EFFECT OF ANNEALING ON THE PHASE COMPOSITION AND MICROHARDNESS OF Β-TI ALLOYS TI-ZR-NB AND TI-10MO-8NB-6ZR

Abstract

This paper presents comparative  studies of structural and mechanical properties of new β-titanium alloys Ti-10Mo-8Nb-6Zr and Ti18Zr15Nb  subjected to quenching and subsequent annealing. Ti18Zr15Nb and  Ti10Mo8Nb6Zr alloys are practically single-phase after quenching.  Annealing leads to the appearance of a finely dispersed α-phase, which leads to an increase in the microhardness of Hv. The most intense release of the α-phase occurs at a temperature of 450 °C. In the hardened Ti18Zr15Nb alloy, after annealing 450 °C for 12 hours, up to 25% of the α-phase is released anda significant (up to 70%) increase in Hv occurs as a result of aging. In  Ti10Mo8Nb5Zr alloy, afterquenching and annealing 450 °C with 12 h, the α-phase is released in an amount of about 4%. This means that the Ti10Mo8Nb6Zr alloy is more stable to annealing compared to Ti18Zr15Nb.After annealing at 450 °C, the  microhardness of the Ti10Mo8Nb6Zr alloy increases from about 300to 500 units, which is also apparently due to the release of a finely dispersed α-phase and ω-phase.