Quaternary and Multicomponent Systems

A join in a quaternary system may occasionally be a true binary join within the quaternary system; that is, the composition of all solid and liquid phases appearing on the join may be expressed in terms of the compositions at the extremities of the join. In the case of eutectic melting in a complex quaternary system involving binary and ternary compounds, the particular quaternary compatibility tetrahedron involved will be a true quaternary tetrahedron within the main quaternary system. The system B₂O₃-Al₂O₃-SiO₂-P₂O₅ is an example of a quaternary system where detailed phase equilibrium research is needed in binary and ternary subsystems before the final solid model of the quaternary system can be constructed. Modem ceramics has taken a turn toward compositionally simpler systems, but, on the other hand, the computer has taken over on the design of multicomponent glass, glaze and enamel compositions.