The Van der Waals model of a binary mixture in which $b$ is constant and $a$ depends quadratically on the composition possesses a global phase diagram in a space of five thermodynamic fields. The salient features of this phase diagram are worked out and compared with those found previously in a three-component model.

• Received 19 October 1977

DOI:https://doi.org/10.1103/PhysRevA.17.1139