J. Van Sluytman, A. Suzuki, T. M. Pollock, University of Michigan, Ann Arbor, MI
Ni-based superalloys modified with platinum group metal (PGM) additions of Pt and/or Ir with selective amounts of Al, Cr, Re, Ta, and Hf have been investigated. TEM evaluations reveal two-phase gamma-gamma prime microstructures over a wide range of composition with Pt and/or Ir additions up to 5at%. Precipitate morphologies range from cuboidal to irregularly shaped, indicative of a wide range of lattice misfit. All PGM modified alloys possess positive misfit with magnitudes ranging from 0.3-1.0%. Beyond the PGM additions, Cr, Re, and Ta have the greatest influence on precipitate morphology. Compression creep tests were carried out in the stress range of 50-90 MPa at 1000°C. Creep tests indicate that alloys containing (in at.%) 2.5% Pt or a combination of 2.5%Pt-2.5%Ir have higher resistance to creep deformation compared to alloys with 5%Pt or alloys containing only Ir.
Summary: Ni-based superalloys modified with platinum group metal (PGM) additions of Pt and/or Ir with selective amounts of Al, Cr, Re, Ta, and Hf have been investigated. Creep tests indicate that alloys containing (in at.%) 2.5% Pt or a combination of 2.5%Pt-2.5%Ir have higher resistance to creep deformation compared to alloys with 5%Pt or alloys containing only Ir.
