Creep Behavior and Damage of Ni-Base Superalloys PM 1000 and PM 3030

Two oxide dispersion strengthening (ODS) nickel-base superalloys, a solely dispersion-strengthened alloy (PM 1000) and an additionally gamma'-strengthened alloy (PM 3030) are investigated regarding creep resistance at temperatures between 600 degrees C and 1000 degrees C. The creep strength advantage of PM 3030 over PM 1000 decreases as the temperature increases due to the thermal instability of the gamma' phase. The particle strengthening contribution in both alloys increases linearly with load. However, solid solution softening leads to an apparent drop in particle strengthening in PM 1000. Deformation concentration in slip bands is more accentuated in PM 3030-R34 due to additional gamma' strengthening combined with strongly textured coarse and elongated grain structure. Finer, equiaxed grains reduce creep strength at higher temperatures due to grain boundary deformation processes and premature pore formation, but have only minor impact at low and intermediate temperatures.