: The inherent thermal-mechanical instability of ultrafine-grained Cu alloys has long hampered their application in critical high-temperature environments. This work adopted a hierarchical dispersoid strategy in laser powder bed fusion (LPBF) produced immiscible Cu-316L alloys. Rapid solidification of LPBF (10 3 -10 8 K/s) induces the hierarchical dispersion of micron-submicron γ-Fe, submicron χ and Cr-O amorphous nano-oxide particles in the ultrafine-grained ε-Cu matrix (∼0.74 μm), in-situ constructing high-density immiscible heterointerfaces. The immiscible Cu-316L alloys exhibit exceptional thermal-mechanical stability with only ∼72% grain coarsening, high hardness retention rate of 83%, and high ultimate tensile strength with total ductility of 523 MPa and 20.6% even after annealing at 900 °C (0.86 T m of Cu) for 4 h, outperforming conventional precipitation-strengthened CuCrZr alloys stable up to 600 °C. This notable enhancement stems from the synergistic effects of hierarchical heterostructure: (i) microscale immiscible ε/γ heterostructure accommodates strain between heterointerfaces and introduces hetero-deformation induced strengthening; (ii) submicron-nanoscale dispersoids pin grain boundaries and dislocations; (iii) nanoscale crystalline/amorphous heterointerfaces relieve strain localization through dislocation annihilation and shear band constraints. This work provides a new perspective for designing bulk Cu-based structural components for high-temperature environments.
Xu et al. (Mon,) studied this question.