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

Area of Science:

• Materials Science
• Metallurgy
• Mechanical Engineering

Background:

• Conventional intermetallic-strengthened alloys face a strength-ductility trade-off due to brittle phase precipitation.
• Brittle phases (η, σ, µ) at interfaces initiate cracks and cause premature failure in traditional alloys.

Purpose of the Study:

• To engineer a multi-principal element alloy (MPEA) where the B2 intermetallic phase acts as a ductile, load-bearing constituent, not a crack initiator.
• To overcome the inherent strength-ductility trade-off in structural materials.

Main Methods:

• Deliberate engineering of the B2 intermetallic phase for intrinsic phase toughening via multicomponent chemical complexity, dislocations, and compositional fluctuations.
• Imposing a heterogeneous laminated architecture of face-centered cubic (FCC) and B2 domains to promote strain delocalization and suppress interface cracking.

Main Results:

• Demonstrated that the engineered B2 phase sustains dislocation glide and multiplication, acting as a ductile component.
• Achieved a yield strength of 1.24 GPa, ultimate tensile strength of 1.57 GPa, and 20% uniform elongation at room temperature.
• Observed a high strain hardening rate exceeding 3 GPa over a wide strain range.

Conclusions:

• Established a new design strategy by integrating ductile intermetallic phases with mesoscale heterogeneity.
• Successfully overcame the long-standing strength-ductility trade-off in structural materials through this novel approach.