Long-period stacking ordering induced ductility of nanolamellar TiAl alloy at elevated temperature

This work reports that the plastic deformation mechanism of lamellar microstructure (LM) in Ti-43.5Al-4Nb-1Mo-0.1B (TNM) alloy transforms from stacking faults (SFs)-dominated process to long-period stacking ordering (LPSO) structures-mediated process with a slight increase in lamellar spacing (LS) (20-36 nm). Multiple LPSO bands significantly enhance the work hardening response and trigger the transformation-induced plasticity (TRIP) effect, causing a four-fold higher ductility than SF-deformed LM at 750 & DEG;C without compromising yield strength (YS). This phenomenon provides novel insights into the development of high-performance TiAl alloys with extremely nano-LM (LS < 55 nm) at elevated temperatures.

Automated summary

This study reveals that the plastic deformation mechanism of lamellar microstructure in TNM alloy changes from stacking faults to long-period stacking ordering with a slight increase in lamellar spacing. Multiple LPSO bands significantly enhance the work hardening response and trigger the TRIP effect, resulting in four times higher ductility than SF-deformed LM at 750°C without compromising yield strength. This finding provides novel insights into the development of high-performance TiAl alloys with extremely nano-LM at elevated temperatures.