An investigation was performed to apply the M3/2 grade high speed steel for metal injection molding using both prealloyed and elementally blended powders. The injected samples were subjected to a debinding step in gas atmosphere at a ratio that affected the carbon content of the material. The carbon content ranged from 1.4wt.% to 1.43wt%. with increasing content up to 80% in atmosphere for the prealloyed powders. The carbon contents of the elementally blended powders exhibited 1.44wt.% and 1.62wt.% at 10% and 20% gas, respectively. This level decreased to 0.17wt.% upon increasing the content. The sintered density of both powders increased rapidly as the temperature reached the liquid phase forming temperature. After forming the liquid phase, the density rapidly increased to the optimum sintering temperature for the prealloyed powders, whereas the density of mixed elemental powders goes up slowly to the optimum sintering temperature. The optimum sintering temperature and density are 126 and 97.3% for the prealloyed powders and 128 and 96.9% for the elementally blended powders, respectively. The microstructure of the specimen at the optimum sintering temperature consisted of fine grains with primary carbides of MC and type for the prealloyed powders. The elementally blended powders exhibited coarse grains with eutectic carbides of MC, and type.

Microstructure and phase transformation of mechanically alloyed TiNi powders added to aluminium matrix for enhancing the damping properties were studied. Four compositions between 48.5 and 51.5 at% Ti intermetallic compounds were selected to control the fraction of martensite phase. Mechanically alloyed TiNi powders were heat-treated at vacuum of torr for crystallization. Ball milled AI/TiNi composite powders were swaged at room temperature and rolled at 450 . After mechanical alloying for 10 hours, Ti and Ni elements were alloyed completely and amorphous phase was formed. Amorphous phase was crystallized to martensite (Bl9') and austenite(B2) after heat treating for 1 hour at the temperature of 850 , and TiNi, intermetallic compound was partially formed. Considerable amount of martensite phase was remained after swaging and rolling.

지르코니아 분말 합성 시 500ppm의 Polyvinyl Alcohort(PVA) 첨가에 의해 입자가 균질하게 분산된 안정된 지르코니아 현탁액을 제조하였다. 이러한 현탁액으로부터 원심분리에 의해 제조된 충진체는 PVA를 첨가하지 않은 시편의 충진체에 비해 기공의 크기가 작은 고밀도의 균질한 충진체였다. 이 충진체를 사용하여 소결한 결과, 지르코니아 소결에 있어서는 비교적 낮은 온도인 1250˚C에서도 상대밀도가 98%인 고밀도의 단사성 지르코니아 소결체를 제조할 수 있었다.

MATERIAL AND PROCESS VARIABLES THAT STRONGLY AFFECT THE CORROSION RESISTANCE OF PA4 STAINLESS STEELS, INCLUDE : ALLOY COMPOSITION, POWDER CLEANLINESS, NITROGEN, OXYGEN AND GARBON CONTENTS, CHROMIUM DEPLETION DUE TO SURFACE EVAPORATION AND SINTERED DENSITY. THE OPTIMUM PROCESS PARAMETERS FOR DELUBRICATION AND SINTERING THAT RESULT IN LOWEST LEVELS OF NITROGEN, OXYGEN AND CARBON AND MINIMUM LEVELS OF CHROMIUM DEPLETION WILL BE PRESENTED, FOR A NUMBER OF AUSTENTIC AND FERRITIC STAINLESS STEELS. THE EFFECT OF SINTERED DENSITY ON THE CORROSION RESISTANCE OF BOTH AUSTENITIC AND FERRITIC GRADES OF STAINLESS STEEL WILL ALSO BE COVERED.