Grain-selective growth makes Al0.1CoCrFeNi high entropy alloys strong and ultra-ductile

Abstract

The trade-off between strength and ductility of structural materials has always been a concern, and the pursuit of higher strength often comes with the inevitable sacrifice of ductility, which poses challenges for the design and manufacture of high-performance engineering materials. In this study, we introduce a novel concept called grain-selective growth (GSG) to address the strength-ductility trade-off by effectively triggering the strain hardening capacity of the single-phase FCC HEAs. Specifically, we prepared an Al0.1CoCrFeNi high-entropy alloy with a heterogeneous grain structure using cyclic rolling and annealing. By employing this approach, our GSG HEA achieves an ultra-ductility with ∼53% uniform elongation and an ultimate tensile strength of 1165 MPa. Rapidly accumulating geometrically necessary dislocations in the domain boundary region, as revealed through electron backscatter diffraction analysis, have led to the development of high-level heterogeneous deformation-induced (HDI) stress. In addition, we also observed synergistic strain hardening effects generated by various deformation mechanisms, such as dislocation pile-ups, stacking faults (SFs), deformation twinning, dislocation walls, and SF networks. This study provides valuable insights for the manufacturing of high-performance heterostructure materials, making it possible to develop advanced alloys with higher strength and ductility, suitable for a wide range of engineering applications.