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    Volume 3, Issue 1 (December 2014)

    Appraisal of Solution Heat Treatment on Elimination of Hafnium Rich γ–γ′ Eutectic and Prior Particle Boundary Precipitate in a Superalloy Powder

    (Received 3 March 2014; accepted 24 June 2014)

    Published Online: 31 December 2014

    CODEN: MPCACD

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    Abstract

    Near-net shape hot isostatic pressing (HIPping) in powder metallurgy (P/M) has been on the increase in the production of superalloys for aero and land based turbine disc applications. A critical challenge related to net-shape HIPping PM is the presence hafnium rich γ–γ′ eutectic in some superalloys powder, which promotes the formation of hafnium oxide. This encourages the formation of prior particle boundary (PPB) precipitates during HIPping, which decreases the bonding strength between powder particles during HIPping and thus becomes the crack initiation and growth sites under loading. Hence, this study aims at dissolving hafnium rich γ–γ′ eutectic in RR1000 superalloy powder and eliminating the PPB precipitates after HIPping by heat treating the powder prior HIPping. As-received powder was heat treated at 900, 1000, 1100, and 1200°C for 2 h, and their microstructure was characterized before the application of pressure for its consolidation. From the outcome of the study, 1200°C was found to be the optimum heat treatment temperature where hafnium rich γ–γ′ eutectic dissolved and where prior particle boundary (PPB) precipitates were eliminated during HIPping for the RR1000 superalloy powder studied.


    Author Information:

    Oluwasegun, K. M.
    Department of Materials Science and Engineering, Obafemi Awolowo Univ.,

    Olawale, J. O.
    Department of Materials Science and Engineering, Obafemi Awolowo Univ.,

    Adeoye, M. O.
    Department of Materials Science and Engineering, Obafemi Awolowo Univ.,

    Olorunniwo, O. E.
    Department of Materials Science and Engineering, Obafemi Awolowo Univ.,

    Ige, O. O.
    Department of Materials Science and Engineering, Obafemi Awolowo Univ.,

    Atanda, P. O.
    Department of Materials Science and Engineering, Obafemi Awolowo Univ.,


    Stock #: MPC20140034

    ISSN:2165-3992

    DOI: 10.1520/MPC20140034

    Author
    Title Appraisal of Solution Heat Treatment on Elimination of Hafnium Rich γ–γ′ Eutectic and Prior Particle Boundary Precipitate in a Superalloy Powder
    Symposium ,
    Committee B09