Investigation of rheological properties of mechanically alloyed and turbula processed composite powder PIM feedstock by capillar rheometer

Abstract

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 threedimensional 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 200°C. 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.