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°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. IMPACT STATEMENT The development of multiple nanometer-sized LOPS bands during deformation in nanolamellar TiAl alloys can significantly improve ductility without resulting in a reduction of yield strength.