Turning Intermediate‐Temperature Brittleness Into Strength‐Ductility Synergy in Refractory Complex Concentrated Alloys via Nanoscale Heterogeneity Engineering

Refractory complex‐concentrated alloys (RCCAs) show exceptional promise for extreme‐environment applications, yet intermediate‐temperature instability (0.4–0.6 T m ) and plasticity degradation severely constrain their development. This work provides an effective strategy to transform the inherent intermediate‐temperature instability into a performance advantage by implementing a coordinated design of a metastable Ti 2 ZrTa 0.75 composition and targeted annealing temperatures, thereby creating synergistic nanoscale heterogeneity. Multi‐scale structural characterization and molecular dynamic simulations reveal that tailored annealing at 900°C–1000°C generates two key synergistic heterogeneities: (1) nanoscale Ta‐rich clusters (∼40 nm) and (2) spinodal decomposition wavelengths of 4.5–8.2 nm. These features orchestrate a competitive‐cooperative interaction between dislocation glide, reversible martensitic transformation, and hierarchical twinning. Depending on the annealing temperature, the dominant deformation mechanism shifts, leading to either martensite‐assisted hardening (900°C annealing, 271 MPa hardening strength) or twin‐dominated plasticity (1000°C annealing, 19.2% uniform elongation). This study overturns the conventional avoidance of instability, presenting a novel paradigm for unlocking high ductility in RCCAs via simple thermal processing.