Effect of hydrogen on the formation of the structure and phase composition in the Ti2AlNb-based alloy

Effect of hydrogen on the structure of quenched orthorhombic titanium aluminide-based alloy and phase transformations during subsequent heating

“…It should be noted that the β solid solution is ordered with the formation of the В2 structure (in the text, it is called β 0 ). As was shown in [7], the hydrogen introduction suppresses the formation of the α 2 phase during quenching; this results in the formation of a two phase (О + β 0 ) structure (Fig. 1b).…”

“…The choice of the quenching temperature was due to data available in [7]. It was shown in [7] that, at this tem perature, first, no grain growth takes place in the β phase and, second, the amount of the β phase capa ble of decomposition during subsequent aging is sig nificant (50 and 70% in Alloys 1 and 2, respectively).…”

“…The chemical composition of the alloy (at %) is Ti-24.3 Al-24.8 Nb-0.1 Zr-0.6 Mo-0.3 Si [7] and corresponds to the Ti 2 AlNb based intermetallics (O phase). The samples were hydrogenated at 900°С using gaseous hydrogen at a pressure of to 80 kPa and using a Sieverts type apparatus.…”

“…2 that, after the quenching of Alloy 1, significant amounts of α 2 and O phase plates are fixed in the β 0 matrix. According to the data of the earlier study [7], the larger plates are the α 2 phase; O phase plates are smaller and located between α 2 phase plates. The matrix β 0 phase is observed in the form of thin layers between plates (Fig.…”

“…Studies performed at the Tsiolkovskii Moscow State Aviation Technological University showed hydrogen induced plasticity effects, which were found to be useful in improving the production technology of half finished products and articles made from hardly deformed tita nium alloys [2,3], which includes hydrogen heat treatment (HHT) [4][5][6]. Previously, we considered the effect of hydrogen on the formation of phase com position and structure of Ti 2 AlNb base alloy during quenching from different temperatures [7]. It was shown that the hydrogen incorporation suppresses the formation of α 2 phase in this alloy and decreases tem peratures of transformation into the single phase β and disordered (B2 → A2 transition) states during heating.…”