A high-entropy alloy with dislocation-precipitate skeleton for ultrastrength and ductility

The introduction of dislocations and precipitates has proven to be the effective methods to improve the mechanical properties of metallic materials and break strength-ductility trade-off. However, it is difficult to obtain a suitable combination of both strategies in the metal materials, that is, the coexistence of high-density dislocations and high-volume-fraction precipitates. Here, utilizing a three-dimensional (3D) printing technique, we have successfully achieved a combination of high-density dislocation structures and high-volume-fraction ductile nano-precipitates in a high-entropy alloy (HEA). This 3D-printed HEA, with a novelty dislocation-precipitate skeleton (DPS) architecture and high-density ductile nano precipitations wrapped in the DPS, has an ultra-high tensile strength of 1.8 GPa together with the maximum elongation of 16%. The ultra-high strength mainly comes from dislocation-precipitation synergistic strengthening, while the large ductility mainly originates from an evolution of multiple stacking fault (SF) structures. The DPS can not only slow down the dislocation movement during the strain process without completely hindering its motion, but more importantly, the DPS still has good structural stability during the deformation, which avoids any premature failure due to stress concentrations at the boundary. The DPS formation promotes the development of the metal-based 3D printing technique in the preparation of the high-performance materials, and it can provide an efficient pathway for further enhancement of the alloy properties.(c) 2022 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

In this study, a combination of high-density dislocation structures and high-volume-fraction ductile nano-precipitates was successfully achieved in a high-entropy alloy using a three-dimensional printing technique. The resulting structure, known as the dislocation-precipitate skeleton architecture, demonstrated ultra-high tensile strength and significant ductility, which were attributed to the synergistic strengthening of dislocation-precipitation and the evolution of multiple stacking fault structures.