Refinement of second phase dispersions in iron aluminide intermetallics by high-temperature severe plastic deformation

Abstract

Severe plastic deformation has been carried out in some iron aluminide alloys by repeated high-temperature forging and used to refine the dispersion of cast-in second phase particles. The second phases considered range from brittle Laves phases to tougher boride phases, with both apparently refined in the same way by the forging. It appears that refinement is mostly determined by the initial morphology of the second phase particles, with elongated particles being broken towards an equiaxed shape. A relatively uniform distribution of fine second phase particles, such as would be needed for good high-temperature creep resistance, requires very high levels of imposed plastic strain on initially fine elongated particles.