Strength, ductility and zero thermal expansion in multicomponent TRIP-Invar alloys

• A new multi-principal-element alloy achieves an ultralow coefficient of thermal expansion (αl = 1.00 × 10−6 K−1) over 100–400 K alongside exceptional tensile strength (560 MPa) and ductility (53% elongation). • The alloy uniquely combines transformation-induced plasticity (TRIP) and the Invar effect at room temperature, defining a new class of TRIP-Invar alloys. • In situ magnetic analysis shows that ferromagnetic order and spin-state transitions compensate lattice contraction, producing zero thermal expansion behavior. • Deformation-triggered martensitic transformation enhances strain hardening via dislocation multiplication and grain boundary reinforcement, resolving the strength–ductility trade-off.