RAPIDLY SOLIDIFIED FERROUS ALLOYS.

The allotropic behavior of ferrous alloys provides novel effects in rapidly solidified materials arising from competition between stable and metastable primary solidification products, and the suppression of martensitic transformations in fine microstructures. The principal benefit of RSP in hot consolidated material is associated with the refinement and compositional modification of inclusion phases which then act as ultra-stable grain refining dispersions. Grain refinement via TiB//2 dispersions and thermomechanical treatment has provided substantial ductility enhancement in Fe//3Al alloys. The grain coarsening resistance of RSP steels allows the use of high temperature solution treatments to improve sharp-crack K//I//C toughness in stage I tempered martensitic steels, and provides improved blunt-notch toughness in these steels as well as secondary hardening matrix tool steels and microalloyed ferritic steels.