Microstructural Evolution and Mechanical Properties of Non-Equiatomic (CoNi)74.66Cr17Fe8C0.34 High-Entropy Alloy

You Sub Kim, Hobyung Chae, E. Wen Huang, Jayant Jain, Stefanus Harjo, Takuro Kawasaki, Sun Ig Hong*, Soo Yeol Lee

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

In this study, we manufactured a non-equiatomic (CoNi)74.66Cr17Fe8C0.34 high-entropy alloy (HEA) consisting of a single-phase face-centered-cubic structure. We applied in situ neutron diffraction coupled with electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM) to investigate its tensile properties, microstructural evolution, lattice strains and texture development, and the stacking fault energy. The non-equiatomic (CoNi)74.66Cr17Fe8C0.34 HEA revealed a good combination of strength and ductility in mechanical properties compared to the equiatomic CoNiCrFe HEA, due to both stable solid solution and precipitation-strengthened effects. The non-equiatomic stoichiometry resulted in not only a lower electronegativity mismatch, indicating a more stable state of solid solution, but also a higher stacking fault energy (SFE, ~50 mJ/m2 ) due to the higher amount of Ni and the lower amount of Cr. This higher SFE led to a more active motion of dislocations relative to mechanical twinning, resulting in severe lattice distortion near the grain boundaries and dislocation entanglement near the twin boundaries. The abrupt increase in the strain hardening rate (SHR) at the 1~3% strain during tensile deformation might be attributed to the unusual stress triaxiality in the {200} grain family. The current findings provide new perspectives for designing non-equiatomic HEAs.

Original languageEnglish
Article number1312
JournalMaterials
Volume15
Issue number4
DOIs
StatePublished - 1 Feb 2022

Keywords

  • High-entropy alloy
  • Mechanical property
  • Neutron diffraction
  • Stacking fault energy

Fingerprint

Dive into the research topics of 'Microstructural Evolution and Mechanical Properties of Non-Equiatomic (CoNi)74.66Cr17Fe8C0.34 High-Entropy Alloy'. Together they form a unique fingerprint.

Cite this