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Title: Suppressing η-phase development in steel-cemented tungsten carbide: A spark plasma sintering study

We describe the phase stability of a cemented tungsten carbide prepared using a high-vanadium tool steel as the cementing/binder phase and confirm suppression of (Fe, W) 6C η-phase formation, attributed to the preferential formation of a V 0.78W 0.22C 1-x phase that exists as islands within the Fe-rich binder matrix. The samples were prepared using spark plasma sintering (SPS), starting from commercially available WC and A11-LVC tool steel powders. The starting powders were ball milled adding 10, 15, and 20 vol.% steel. An A11-LVC tool steel was chosen as a low-cost hard steel (49 HRC) that does not contain Ni or Co but has a high vanadium (~9 wt.%) and carbon (~1.75 wt.%) content. Our results show that sintering by SPS can produce high-density (>98%) WC-steel specimens in which the matrix wets the WC grain surfaces and formation of the brittle η-phase is avoided. The η phase is often regarded as embrittling and undesirable, and its presence can result in degradation of mechanical properties. Microhardness values for the WC-10 and WC-15 vol.% steel samples were 12.3 ± 1.2 and 13.0 ± 0.9 GPa, respectively, whereas the fracture toughness values were 8.83 ± 0.48 and 8.81 ± 0.61 MPa·m 1/2, respectively.
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [2] ; ORCiD logo [1]
  1. Univ. of California, San Diego, CA (United States). Dept. of Mechanical and Aerospace Engineering; Alfred Univ., NY (United States). Kazuo Inamori School of Engineering
  2. Univ. of California, San Diego, CA (United States). Dept. of Mechanical and Aerospace Engineering
  3. Advanced Materials and Devices, Inc., Reno, NV (United States)
Publication Date:
Report Number(s):
LLNL-JRNL-751653
Journal ID: ISSN 0002-7820; 937352
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Journal of the American Ceramic Society
Additional Journal Information:
Journal Volume: 102; Journal Issue: 2; Journal ID: ISSN 0002-7820
Publisher:
American Ceramic Society
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Tungsten/tungsten compounds; carbides; spark plasma sintering
OSTI Identifier:
1488769

Cahill, James T., Kelly, James P., Novitskaya, Ekaterina, McKee, Michael, Bahena, Joel A., and Graeve, Olivia A.. Suppressing η-phase development in steel-cemented tungsten carbide: A spark plasma sintering study. United States: N. p., Web. doi:10.1111/jace.15814.
Cahill, James T., Kelly, James P., Novitskaya, Ekaterina, McKee, Michael, Bahena, Joel A., & Graeve, Olivia A.. Suppressing η-phase development in steel-cemented tungsten carbide: A spark plasma sintering study. United States. doi:10.1111/jace.15814.
Cahill, James T., Kelly, James P., Novitskaya, Ekaterina, McKee, Michael, Bahena, Joel A., and Graeve, Olivia A.. 2018. "Suppressing η-phase development in steel-cemented tungsten carbide: A spark plasma sintering study". United States. doi:10.1111/jace.15814.
@article{osti_1488769,
title = {Suppressing η-phase development in steel-cemented tungsten carbide: A spark plasma sintering study},
author = {Cahill, James T. and Kelly, James P. and Novitskaya, Ekaterina and McKee, Michael and Bahena, Joel A. and Graeve, Olivia A.},
abstractNote = {We describe the phase stability of a cemented tungsten carbide prepared using a high-vanadium tool steel as the cementing/binder phase and confirm suppression of (Fe, W)6C η-phase formation, attributed to the preferential formation of a V0.78W0.22C1-x phase that exists as islands within the Fe-rich binder matrix. The samples were prepared using spark plasma sintering (SPS), starting from commercially available WC and A11-LVC tool steel powders. The starting powders were ball milled adding 10, 15, and 20 vol.% steel. An A11-LVC tool steel was chosen as a low-cost hard steel (49 HRC) that does not contain Ni or Co but has a high vanadium (~9 wt.%) and carbon (~1.75 wt.%) content. Our results show that sintering by SPS can produce high-density (>98%) WC-steel specimens in which the matrix wets the WC grain surfaces and formation of the brittle η-phase is avoided. The η phase is often regarded as embrittling and undesirable, and its presence can result in degradation of mechanical properties. Microhardness values for the WC-10 and WC-15 vol.% steel samples were 12.3 ± 1.2 and 13.0 ± 0.9 GPa, respectively, whereas the fracture toughness values were 8.83 ± 0.48 and 8.81 ± 0.61 MPa·m1/2, respectively.},
doi = {10.1111/jace.15814},
journal = {Journal of the American Ceramic Society},
number = 2,
volume = 102,
place = {United States},
year = {2018},
month = {6}
}

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