Microstructures observation and hot compressing tests of TiAl based alloy containing high Nb

Ti-Al based alloys containing high Nb are currently under extensive attenti on because Nb is the most effective element improving their mechanical prop erties at high temperature (HT). However, high Nb addition might generate t he third phase, degrading their mechanical properties, which can keep alpha (2) + B-2 + gamma ternary phases existing. A new Ti-Al based alloy with hig h Nb content, whose nominal chemical composition is Ti-45Al-8.5Nb-0.3W-0.05 Y at.%, was developed through hot compressing tests. The results show that the alloy with near fully lamellae (NFL) microstructure has higher ultimate compressing strength (sigma(p)) and 0.2% proof strength (sigma(0.2)) than those with Duplex (DP) microstructure at HT, but maximum compressing rate ( Delta l/l) inversely The combination of Nb atom solid solution strengthenin g and yttrium oxide precipitation strengthening contribute to their HT stre ngth, refine grains bring the better plasticity. Simultaneously, the micros tructure evolution was observed using light microscope (LM) and transmissio n electron microscope (TEM) after thermo-mechanical process, such as lots o f stacking faults, twins, and jog of stacking faults and twins, which resul t from the coordination of deformation. Published by Elsevier Science S.A.