Competitive strengthening between dislocation slip and twinning in cast-wrought and additively manufactured CrCoNi medium entropy alloys

W. Woo; Y. S. Kim; H. B. Chae; S. Y. Lee; J. S. Jeong; C. M. Lee; J. W. Won; Y. S. Na; T. Kawasaki; S. Harjo; K. An

doi:10.1016/j.actamat.2023.118699

Competitive strengthening between dislocation slip and twinning in cast-wrought and additively manufactured CrCoNi medium entropy alloys

W. Woo, Y. S. Kim, H. B. Chae, S. Y. Lee, J. S. Jeong, C. M. Lee, J. W. Won, Y. S. Na, T. Kawasaki, S. Harjo, K. An

Materials Engineering

Research output: Contribution to journal › Article › peer-review

38 Scopus citations

Abstract

In situ neutron diffraction experiments have been performed under loading in cast-wrought (CW) and additively manufactured (AM) equiatomic CoCrNi medium-entropy alloys. The diffraction line profile analysis correlated the faulting-embedded crystal structure to the dislocation density, stacking/twin fault probability, and stacking fault energy as a function of strain. The results showed the initial dislocation density of 1.8 × 10¹³ m⁻² in CW and 1.3 × 10¹⁴ m⁻² in AM. It significantly increased up to 1.3 × 10¹⁵ m⁻² in CW and 1.7 × 10¹⁵ m⁻² in AM near fracture. The dislocation density contributed to the flow stress of 470 MPa in CW and 600 MPa in AM, respectively. Meanwhile, the twin fault probability of CW (2.7%) was about two times higher than AM (1.3%) and the stacking fault probability showed the similar tendency. The twinning provided strengthening of 360 MPa in CW and 180 MPa in AM. Such a favorable strengthening via deformation twinning in CW and dislocation slip in AM was attributed to the stacking fault energy. It was estimated as 18.6 mJ/m² in CW and 37.5 mJ/m² in AM by the strain field of dislocations incorporated model. Dense dislocations, deformation twinning, and atomic-scale stacking structure were examined by using electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM).

Original language	English
Article number	118699
Journal	Acta Materialia
Volume	246
DOIs	https://doi.org/10.1016/j.actamat.2023.118699
State	Published - Mar 1 2023

Funding

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (No. NRF-2017M2A2A6A05017653), partly by JSPS Kakenhi 19H05180, and J-PARC beamtime proposal of 2017B0267. A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. YSK and SYL were supported by a National Research Foundation (NRF) grant funded by the Korean government (2021R1A4A1031494). This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (No. NRF-2017M2A2A6A05017653 ), partly by JSPS Kakenhi 19H05180, and J-PARC beamtime proposal of 2017B0267. A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. YSK and SYL were supported by a National Research Foundation (NRF) grant funded by the Korean government ( 2021R1A4A1031494 ).

Funders	Funder number
Korean government	2021R1A4A1031494
Office of Science
Oak Ridge National Laboratory
Japan Society for the Promotion of Science	19H05180, 2017B0267
National Research Foundation of Korea	NRF-2017M2A2A6A05017653

Keywords

CoCrNi medium-entropy alloy
Dislocation density
Neutron diffraction
Strengthening
Twinning

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10.1016/j.actamat.2023.118699

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@article{1469d1f211f54efbaaa8dc456c21b626,

title = "Competitive strengthening between dislocation slip and twinning in cast-wrought and additively manufactured CrCoNi medium entropy alloys",

abstract = "In situ neutron diffraction experiments have been performed under loading in cast-wrought (CW) and additively manufactured (AM) equiatomic CoCrNi medium-entropy alloys. The diffraction line profile analysis correlated the faulting-embedded crystal structure to the dislocation density, stacking/twin fault probability, and stacking fault energy as a function of strain. The results showed the initial dislocation density of 1.8 × 1013 m−2 in CW and 1.3 × 1014 m−2 in AM. It significantly increased up to 1.3 × 1015 m−2 in CW and 1.7 × 1015 m−2 in AM near fracture. The dislocation density contributed to the flow stress of 470 MPa in CW and 600 MPa in AM, respectively. Meanwhile, the twin fault probability of CW (2.7%) was about two times higher than AM (1.3%) and the stacking fault probability showed the similar tendency. The twinning provided strengthening of 360 MPa in CW and 180 MPa in AM. Such a favorable strengthening via deformation twinning in CW and dislocation slip in AM was attributed to the stacking fault energy. It was estimated as 18.6 mJ/m2 in CW and 37.5 mJ/m2 in AM by the strain field of dislocations incorporated model. Dense dislocations, deformation twinning, and atomic-scale stacking structure were examined by using electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM).",

