2016 Volume 102 Issue 7 Pages 380-388
In order to investigate the peritectic reaction, Ag-18 mass%Sn alloy has been used in this study. Approximately 10 g of this alloy was melted in the alumina crucible. Using a fine K-type thermocouple, thermal history during cooling was recorded. The peritectic reaction was observed at about 725 ºC, which corresponded to the equilibrium phase diagram. The metallographic SEM observation of the specimen, which was quenched at 725 ºC, revealed that the secondary phase, ζ phase, completely covered the primary (Ag) phase. These indicated that ζ phase easily nucleated on the primary (Ag) phase and the peritectic reaction rapidly finished. EBSD analysis showed that plural crystals of ζ phase covered on the single crystal of (Ag) phase. This also indicated that ζ phase formed easily on the (Ag) phase. The analysis of relation between temperature and phase fraction indicated that thick ζ phase rapidly formed along the (Ag) phase / liquid interface and peritectic reaction plays a major part of transformation in this alloy system formed in an isothermal cooling.
