POWDER METALLURGY, cilt.47, sa.1, ss.49-54, 2004 (SCI-Expanded)
In this study, Fe Cr-Al2O3-Ti Y2O3 powders, used for superalloy production, were milled in a high energy mechanical alloying attritor and processed in a ball containing turbula mixer with a three-dimensional action for 1, 2, 10, 24 and 48 h. The effects of milling process and time on mean particle size, distribution and morphology were analysed by SEM and a laser particle size analyser. Mechanically alloyed and turbula mixed composite powders were then mixed with a polyethylene based binder to obtain PIM feedstock. The flow behaviour of the powder feedstock was investigated by capillary rheometer at temperatures between 155 and 200degreesC. It was found that, increasing the milling time resulted in spherical shaped particles in the attritor and flakelike particles, with a reduced particle size. in the turbula mixer. Attritor milling led to the feedstock flowing more easily and better results for PIM, whereas turbula mixed powders were found not to be suitable for PIM because of the flakelike structure.