Effect of primary and secondary precipitates on creep strength of Ni-base superalloy single crystals

Creep and Stress Relaxation Anisotropy of a Single-Crystal Superalloy

“…The h001i direction shows slightly better properties than the h011i direction at 1023 K (750°C) which is in line with previous research claiming that h011i oriented materials show worse creep properties compared to the h001i direction. [24,25] At 1223 K (950°C) the anisotropy is smaller. However, the h011i direction shows slightly better properties compared to the h001i direction.…”

“…Literature often concludes that the h011i direction has worse creep properties compared to the h001i and h111i directions. [22][23][24][25] One explanation for this is the orientation of the rafted c¢-particles. [22] In h011i oriented specimens, the orientation of the rafting is 45 deg from the stress axis while for h001i specimens the rafting is either parallel or perpendicular to the stress axis.…”

“…Other researchers [23] state that the tensile creep properties decrease in the sequence h111i, h001i, h011i while in compression the creep properties decreases in the sequence h001i, h111i, h011i. Kakehi [24,25] showed that the h001i direction has better creep properties compared to the h011i direction. In the same study, it was found that h001i shows better properties in tension than compression during creep at 973 K (700°C) while h011i was stronger in compression than in tension.…”

The Effect of Composition, Misfit, and Heat Treatment on the Primary Creep Behavior of Single Crystal Nickel Base Superalloys PWA 1480 and PWA 1484

“…Among the most common are specimen orientation [1,2,4], the presence of secondary γ' [4,7], lattice misfit [8,9], and alloy composition [4]. Mechanistically, large primary creep strains have been linked to cooperative shearing of γ' precipitates by a<112> dislocation ribbons [2].…”

“…Research into shear band formation in single crystal superalloys, however, has shown that there are factors, besides orientation, involved in shear band formation. For instance, the presence of secondary γ' in the γ matrix channels may enhance shear band formation [7]. Other significant indicators of γ' shear may be lattice misfit and precipitate coherency between the γ matrix and the γ' precipitates [8,9].…”