Characterisation of L21-ordered Ni2TiAl precipitates in FeMn maraging steels

• Precipitates were identified as L21-ordered Ni2TiAl for the first time.
• The L21-ordered Ni2TiAl phase is coherent and coplanar with the martensite matrix.
• The precipitates remained coherent with the matrix after long-term aging.
• An increase in the Mn content of the alloy led to faster precipitation hardening.

The precipitates formed in a new series of FeMn maraging steels when aged at 500 °C were identified as the L21-ordered Ni2TiAl phase. The precipitate formed a coherent-coplanar microstructure analogously to γ/γ' Ni-based superalloys and maintained a high number density and homogeneous dispersion within α′-martensite matrix even after aging for 10,080 min. An increase in the Mn content of the alloy led to faster precipitation kinetics and thus rapid hardening kinetics.