An abnormal meta-stable nanoscale eutectic reaction revealed by in-situ observations

Zhou, Lin; Meng, Fanqiang; Zhou, Shihuai; Sun, Kewei; Kim, TaeHoon; Ott, Ryan; Napolitano, Ralph; Kramer, Matthew J.

doi:10.1016/j.actamat.2018.11.027

Title: An abnormal meta-stable nanoscale eutectic reaction revealed by in-situ observations

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Abstract

Phase selection and growth of materials far from equilibrium provides fertile ground for novel phases and morphologies since a multitude of different pathways may be energetically accessible. In this study, a complex metastable devitrification of Al₆₀Sm₁₁ (ε-phase) from its amorphous precursor is discovered using a combination of in-situ high-energy X-ray diffraction (HEXRD), providing insight into the average bulk behavior, and in-situ aberration corrected scanning transmission electron microscopy, revealing the atomic scale mechanisms of growth and their dynamics. We have found that non-equilibrium chemical partitioning disrupts the nominal planer growth by formation of nanoscale Al enriched regions inhomogeneously segregated at the ε/glass interface, to locally balance the compositionally dependent driving force and the associated diffusional burden imposed on its grain growth. These Al-rich regions form fcc-Al-rich nanocrystallites epitaxially with the ε-phase, modifying ε/glass interface mobility and creating a crenulated growth front. As a result, this new mechanism offers a pathway for fabricating alloy structures with nanoprecipitate dispersions through a meta-stable phase transition.

Authors:

Zhou, Lin ^[1];

^[1]; Zhou, Shihuai ^[1]; Sun, Kewei ^[1]; Kim, TaeHoon ^[1]; Ott, Ryan ^[1]; Napolitano, Ralph ^[2]; Kramer, Matthew J. ^[1]

Ames Lab., Ames, IA (United States)
Ames Lab. and Iowa State Univ., Ames, IA (United States)

Publication Date:: Wed Nov 14 00:00:00 EST 2018

Research Org.:: Ames Lab., Ames, IA (United States)

Sponsoring Org.:: USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:: 1483408

Alternate Identifier(s):: OSTI ID: 1636979

Report Number(s):: IS-J-9809
Journal ID: ISSN 1359-6454; PII: S1359645418309030

Grant/Contract Number:: AC02-07CH11358; AC02-06CH11357

Resource Type:: Accepted Manuscript

Journal Name:: Acta Materialia

Additional Journal Information:: Journal Volume: 164; Journal Issue: C; Journal ID: ISSN 1359-6454

Publisher:: Elsevier

Country of Publication:: United States

Language:: English

Subject:: 36 MATERIALS SCIENCE; Metastable phase transition; In situ aberration-corrected transimission electron microscopy; In-situ high-energy X-ray diffraction

Citation Formats


                    Zhou, Lin, Meng, Fanqiang, Zhou, Shihuai, Sun, Kewei, Kim, TaeHoon, Ott, Ryan, Napolitano, Ralph, and Kramer, Matthew J. An abnormal meta-stable nanoscale eutectic reaction revealed by in-situ observations.  United States: N. p., 2018. 
Web.  doi:10.1016/j.actamat.2018.11.027.

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                    Zhou, Lin, Meng, Fanqiang, Zhou, Shihuai, Sun, Kewei, Kim, TaeHoon, Ott, Ryan, Napolitano, Ralph, & Kramer, Matthew J. An abnormal meta-stable nanoscale eutectic reaction revealed by in-situ observations.  United States.  https://doi.org/10.1016/j.actamat.2018.11.027

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                    Zhou, Lin, Meng, Fanqiang, Zhou, Shihuai, Sun, Kewei, Kim, TaeHoon, Ott, Ryan, Napolitano, Ralph, and Kramer, Matthew J. Wed .  
"An abnormal meta-stable nanoscale eutectic reaction revealed by in-situ observations".  United States.  https://doi.org/10.1016/j.actamat.2018.11.027.  https://www.osti.gov/servlets/purl/1483408.

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@article{osti_1483408,

  title        = {An abnormal meta-stable nanoscale eutectic reaction revealed by in-situ observations},

  author       = {Zhou, Lin and Meng, Fanqiang and Zhou, Shihuai and Sun, Kewei and Kim, TaeHoon and Ott, Ryan and Napolitano, Ralph and Kramer, Matthew J.},

  abstractNote = {Phase selection and growth of materials far from equilibrium provides fertile ground for novel phases and morphologies since a multitude of different pathways may be energetically accessible. In this study, a complex metastable devitrification of Al60Sm11 (ε-phase) from its amorphous precursor is discovered using a combination of in-situ high-energy X-ray diffraction (HEXRD), providing insight into the average bulk behavior, and in-situ aberration corrected scanning transmission electron microscopy, revealing the atomic scale mechanisms of growth and their dynamics. We have found that non-equilibrium chemical partitioning disrupts the nominal planer growth by formation of nanoscale Al enriched regions inhomogeneously segregated at the ε/glass interface, to locally balance the compositionally dependent driving force and the associated diffusional burden imposed on its grain growth. These Al-rich regions form fcc-Al-rich nanocrystallites epitaxially with the ε-phase, modifying ε/glass interface mobility and creating a crenulated growth front. As a result, this new mechanism offers a pathway for fabricating alloy structures with nanoprecipitate dispersions through a meta-stable phase transition.},

  doi          = {10.1016/j.actamat.2018.11.027},

  journal      = {Acta Materialia},

  number       = C,

  volume       = 164,

  place        = {United States},

  year         = {Wed Nov 14 00:00:00 EST 2018},

  month        = {Wed Nov 14 00:00:00 EST 2018}

}

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