Structure and Phase-Composition Formation in a Quenched Intermetallic VTI-4 Titanium Alloy with Various Hydrogen Contents during Isothermal Treatment: I. Treatment at 950 and 1000°C

The formation of the phase composition and structure in a quenched titanium alloy based on the Ti₂AlNb intermetallic compound with an initial hydrogen content and with 0.3 wt % hydrogen is studied during isothermal holding at temperatures of 950 and 1000°C for 10–300 min. The introduction of hydrogen into the alloy is shown to decrease the decomposition intensity of the metastable B2 phase under the temperature conditions under study. When the isothermal holding temperature decreases to 950°C, the decomposition dynamics at various hydrogen contents intensifies, which leads to a decrease in the volume fraction of the β phase by 10% compared to holding at 1000°C. After high-temperature isothermal treatment, the decrease in the microhardness of the alloy is not significant, and the microhardness is only 10–30 HV_0.05 less than the values obtained for the quenched single-phase state.