In
chemistry,
materials science, and
physics, the 'liquidus' is a line on a
phase diagram above which a given substance is stable in the
liquid phase. Most commonly, this line represents a transition
temperature. The liquidus may be a straight line, or it may be curved, depending upon the substance. The liquidus is most often applied to
binary systems such as
solid solutions, including
metal alloys.
The liquidus may be contrasted to the
solidus. The liquidus and solidus do not necessarily align or overlap; if a gap exists between the liquidus and solidus, then within that gap, the substance is not stable as either a liquid or a
solid.