Ductile B2 Intermetallics-Driven Strength-Ductility Synergy in Heterolaminated Multi-Principal Element Alloys

Conventional intermetallic-strengthened alloys invariably suffer from a strength-ductility trade-off, as brittle η, σ, and µ phases precipitate at interfaces and trigger premature failure. Here, we overturn this paradigm in a multi-principal element alloy (MPEA) by deliberately engineering its B2 intermetallic phase to act not as a crack-initiator, but as a ductile, load-bearing constituent. Through intrinsic phase toughening enabled by multicomponent chemical complexity, pre-existing dislocations, and local compositional fluctuations, we demonstrate that the B2 phase can sustain continuous dislocation glide and multiplication. Simultaneously, we impose a heterogeneous laminated architecture of face-centered cubic (FCC) and B2 domains, which promotes strain delocalization and redistributes stress to suppress interface cracking. The resulting synergy culminates in an exceptional combination of mechanical properties at room temperature: a yield strength of 1.24 GPa, an ultimate tensile strength of 1.57 GPa, and 20% uniform elongation, along with a high strain hardening rate exceeding 3 GPa across a wide strain range. These findings establish a new design strategy through integrating ductile intermetallic phases with mesoscale heterogeneity to overcome the long-standing strength-ductility trade-off in structural materials.