keywords = "CoCrNi medium-entropy alloy, Dislocation density, Neutron diffraction, Strengthening, Twinning",

author = "W. Woo and Kim, {Y. S.} and Chae, {H. B.} and Lee, {S. Y.} and Jeong, {J. S.} and Lee, {C. M.} and Won, {J. W.} and Na, {Y. S.} and T. Kawasaki and S. Harjo and K. An",

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year = "2023",

month = mar,

day = "1",

doi = "10.1016/j.actamat.2023.118699",

language = "English",

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T1 - Competitive strengthening between dislocation slip and twinning in cast-wrought and additively manufactured CrCoNi medium entropy alloys

AU - Woo, W.

AU - Kim, Y. S.

AU - Chae, H. B.

AU - Lee, S. Y.

AU - Jeong, J. S.

AU - Lee, C. M.

AU - Won, J. W.

AU - Na, Y. S.

AU - Kawasaki, T.

AU - Harjo, S.

AU - An, K.

PY - 2023/3/1

Y1 - 2023/3/1

N2 - In situ neutron diffraction experiments have been performed under loading in cast-wrought (CW) and additively manufactured (AM) equiatomic CoCrNi medium-entropy alloys. The diffraction line profile analysis correlated the faulting-embedded crystal structure to the dislocation density, stacking/twin fault probability, and stacking fault energy as a function of strain. The results showed the initial dislocation density of 1.8 × 1013 m−2 in CW and 1.3 × 1014 m−2 in AM. It significantly increased up to 1.3 × 1015 m−2 in CW and 1.7 × 1015 m−2 in AM near fracture. The dislocation density contributed to the flow stress of 470 MPa in CW and 600 MPa in AM, respectively. Meanwhile, the twin fault probability of CW (2.7%) was about two times higher than AM (1.3%) and the stacking fault probability showed the similar tendency. The twinning provided strengthening of 360 MPa in CW and 180 MPa in AM. Such a favorable strengthening via deformation twinning in CW and dislocation slip in AM was attributed to the stacking fault energy. It was estimated as 18.6 mJ/m2 in CW and 37.5 mJ/m2 in AM by the strain field of dislocations incorporated model. Dense dislocations, deformation twinning, and atomic-scale stacking structure were examined by using electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM).

AB - In situ neutron diffraction experiments have been performed under loading in cast-wrought (CW) and additively manufactured (AM) equiatomic CoCrNi medium-entropy alloys. The diffraction line profile analysis correlated the faulting-embedded crystal structure to the dislocation density, stacking/twin fault probability, and stacking fault energy as a function of strain. The results showed the initial dislocation density of 1.8 × 1013 m−2 in CW and 1.3 × 1014 m−2 in AM. It significantly increased up to 1.3 × 1015 m−2 in CW and 1.7 × 1015 m−2 in AM near fracture. The dislocation density contributed to the flow stress of 470 MPa in CW and 600 MPa in AM, respectively. Meanwhile, the twin fault probability of CW (2.7%) was about two times higher than AM (1.3%) and the stacking fault probability showed the similar tendency. The twinning provided strengthening of 360 MPa in CW and 180 MPa in AM. Such a favorable strengthening via deformation twinning in CW and dislocation slip in AM was attributed to the stacking fault energy. It was estimated as 18.6 mJ/m2 in CW and 37.5 mJ/m2 in AM by the strain field of dislocations incorporated model. Dense dislocations, deformation twinning, and atomic-scale stacking structure were examined by using electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM).

KW - CoCrNi medium-entropy alloy

KW - Dislocation density

KW - Neutron diffraction

KW - Strengthening

KW - Twinning

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DO - 10.1016/j.actamat.2023.118699

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SN - 1359-6454

VL - 246

JO - Acta Materialia

JF - Acta Materialia

M1 - 118699

ER -

Competitive strengthening between dislocation slip and twinning in cast-wrought and additively manufactured CrCoNi medium entropy alloys

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