Effects of annealing temperature on microstructures and tensile properties of a single FCC phase CoCuMnNi high-entropy alloy

Dong Geun Kim, Yong Hee Jo, Jeong Min Park, Won Mi Choi, Hyoung Seop Kim, Byeong Joo Lee, Seok S Sohn, Sunghak Lee

Research output: Contribution to journalArticle

Abstract

Copper (Cu) acts as a strong face-centered cubic (FCC) stabilizer as well as an effective element lowering the melting point in FCC-structured high-entropy alloy (HEA) systems. The addition of Cu can reduce the alloy processing temperature; however, there are no studies on the formation of single FCC phase in Cu-added HEAs yet. In this study, a Co10Cu20Mn30Ni40 (at.%) HEA was designed by a thermodynamic calculation using a CALPHAD approach by a software Thermo-Calc 3.0, and effects of annealing temperature on microstructures and room- and cryogenic-temperature tensile properties were investigated. The calculation data showed a very wide region of single FCC phase (532–1073 °C), which was confirmed from the existence of stable single FCC phase at the annealing temperature of 600 °C. The specimen annealed at 600 °C presented the fully-recrystallized FCC phase and the refined grain size of 2.8 μm. As the annealing temperature decreased, thus, the strengths increased while the elongation decreased. In addition, both strength and elongation were improved significantly with decreasing the tensile test temperatures from 298 to 77 K, and the major deformation mechanism was changed from a dislocation slip to a deformation twinning, as confirmed from the specimen annealed at 700 and 900 °C. The present study on grain refinement resulting from the low-temperature annealing would suggest a good method for improving cryogenic mechanical properties of single–FCC–based HEAs.

Original languageEnglish
Article number152111
JournalJournal of Alloys and Compounds
Volume812
DOIs
Publication statusPublished - 2020 Jan 5

Fingerprint

Tensile properties
Entropy
Annealing
Microstructure
Temperature
Cryogenics
Elongation
Grain refinement
Twinning
Dislocations (crystals)
Melting point
Copper
Thermodynamics
Mechanical properties
Processing

Keywords

  • Computational thermodynamic approach
  • Cu addition
  • Grain refinement
  • High-entropy alloy (HEA)
  • Single FCC phase

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

Cite this

Effects of annealing temperature on microstructures and tensile properties of a single FCC phase CoCuMnNi high-entropy alloy. / Kim, Dong Geun; Jo, Yong Hee; Park, Jeong Min; Choi, Won Mi; Kim, Hyoung Seop; Lee, Byeong Joo; Sohn, Seok S; Lee, Sunghak.

In: Journal of Alloys and Compounds, Vol. 812, 152111, 05.01.2020.

Research output: Contribution to journalArticle

Kim, Dong Geun ; Jo, Yong Hee ; Park, Jeong Min ; Choi, Won Mi ; Kim, Hyoung Seop ; Lee, Byeong Joo ; Sohn, Seok S ; Lee, Sunghak. / Effects of annealing temperature on microstructures and tensile properties of a single FCC phase CoCuMnNi high-entropy alloy. In: Journal of Alloys and Compounds. 2020 ; Vol. 812.
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AB - Copper (Cu) acts as a strong face-centered cubic (FCC) stabilizer as well as an effective element lowering the melting point in FCC-structured high-entropy alloy (HEA) systems. The addition of Cu can reduce the alloy processing temperature; however, there are no studies on the formation of single FCC phase in Cu-added HEAs yet. In this study, a Co10Cu20Mn30Ni40 (at.%) HEA was designed by a thermodynamic calculation using a CALPHAD approach by a software Thermo-Calc 3.0, and effects of annealing temperature on microstructures and room- and cryogenic-temperature tensile properties were investigated. The calculation data showed a very wide region of single FCC phase (532–1073 °C), which was confirmed from the existence of stable single FCC phase at the annealing temperature of 600 °C. The specimen annealed at 600 °C presented the fully-recrystallized FCC phase and the refined grain size of 2.8 μm. As the annealing temperature decreased, thus, the strengths increased while the elongation decreased. In addition, both strength and elongation were improved significantly with decreasing the tensile test temperatures from 298 to 77 K, and the major deformation mechanism was changed from a dislocation slip to a deformation twinning, as confirmed from the specimen annealed at 700 and 900 °C. The present study on grain refinement resulting from the low-temperature annealing would suggest a good method for improving cryogenic mechanical properties of single–FCC–based HEAs.

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