Self-adaptive dislocation morphing ductilizes a refractory high-entropy alloy across an ultrawide temperature spectrum

Metals usually fracture catastrophically at cryogenic temperatures and soften rapidly at high temperatures. This dilemma arises from the incompatibility of strengthening mechanisms across vast temperature regimes. Here, this work unveils a self-adaptive dislocation morphing mechanism in a model NbTaTi-based refractory high-entropy alloy (RHEA) that enables exceptional strength and ductility from 4 K to 1673 K. At cryogenic temperatures, dislocation kinking coupled with deformation twinning suppresses the ductile-to-brittle transition. At ambient conditions, the sequential activation of edge and screw dislocations sustains work hardening. At elevated temperatures, enhanced dislocation interactions generate jogs, multijunctions, and helical dislocations, promoting superplasticity up to 250%. This intrinsic, temperature-responsive evolution of dislocation modes offers a defect engineering strategy for designing RHEAs capable of enduring extreme environments.