Including: Peritectic Reaction

A peritectic reaction is a reaction where a solid phase and liquid phase will together form a second solid phase at a particular temperature and composition - e.g.

Liquid + alpha --> beta

These reactions are rather sluggish as the product phase will form at the boundary between the two reacting phases thus separating them, and slowing down any further reaction. Peritectics are not as common as eutectics and eutectiods, but do occur in some alloy systems. There's one in the Fe-C system.

Diagram showing the Peritectic reaction, where a liquid and solid together form a new solid phase.

Associated terms: alpha, beta, eutectic, eutectoid