An excellent combination of strength and ductility via hierarchical precipitation structures in Co-free medium-entropy alloys

• DOI: 10.1016/j.jmrt.2024.07.104
• Publication Date: 2024-07-18T19:40:18Z
• Authors: Jiaxin Zhang; Shengguo Ma; Xiaoxiao Liu; Junwei Qiao; Jianjun Wang; Dan Zhao; Zhiming Jiao; Tuanwei Zhang; Bin Xu; Zhihua Wang
• Keywords: Precipitation hardening; Ductility (Earth science); Work hardening; Stacking fault; High-Entropy Alloys; Solid solution strengthening

A Co-free non-equiatomic Ni2·5CrFeAl0·25Ti0.25 medium-entropy alloy (MEA) with an excellent strength-ductility synergy was fabricated, which shows a multiphase structure composed of face-centered cubic (FCC), L12 (ordered FCC), and Cr-rich body-centered (BCC) phase by thermomechanical processing. Specifically, the aged sample displays outstanding yield tensile strength (YTS, ∼1188 MPa), ultimate (UTS, ∼1560 MPa) work-hardening rate (WHR, ∼4.5 GPa) values as well acceptable plasticity ∼16.6%. Theoretical calculations suggest that precipitation strengthening significantly contributes to achieving fascinating among various contributors. Further analyses reveal multiple nanoscale stacking-fault (SF) networks are activated during plastic deformation in alloy. Accordingly, dual effects consisting hierarchical SF lead combination strain-hardening capacity.