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Existing TiAl alloys used for fabricating last-stage turbine blades of jet engines are relatively cost-prohibitive and unreliable, particularly for use in next-generation engines. The present study was conducted to address these issues by uncovering new TiAl alloy compositions with a focus on improving machinability and impact resistance. Ternary alloys integrated with V or Cr were examined and compared with two commercial TiAl alloys (TiAl4822 and TNM alloy). V and Cr were selected because they are significantly cheaper than the Nb added to existing commercial TiAl alloys and can improve impact resistance (results of previous research). A comparison of the commercial alloys revealed no significant differences in impact resistance; however, TiAl4822 was notably superior to TNM alloy in terms of machinability. Moreover, the V-containing ternary alloys demonstrated significantly higher impact resistance than that of TiAl4822, yet they exhibited inferior machinability. Notably, numerous Cr-doped ternary alloys (such as 48.0Al-2.0Cr/2.5Cr) were superior to TiAl4822 in both machinability and impact resistance. Overall, the study findings indicate that a new TiAl alloy for fabricating jet engine turbine blades with significantly reduced cost and improved reliability can be obtained simply by removing Nb from the existing TiAl4822.
Toshimitsu Tetsui (Wed,) studied this question.