Hot Forging of Spherical Particles with Nanocrystalline Microstructures

Authors

  • Hrishikesh Keshavan,

    1. Department of Materials Science and Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey
    Current affiliation:
    1. GE Global Research, Niskayuna, New York
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  • Anders Petersson,

    1. Department of Materials Science and Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey
    Current affiliation:
    1. Kennametal Inc., Latrobe, Pennsylvania
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  • W. Roger Cannon

    Corresponding author
    • Department of Materials Science and Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey
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  • Supported by the Basic Energy Sciences Division of the Department of Energy Grant Number DE-FG02-O2ER46010.

Author to whom correspondence should be addressed. e-mail: cannon@rutgers.edu

Abstract

An alternate method for fabricating ceramics with fine- or nano- scale microstructures is presented. Powder consisting of 2–25 μm diameter spherical particles (average 16 μm) obtained by plasma melting of spray-dried powder and quenching into water, were hot pressed and hot forged. Three different compositions were studied: eutectic alumina-zirconia, the eutectic composition with 1%Y2O3, and the eutectic composition with borosilicate glass. As-quenched particles (Al2O3–(1%Y2O3)ZrO2) contained both amorphous material and 50–80 nm crystallites. Microstructural development of the Al2O3–(1%Y2O3) ZrO2 was followed from room temperature up to hot pressing/hot forging temperatures. When fully dense after forging at 1350°C, the microstructure contained ZrO2 phases <100 nm in diameter embedded in the Al2O3 matrix. Al2O3 grains had an irregular morphology and were on the scale of ~1 μm diameter. A higher order structure designated as cells, containing a few of these grains, were enclosed by boundaries decorated with ZrO2 particles.

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