Hierarchically heterogeneous microstructure enables ultrahigh-strength and good ductility in selective laser melted eutectic high-entropy alloys

Abstract

Achieving favorable strength-ductility synergy has long been one of the main challenges for developing structural materials. The current work reports a selective laser melted eutectic high-entropy alloy with ultrahigh-strength (yield strength 1446 MPa, ultimate tensile strength 1737 MPa) and good ductility (elongation 11%), achieved by tuning the hierarchically heterogeneous microstructures from micro-to nano-scale. Both of nano-sized B2 and L12 phases effectively hinder the dislocation motion and thus significantly improve the strengths. The cellular face-centered cubic matrix ensures the uniform deformation of the alloy, and the possible brittle failure of the hard B2 phase is alleviated by Cr-rich clusters.

Keywords

• Strength-ductile synergy
• Eutectic high-entropy alloy
• Selective laser melting
• Hierarchically heterogeneous microstructures
• Dislocation motion