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

Frank, M.; Chen, Y.; Nene, S. S.; Sinha, S.; Liu, K.; An, Ke; Mishra, R. S.

doi:10.1016/j.mtcomm.2019.100858

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

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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:

Frank, M. ^[1];

^[2]; Nene, S. S. ^[1]; Sinha, S. ^[1]; Liu, K. ^[1];

^[2]; Mishra, R. S. ^[1]

Univ. of North Texas, Denton, TX (United States)
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Publication Date:: Mon Dec 23 00:00:00 EST 2019

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.  doi:10.1016/j.mtcomm.2019.100858.

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                    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

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                    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.

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@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         = {Mon Dec 23 00:00:00 EST 2019},

  month        = {Mon Dec 23 00:00:00 EST 2019}

}

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