stress-strain curves for both these materials exhibited flow softening at strain rates above 1 s-' while steady-state behavior was observed at lower strain rates. Using the standard kinetic rate equation to relate the flow stress with temperature and strain rate, an apparent activation energy of 430-465 kJ/mole has been evaluated and this value is much higher than that for diffusion of Fe or A1 in FeAl. On the basis of the strain rate sensitivity of flow stress as a function of temperature and strain rate, processing maps have bee