Achieving exceptional strength-ductility synergy in a dual-phase high entropy alloy via architected complex microstructures

Abstract

In this work, the exceptional strength-ductility synergy of a dual-phase high entropy alloy (HEA) is achieved by architecting complex microstructures. The HEA rolled at 700 °C shows the yield strength and tensile strength as high as 1580 MPa and 1854 MPa with ductility of ∼18.4%. Different flow stress regions (face-centered cubic (FCC) and body-centered cubic (BCC) phases) divided by complex microstructures lead to strong hetero-deformation-induced strain hardening. The dispersed micro-strain band and the precipitates buffering the dislocation in front of the heterogeneous phase boundary also help to improve the ductility. In addition, utilizing the sensitivity difference between FCC and BCC phases for dislocation accumulation, more dislocations are accumulated in FCC phase to reduce the mechanical incompatibility with BCC phase and fully release the strain hardening ability. The strategy of architecting complex microstructures and selectively modifying phases will be beneficial to the development of high-performance dual-phase alloys.