Abnormal growth of faceted (WC) grains in a (Co) liquid matrix

Park, Y J; Yoon, D Y; Hwang, N M

doi:10.1007/BF02652373

Title: Abnormal growth of faceted (WC) grains in a (Co) liquid matrix

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Abstract

If the grains dispersed in a liquid matrix are spherical, their surface atomic structure is expected to be rough (diffuse), and their coarsening has been observed to be controlled by diffusion in the matrix. They do not, furthermore, undergo abnormal growth. On the other hand, in some compound material systems, the grains in liquid matrices are faceted and often show abnormal coarsening behavior. Their faceted surface planes are expected to be singular (atomically flat) and therefore grow by a defect-assisted process and two-dimensional (2-D) nucleation. Contrary to the usual coarsening theories, their growth velocity is not linearly dependent on the driving force arising from the grain size difference. If the growth of the faceted grains occurs by 2-D nucleation, the rate is expected to increase abruptly at a critical supersaturation, as has been observed in crystal growth in melts and solutions. It is proposed that this growth mechanism leads to the abnormal grain coarsening. The 2-D nucleation theory predicts that there is a threshold initial grain size for the abnormal grain growth (AGG), and the propensity for AGG will increase with the heat-treatment temperature. The AGG behavior will also vary with the defects in the grains. These predictions are qualitativelymore »« less

Authors:

Park, Y J; Yoon, D Y ^[1]; Hwang, N M ^[2]

Korea Advanced Inst. of Science and Technology, Taejeon (Korea, Republic of). Dept. of Materials Science and Engineering
Korea Research Inst. of Standards and Science, Taejeon (Korea, Republic of)

Publication Date:: Sun Sep 01 00:00:00 EDT 1996

Sponsoring Org.:: USDOE

OSTI Identifier:: 382529

Resource Type:: Journal Article

Journal Name:: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science

Additional Journal Information:: Journal Volume: 27; Journal Issue: 9; Other Information: PBD: Sep 1996

Country of Publication:: United States

Language:: English

Subject:: 36 MATERIALS SCIENCE; COMPOSITE MATERIALS; SINTERING; TUNGSTEN CARBIDES; GRAIN GROWTH; COBALT; LIQUID METALS; DIFFUSION; DEFECTS; NUCLEATION; SUPERSATURATION; GRAIN SIZE; TEMPERATURE DEPENDENCE; POWDERS; MILLING

Citation Formats


                    Park, Y J, Yoon, D Y, and Hwang, N M. Abnormal growth of faceted (WC) grains in a (Co) liquid matrix.  United States: N. p., 1996. 
        Web.  doi:10.1007/BF02652373.

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                    Park, Y J, Yoon, D Y, & Hwang, N M. Abnormal growth of faceted (WC) grains in a (Co) liquid matrix.  United States.  https://doi.org/10.1007/BF02652373

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                    Park, Y J, Yoon, D Y, and Hwang, N M. 1996.  
        "Abnormal growth of faceted (WC) grains in a (Co) liquid matrix".  United States.  https://doi.org/10.1007/BF02652373.

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@article{osti_382529,

  title        = {Abnormal growth of faceted (WC) grains in a (Co) liquid matrix},

  author       = {Park, Y J and Yoon, D Y and Hwang, N M},

  abstractNote = {If the grains dispersed in a liquid matrix are spherical, their surface atomic structure is expected to be rough (diffuse), and their coarsening has been observed to be controlled by diffusion in the matrix. They do not, furthermore, undergo abnormal growth. On the other hand, in some compound material systems, the grains in liquid matrices are faceted and often show abnormal coarsening behavior. Their faceted surface planes are expected to be singular (atomically flat) and therefore grow by a defect-assisted process and two-dimensional (2-D) nucleation. Contrary to the usual coarsening theories, their growth velocity is not linearly dependent on the driving force arising from the grain size difference. If the growth of the faceted grains occurs by 2-D nucleation, the rate is expected to increase abruptly at a critical supersaturation, as has been observed in crystal growth in melts and solutions. It is proposed that this growth mechanism leads to the abnormal grain coarsening. The 2-D nucleation theory predicts that there is a threshold initial grain size for the abnormal grain growth (AGG), and the propensity for AGG will increase with the heat-treatment temperature. The AGG behavior will also vary with the defects in the grains. These predictions are qualitatively confirmed in the sintered WC-Co alloy prepared from fine (0.85-{micro}m) and coarse (5.48-{micro}m) WC powders and their mixtures. The observed dependence of the AGG behavior on the sintering temperature and the milling of the WC powder is also qualitatively consistent with the predicted behavior.},

  doi          = {10.1007/BF02652373},

  url          = {https://www.osti.gov/biblio/382529},
  journal      = {Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science},
number       = 9,

  volume       = 27,

  place        = {United States},

  year         = {Sun Sep 01 00:00:00 EDT 1996},

  month        = {Sun Sep 01 00:00:00 EDT 1996}

}

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