boundary curve

A phase diagram is a graph that illustrates the conditions under which different phases of a substance (solid, liquid, or gas) can exist. These diagrams plot variables like pressure and temperature.

The lines on a phase diagram represent boundary curves, where two phases can coexist in equilibrium. For example, the line between solid and liquid shows melting points at different pressures. The point where all three curves meet is the triple point, where solid, liquid, and gas phases exist together. Areas separated by these curves indicate conditions where only a single phase is stable. Phase diagrams are crucial for understanding material properties and industrial processes.12