Decomposition of a Solid Solution in the Ω Phase of the Ti-Zr System under High Pressure

Phase separation in the hexagonal ω modification of the Ti-Zr system was observed. The ω → ω1 + ω2 decomposition in an equiatomic TiZr alloy after prolonged thermal treatment at P = 5.5 ± 0.6 GPa and T = 440 ± 30°C was revealed using x-ray diffraction. It is found that the concentration dependence of the specific volume of the ω phase of Ti-Zr alloys deviates from the Vegard law to higher values. An isobaric section of the equilibrium P-T-x phase diagram of the Ti-Zr system is shown to have the shape of an eutectoid diagram at pressures higher than 8 GPa.