Refinement of second phase particles in creep-resistant iron aluminides using high-temperature severe plastic deformation

Trabajo presentado en el TMS Annual Meeting and Exhibition 2012, celebrado en Orlando, FL (Estados Unidos), del 11al 15 de marzo de 2012Severe plastic deformation (typically by Equal Channel Angular Pressing or High Pressure Torsion) is useful for processing ductile materials to obtain fine grain sizes. This study uses multidirectional high strain forging at high temperatures in order to refine coarse second-phase particle dispersions. The materials examined are cast iron aluminide alloys containing different borides or Laves phase. Following forging to strains of about 4-6, materials have relatively coarse grain sizes with greatly refined second phase particles. It is easy to refine particles by fracture from elongated to equiaxed morphology, but further refinement requires strain levels well beyond the capability of the forging technique. The choice of alloy composition and casting conditions, as well as morphology and intrinsic mechanical behaviour of the second phase, are important for determining the evolution of particle size. Excellent creep resistance has been demonstrated after severe plastic deformation has led to extensive second phase particle refinement