Abstract The initial oxidation products of Ti-22Al-xNb(x=0-30%, mole fraction) alloy at 1 000 ℃ were calculated by phase diagram calculation. The changes of mass fraction and phase composition of Ti-22Al-27Nb and Ti-22Al-15Nb alloys at the initial stage of oxidation at this temperature were predicted. The results show that, with the increase of oxygen partial pressure, Bcc_B2 phase in the matrix changes to Hcp_A3 phase to dissolve the increased O(oxygen). The oxidation order of the elements in the alloy is Al, Ti, Nb. Al2O3, Halite(TiO) and NbO appear at the oxygen partial pressures of 4.72×10-32 MPa, 4.11×10-30 MPa and 5.53×10-25 MPa, respectively. With the increase of oxygen partial pressure, the oxidation products of Ti and Nb tend to higher oxygen content. Compared with Ti-22Al-27Nb, the mass fractions of NbO and NbO2 in Ti-22Al-15Nb alloy decrease obviously, while the mass fraction of Al2O3 increases obviously.
YANG Jiajun,LIU Libin,ZHAO Yun, et al. Thermodynamic analysis of Ti2AlNb-based alloy in the initial stage of high temperature oxidation[J]. Materials Science and Engineering of Powder Metallurgy, 2020, 25(2): 98-103.
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2020, Vol. 25 
