Effect of oxygen addition on mechanical properties of TiAl at 293–1273 K

Abstract

Mechanical properties of Ti−50, −53, and −56 at.% Al alloys doped with 0, 0.1, 0.2 and 0.3 mass% oxygen have been studied in compression tests at temperatures from 293 K to 1273 K in a vacuum. The yield stress in Ti−50 at.% Al alloy increased by about 1.5 times owing to the addition of 0.3 mass% oxygen at all testing temperatures. In Ti−53 and −56 at.% Al alloys the increases of yield stress due to the addition of oxygen were not as pronounced as those in Ti−50 at.% Al alloys. The work hardening coefficients increased at 293–873 K but they decreased at 1073–1273 K with increasing oxygen and aluminum content. Insoluble particles extracted isolated by a mixed acid from TiAl alloys were α-Al2O3 phase and the amount of α-Al2O3 phase increased with increasing aluminum and oxygen content. The increase of yield stress at all testing temperatures occurred owing to the solid solution hardening of oxygen in Ti−50 at.% Al alloy and the dispersion strengthening of α-Al2O3 in Ti−53 and Ti−56 at.% Al alloys.