DISPERSION STRENGTHENED FeCrAlY ALLOYS BY FLAKE POWDER PROCESSING.

Abstract

A high yield, powder metallurgy technique involving high energy (attritor) milling was utilized to produce oxide dispersion strengthened FeCrAlY alloys without the concurrent formation of chromia or chromia-containing spinels. Consolidation of powder compacts was accomplished by hot extrusion at either 982 degree C or 1093 degree C. The dispersoid present in as-extruded bar was identified as 3Y//2O//3 multiplied by (times) 5Al//2O//3 (yttrium-aluminum garnet) with an average particle size of about 300A. As-extruded 982 degree C tensile and stress rupture properties were significantly improved when compared to the same composition without dispersoid. Further improvement in stress-rupture strength was obtained by producing coarse grain structures with high aspect ratio. Two of the alloys produced responded to secondary grain growth in the as-extruded condition by both isothermal annealing and directional recrystallization.