Liquidus and solidus

The solidus is the locus of temperatures (a curve on a phase diagram) below which a given substance is completely solid (crystallized).

Liquidus and solidus are mostly used for impure substances (mixtures) such as glasses, metal alloys, ceramics, rocks, and minerals.

Lines of liquidus and solidus appear in the phase diagrams of binary solid solutions,[2] as well as in eutectic systems away from the invariant point.

As the system is cooled below the liquidus temperature, more and more crystals will form in the melt if one waits a sufficiently long time, depending on the material.

Alternately, homogeneous glasses can be obtained through sufficiently fast cooling, i.e., through kinetic inhibition of the crystallization process.

The equilibrium phase diagram of a solid solution of made up of mixtures of α and β. The upper curve is the line of liquidus, and the lower curve is the line of solidus.
Liquidus temperature curve in the binary glass system SiO 2 -Li 2 O