1. General presentation

In metallurgy, a phase diagram is a graphic representation of the phases present in an alloy as a function of its chemical composition and equilibrium temperature. In some cases of volatile metals, pressure must also be taken into account, but we will only deal here with cases where this variable has little influence on the equilibrium of condensed solid or liquid phases. For volatile systems, we will only consider equilibria obtained in a closed volume under the natural pressure imposed by the system itself.

Phase diagrams are widely used in metallurgy:

• in processing, the phase diagram indicates the areas of appearance of desired phases or, conversely, phases that are harmful for certain uses and whose formation should be avoided;

• In heat treatment or transformation metallurgy, the...