The Peritectic Reaction in the System Pb–Bi

Abstract

Nucleation and growth in binary peritectic reactions are discussed, particular attention being given to the nucleation of the second solid phase and to alternative courses for the reactions. The system Pb–Bi has been examined, using specimens cooled at various rates and directional freezing methods. It is concluded that in this case the peritectic reaction may illustrate an example in which the second solid does not nucleate directly upon the primary, proceeding by a somewhat different mechanism to that generally assumed. It is shown that the peritectic point and limit are very flexible under non-equilibrium conditions.