抄録
The microstructural changes during the sintering process of Merl 76 powder and the solidification process of melted Merl 76 powder were investigated through DTA, microstructural observation and EPMA.
DTA during the sintering and the solidification processes of Merl 76 powder detected five endothermic and five exothermic reactions, respectively. Although the phase reactions during both processes occurred in approximately the same temperature range, the microstructural observations and EPMA analyses of the phases revealed that the phase reactions during the sintering process were not reversed to those during the solidification process. The microstructures observed during the sintering process approached those found during the solidification process after holding in the respective temperature ranges.
Rapid densification of Merl 76 powder compacts occurred in the temperature range of 1st reaction, which corresponded to the incipient melting. The microstructure of Merl 76 powder was consisted of fine dendritic structure. In the temperature range of 1st reaction, the liquid phase appeared in the regions between the dendrite arms and the amount of the liquid phase increased, changing its composition with increasing holding time.
