摘要
As newly developed metallic materials, several high-entropy alloys (HEAs) have been fabricated via additive manufacturing (AM) and have been found to exhibit more uniform microstructures and better mechanical properties than their as-cast counterparts. However, current additive-manufactured HEAs are relatively unsatisfactory in terms of strength owing to the inevitable micropores or microcracks that occur during their processing. A significant challenge is to further increase the mechanical properties of single-solid-solution HEAs for AM. In light of this, in the present study, a precipitation-strengthened Ni 2.1 CoCrFeNb 0.2 HEA was designed that is particularly easy to print for use in AM. Bulk samples without observed defects were successfully produced by direct laser deposition. The as-deposited Ni 2.1 CoCrFeNb 0.2 HEA showed an excellent strength-ductility combination. After proper heat-treatments, the tensile strength increased dramatically to ∼ 1127 MPa with a tensile elongation of ∼ 17 %, which is the best performance in the reported AM-fabricated HEAs. The precipitation of the γ″ phase was quantitatively analyzed to reveal the excellent strengthening effect in this new AM-fabricated HEA. In the present study, a superior precipitation-reinforced HEA with fully dense microstructures was successfully developed for AM. These results open up new possibilities for the further development of AM-fabricated HEAs.