The model of regular solutions has been used to obtain expressions for calculating the boundaries of the region of spinodal decomposition for five-component solid solutions of III-V compounds. The stability region of the solid solution Al
x1Ga
x2In
1–x1–x2P
yAs
1–y has been estimated.
Moscow Institute of Electronic Engineering. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 11–13, December, 1993.