Abstract
In the previous reports, rapid densification and division into smaller particles have been observed in the initial stage of liquid phase sintering.
In order to clarify these phenomena, the rate of eutectic liquid formation and penetration of this liquid into solid particles have been measured in the compacts of 80Cu-20Ag and division mechanism was deeply investigated in Cu-Ag, Cu-Bi and Cu-Pb systems using poly-crystalline and single-crystalline spherical Cu powders.
The following results were obtained by microscopic observation and X-ray analysis.
1 Cu-Ag eutectic liquid was formed for only a few seconds at eutectic temperature.
2 In Cu-Ag, the rate of penetration of the liquid into the solid particles was 0.1mm/min at 850°C.
3 The division of Cu particle into smaller particles occurred only in poly-crystalline Cu powders by grain boundary corrosion of liquid and was not observed in single-crystalline powders.
4 In systems with complete wettability and appreciable solubility (Cu-Ag, Cu-Bi), Cu particles were divided into original grain size of particles but, in the case of incomplete wettability (Cu-Pb), division of particles was not observed.
