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Title: Phase stability and kinetics of σ-phase precipitation in CrMnFeCoNi high-entropy alloys

Abstract

Although the phase stability of high-entropy alloys in the Cr-Mn-Fe-Co-Ni system has received considerable attention recently, knowledge of their thermodynamic equilibrium states and precipitation kinetics during high-temperature exposure is limited. In the present study, an off-equiatomic Cr 26Mn 20Fe 20Co 20Ni 14 high-entropy alloy was solutionized and isothermally aged at temperatures between 600 °C and 1000 °C for times to 1000 h. In the original single-phase fcc matrix, an intermetallic σ phase was found to form at all investigated temperatures. Its morphology and composition were determined and the precipitation kinetics analyzed using the Johnson-Mehl-Avrami-Kolmogorov equation and an Arrhenius type law. From these analyses, a time-temperature-transformation diagram (TTT diagram) is constructed for this off-equiatomic alloy. We combine our findings with theories of precipitation kinetics developed for traditional polycrystalline fcc alloys to calculate a TTT diagram for the equiatomic CrMnFeCoNi HEA. The results of our investigation may serve as a guide to predict precipitation kinetics in other complex alloys in the Cr-Mn-Fe-Co-Ni system.

Authors:
ORCiD logo [1];  [1];  [1];  [2];  [1];  [3]
  1. Ruhr Univ., Bochum (Germany). Inst. of Materials
  2. Ruhr Univ., Bochum (Germany). Materials Research Dept. Center for Interface Dominated Materials (ZGH)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ruhr Univ., Bochum (Germany)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); German Research Foundation (DFG)
OSTI Identifier:
1474747
Alternate Identifier(s):
OSTI ID: 1479735
Grant/Contract Number:  
AC05-00OR22725; LA 3607/1-1; GE 2736/1-1
Resource Type:
Published Article
Journal Name:
Acta Materialia
Additional Journal Information:
Journal Volume: 161; Journal ID: ISSN 1359-6454
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; high entropy alloys; CoCrFeMnNi; microstructure; TTT diagram; Johnson–Mehl–Avrami (JMA) equation

Citation Formats

Laplanche, G., Berglund, S., Reinhart, C., Kostka, A., Fox, F., and George, E. P. Phase stability and kinetics of σ-phase precipitation in CrMnFeCoNi high-entropy alloys. United States: N. p., 2018. Web. doi:10.1016/j.actamat.2018.09.040.
Laplanche, G., Berglund, S., Reinhart, C., Kostka, A., Fox, F., & George, E. P. Phase stability and kinetics of σ-phase precipitation in CrMnFeCoNi high-entropy alloys. United States. doi:10.1016/j.actamat.2018.09.040.
Laplanche, G., Berglund, S., Reinhart, C., Kostka, A., Fox, F., and George, E. P. Thu . "Phase stability and kinetics of σ-phase precipitation in CrMnFeCoNi high-entropy alloys". United States. doi:10.1016/j.actamat.2018.09.040.
@article{osti_1474747,
title = {Phase stability and kinetics of σ-phase precipitation in CrMnFeCoNi high-entropy alloys},
author = {Laplanche, G. and Berglund, S. and Reinhart, C. and Kostka, A. and Fox, F. and George, E. P.},
abstractNote = {Although the phase stability of high-entropy alloys in the Cr-Mn-Fe-Co-Ni system has received considerable attention recently, knowledge of their thermodynamic equilibrium states and precipitation kinetics during high-temperature exposure is limited. In the present study, an off-equiatomic Cr26Mn20Fe20Co20Ni14 high-entropy alloy was solutionized and isothermally aged at temperatures between 600 °C and 1000 °C for times to 1000 h. In the original single-phase fcc matrix, an intermetallic σ phase was found to form at all investigated temperatures. Its morphology and composition were determined and the precipitation kinetics analyzed using the Johnson-Mehl-Avrami-Kolmogorov equation and an Arrhenius type law. From these analyses, a time-temperature-transformation diagram (TTT diagram) is constructed for this off-equiatomic alloy. We combine our findings with theories of precipitation kinetics developed for traditional polycrystalline fcc alloys to calculate a TTT diagram for the equiatomic CrMnFeCoNi HEA. The results of our investigation may serve as a guide to predict precipitation kinetics in other complex alloys in the Cr-Mn-Fe-Co-Ni system.},
doi = {10.1016/j.actamat.2018.09.040},
journal = {Acta Materialia},
number = ,
volume = 161,
place = {United States},
year = {2018},
month = {9}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1016/j.actamat.2018.09.040

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