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

Abstract

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.

GRAPHICAL ABSTRACT

KEYWORDS:

• TiAl alloy
• Long-period stacking ordering
• Mechanical properties
• Stacking faults

Acknowledgments

The authors are also thankful to the Analytical & Testing Center of Northwestern Polytechnical University for TEM characterization and analysis.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by National Natural Science Foundation of China [grant number 52174377]; Research Fund of the State Key Laboratory of Solidification Processing (NPU), China [grant number 2022-TS-06]; National Key Research and Development Program of China [grant number 2021YFB3702603].