Strength-ductility synergy and superior strain-hardening ability of Ni38Co25Fe13Cr10Al7Ti7 multi principal element alloy through heterogeneous L12 structure modulation.

In this paper, heterogeneous L1 2 particles were successfully introduced into Ni 38 Co 25 Fe 13 Cr 10 Al 7 Ti 7 MPEA by two-stage aging treatment. Compared with the homogeneous particles, the heterogeneous L1 2 particles strengthened alloy exhibits enhanced strength-plasticity synergy. The tensile elongation is 23.2%, which is higher than all samples with the homogeneous particles, and the yield strength remains at 942 MPa, which is equivalent to the micro particles (972 MPa) with the highest yield strength in the homogeneous particles. Further analysis of the strengthening and deformation mechanisms revealed that precipitation hardening, and heterogeneous deformation-induced hardening were the main factors for the enhanced strength. The deformation-induced layered fracture networks, high-density Lomo-Cottrell locks, and heterogeneous L1 2 particles microstructure characteristics significantly improve the strain hardening ability; GNDs accumulate at the heterogeneous interface to alleviate the stress concentration at the GBs and improve the tensile plasticity of the MPEA with heterogeneous L1 2 particle structure. The heterogeneous L1 2 particle structure obtained through two-stage aging treatment without severe mechanical deformation has attractive engineering application potential. These properties of Ni 38 Co 25 Fe 13 Cr 10 Al 7 Ti 7 MPEA with heterogeneous L1 2 particle structure have important enlightening and practical value. • Designed and prepared Ni 38 Co 25 Fe 13 Cr 10 Al 7 Ti 7 MPEA with heterogeneous L1 2 particles. • Heterogeneous L1 2 particle structure obtained through simple two-stage heat treatment process. • The heterogeneous L1 2 particle reinforced alloy exhibits superior mechanical properties. [ABSTRACT FROM AUTHOR]