Production of iron based superalloys by the method of mechanical alloying and investigation of their properties

PRODUCTION OF IRON BASED SUPERALLOYS BY THE METHOD OF MECHANICAL ALLOYING AND INVESTIGATION OF THEIR PROPERTIES (Ph. D. Thesis) Yusuf KILINÇ GAZI UNIVERSITY INSTITUTE OF SCIENCE AND TECHNOLOGY January 1999 ABSTRACT In this study, high energy ball mill with 0.55 HP and variable speeds of 800- 1400 rpm was designed and produced. The grinding tank of the attritor has 360-750-1000-1500 and 2000 cc loading capasityies. Fe-Cr-Al203 powders were milled for 1,2,10,24 and 48 hours durations by using different diameter steel balls. The investigation of mechanically alloyed powders were carried out by SEM and EDAX and analyses were done X-RD. The most suitable ball diameter and alloying time were determined. It was found that the attritor works as planned and mechanical alloying was perfomed as desired works properly. Samples were produced from 48 hours milled powders by applying hot pressing, homogenization heat treatment, high temperature oxidation and secondary recrystallization processes. The microhardness of the samples were measured at different steps and analysed by optical and electron microscope. Microstructure of the produced samples was compared with that of conventional iron based superalloys that produced commercially. Science code : 626.20.01 Key Words Mechanical Alloying, Hot Pressing Oxidation, Page number : 128 Superviser : Assoc. Prof. Dr. Mehmet Türker