Tough and creep-resistant NiTi-based medium-to-high entropy intermetallic compounds

• New NiTi-based medium and high-entropy B2 intermetallic compounds developed. • MEIC and HEIC show ∼ 20% room-temperature plasticity and ∼ 1.5 GPa strength. • Creep resistance at 850-950°C is comparable to commercial TiAl alloys • Solute-drag creep mechanism identified with n ≈3 and Q ≈300–340 kJ/mol. • High entropy effect promotes strain homogeneity and reduces anisotropy. Overcoming the inherent room-temperature brittleness of intermetallic compounds while retaining their high-temperature strength is crucial for developing materials suited for extreme environments. Here, we demonstrate a medium- to high-entropy design strategy applied to NiTi-based B2 intermetallic compounds, achieving an unprecedented combination of mechanical properties. Single-phase 4C (NiCo-TiHf) and 5C (NiCo-TiZrHf) alloys exhibit remarkable room-temperature compressive plasticity (∼20% strain) coupled with high yield strengths (∼1.5 GPa). Notably, the 4C and 6C 1 (NiCoFe 6 -TiZrHf) alloys demonstrate outstanding creep resistance between 850°C and 950°C, comparable to that of commercial TiAl and refractory high-entropy alloys, governed by a solute-drag controlled dislocation creep mechanism (n ≈ 3, Q ≈ 300–340 kJ/mol). Crystal plasticity analysis reveals that increased configurational entropy promotes homogeneous strain distribution, while precipitates dictate plastic anisotropy. This work provides a new pathway to alleviate the strength-ductility trade-off in B2 intermetallics, facilitating the design of tough and creep-resistant materials for demanding high-temperature applications.