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Title: Investigating the deformation mechanisms of a highly metastable high entropy alloy using in-situ neutron diffraction

Abstract

The present study correlates the effect of enhanced metastability on both the well-understood γ-f.c.c. stacking fault energy (SFE) and deformation mechanisms in the ε-h.c.p. phase of a metastable high entropy alloy (HEA). In this work, the SFE of a Fe40Mn20Cr15Co20Si5 alloy (CS-HEA) was experimentally determined to be ~6.31 mJ m-2 using in-situ neutron diffraction. The relatively low-measured SFE of the CS-HEA results in a high fraction of the ε-h.c.p. phase (58 %) triggering significant stress partitioning to ε-h.c.p. and a marginal fraction of γ-f.c.c. → ε-h.c.p. transformation (~25 %). The ε-h.c.p. phase accommodated a significant amount of strain marked by the large stress-induced decrease of c/a ratio (from ~1.619 to 1.588), which was accompanied by activation of non-basal deformation modes, such as deformation twinning and pyramidal slip. Using in-situ neutron diffraction, we show by decreasing SFE and stabilization of large fractions of ε-h.c.p., activation of non-basal deformation modes are responsible for high work hardenability in absence of significant γ-f.c.c. → ε-h.c.p. transformation.

Authors:
 [1]; ORCiD logo [2];  [1];  [1];  [1]; ORCiD logo [2];  [1]
  1. Univ. of North Texas, Denton, TX (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division
OSTI Identifier:
1649352
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Materials Today Communications
Additional Journal Information:
Journal Volume: 23; Journal Issue: N/A; Journal ID: ISSN 2352-4928
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; High entropy alloy; Stacking fault energy; SFE; Metastable; Martensite; Transformation; Twinning; TRIP; TWIP; Neutron; c/a ratio; c-axis; Deformation mechanism

Citation Formats

Frank, M., Chen, Y., Nene, S. S., Sinha, S., Liu, K., An, Ke, and Mishra, R. S.. Investigating the deformation mechanisms of a highly metastable high entropy alloy using in-situ neutron diffraction. United States: N. p., 2019. Web. https://doi.org/10.1016/j.mtcomm.2019.100858.
Frank, M., Chen, Y., Nene, S. S., Sinha, S., Liu, K., An, Ke, & Mishra, R. S.. Investigating the deformation mechanisms of a highly metastable high entropy alloy using in-situ neutron diffraction. United States. https://doi.org/10.1016/j.mtcomm.2019.100858
Frank, M., Chen, Y., Nene, S. S., Sinha, S., Liu, K., An, Ke, and Mishra, R. S.. Mon . "Investigating the deformation mechanisms of a highly metastable high entropy alloy using in-situ neutron diffraction". United States. https://doi.org/10.1016/j.mtcomm.2019.100858. https://www.osti.gov/servlets/purl/1649352.
@article{osti_1649352,
title = {Investigating the deformation mechanisms of a highly metastable high entropy alloy using in-situ neutron diffraction},
author = {Frank, M. and Chen, Y. and Nene, S. S. and Sinha, S. and Liu, K. and An, Ke and Mishra, R. S.},
abstractNote = {The present study correlates the effect of enhanced metastability on both the well-understood γ-f.c.c. stacking fault energy (SFE) and deformation mechanisms in the ε-h.c.p. phase of a metastable high entropy alloy (HEA). In this work, the SFE of a Fe40Mn20Cr15Co20Si5 alloy (CS-HEA) was experimentally determined to be ~6.31 mJ m-2 using in-situ neutron diffraction. The relatively low-measured SFE of the CS-HEA results in a high fraction of the ε-h.c.p. phase (58 %) triggering significant stress partitioning to ε-h.c.p. and a marginal fraction of γ-f.c.c. → ε-h.c.p. transformation (~25 %). The ε-h.c.p. phase accommodated a significant amount of strain marked by the large stress-induced decrease of c/a ratio (from ~1.619 to 1.588), which was accompanied by activation of non-basal deformation modes, such as deformation twinning and pyramidal slip. Using in-situ neutron diffraction, we show by decreasing SFE and stabilization of large fractions of ε-h.c.p., activation of non-basal deformation modes are responsible for high work hardenability in absence of significant γ-f.c.c. → ε-h.c.p. transformation.},
doi = {10.1016/j.mtcomm.2019.100858},
journal = {Materials Today Communications},
number = N/A,
volume = 23,
place = {United States},
year = {2019},
month = {12}
}

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