Tensile deformation behavior and deformation twinning of an equimolar CoCrFeMnNi high-entropy alloy

Soo Joo, Hidemi Kato, M. J. Jang, J. Moon, C. W. Tsai, J. W. Yeh, H. S. Kim

Research output: Contribution to journalArticle

61 Citations (Scopus)

Abstract

The tensile deformation and strain hardening behaviors of an equimolar CoCrFeMnNi high-entropy alloy (HEA) were investigated and compared with low and medium entropy equiatomic alloys (LEA and MEA). The HEA had a lower yield strength than the MEA because the addition of Mn weakens solid solution hardening in the HEA. However, deformation twinning induced the multiple stage strain hardening behavior of the HEA and enhanced strength and elongation. Using tensile-interrupted electron backscatter diffraction analysis, geometrically necessary dislocations were observed as plume-shaped features in grain interior, and a considerable texture was characterized, which is typical of face centered cubic metals. Moreover, the relationship between favorably oriented grains and twinning in the HEA bore a clear resemblance to the same tendency in TWIP steels. The thickness of the twin bundles was less than 100 nm. A high density of stacking defects was found in the nanotwins. Nano twinning and stacking faults were found to contribute to the remarkable mechanical properties. Deformation induced twinning not only demonstrated the dynamic Hall-Petch effect but also changed dislocation cell substructures into microband structures.

Original languageEnglish
Pages (from-to)122-133
Number of pages12
JournalMaterials Science and Engineering A
Volume689
DOIs
Publication statusPublished - 2017 Mar 24

Keywords

  • EBSD
  • High-entropy alloy
  • Stacking fault
  • Strain hardening
  • Twinning

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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