Anomalous dislocation response to deformation strain in CrFeCoNiPd high-entropy alloys with nanoscale chemical fluctuations

Nanoscale chemical fluctuations and their effect on the deformation behavior of CrFeCoNi-based high-entropy alloys (HEAs) were investigated using small-angle scattering and in situ neutron diffraction measurements. Small-angle scattering results demonstrated the presence of nano (>10 nm) chemical fluctuations in the as-prepared CrFeCoNiPd HEAs, which was attributed to the negative mixing of enthalpy and the significant atomic radius difference between Pd and the constituent elements in the CrFeCoNi-based alloys. Subsequent tensile tests demonstrated that the yield and tensile strengths of the as-prepared CrFeCoNiPd HEA surpass those of the as-prepared CrMnFeCoNi HEA. Neutron diffraction data analysis revealed an anomalous response of dislocation evolution with the strain, including a more significant linear increase of dislocation density and a greater proportion of screw dislocations in the as-prepared CrFeCoNiPd HEA than in the as-prepared CrMnFeCoNi HEA, which contributed to its enhanced strength. This study paves a new avenue for developing high-performance alloys by modulating chemical fluctuations. © 2024 Acta Materialia Inc.