Decomposition of the ω-phase in the equiatomic TiZr alloy under high pressure

Abstract

The phase decomposition phenomenon is found in the hexagonal ω-phase of the Ti—Zr system under high pressure. The ω → ω1 + ω2 decomposition of the equiatomic TiZr alloy occurred due to long thermobaric treatment at P = 5.5±0.6 GPa and T = 710±30 K. The chemical compositions of the ω1- and ω2-phases recovered to ambient conditions were estimated from the X-ray data to be around Ti20Zr80 and Ti83Zr17. The experimental data were used to calculate the mixing energy and the top of the decomposition curve in the isobaric T-C diagram of this system. We find that the equilibrium T-C phase diagram of the Ti-Zr system at pressures above ∼8 GPa is of the eutectoid type with the high-temperature β-phase and the low-temperature ω1- and ω2-phases.