Microstructure and creep strength of different γ/γ′-strengthened Co-base superalloy variants

The influence of W, Ta, Ti, Nb, V, Si, Mo, Ir and Cr on the high temperature properties of gamma/gamma'-strengthened Co-Al-W superalloys was investigated. All alloys exhibited a gamma/gamma' microstructure with remarkably differing gamma' volume fractions. W, Ta, Ti, Nb and V increased the gamma' volume fraction and gamma' solvus temperature. An increased W content and alloying of additional elements, except Ir, decreased the liquidus temperature. First creep experiments revealed a creep strength comparable with polycrystalline Ni-base superalloys and the importance of grain boundary strengthening. (c) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.