IN-SITU OBSERVATION OF PERITECTIC GROWTH WITH FACETED INTERFACE

In-situ observation of peritectic reaction of the acetamide-salicylic acid system was performed. The peritectic reaction proceeded by facete d growth of the secondary phase into the liquid and dissolution of the primary phase except the high growth rate. The secondary phase did no t tend to grow along the primary-phase/liquid interface. As the primar y phase size or the growth rate decreased, the primary phase tended to dissolve ahead of the growing interface of the secondary phase. The u ndercooling of the growing interface from the peritectic temperature i ncreased with increasing growth rate. The undercooling should include the kinetic undercooling of the faceted growing interface. The primary phase size was an important factor of the dissolution, since the driv ing force and the mass transfer rate depend on the size.