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- Anisotropy (1)
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- Ni-base single crystal superalloys (1)
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The creep anisotropy of the single crystal superalloy LEK 94 deformed in tension along [0 0 1] and [1 1 0] directions at 1293 K and 160 MPa was investigated. Elementary microstructural processes which are responsible for a higher increase in creep rates with strain during [1 1 0] as compared to [0 0 1] tensile loading were identified. [1 1 0] tensile creep is associated with a higher number of γ' phase cutting events, where two dislocations with equal Burgers vectors of type <1 1 0> jointly shear the γ' phase. The resulting <2 2 0>-type superdislocation can move by glide. In contrast, during [0 0 1] tensile loading, two dislocations with different <1 1 0>-type Burgers vectors must combine for γ' phase cutting. The resulting <2 0 0>-type superdislocations can only move by a combination of glide and climb. The evolution of dislocation networks during creep determines the nature of the γ' phase cutting events. The higher [1 1 0] creep rates at strains exceeding 2% result from a combination of a higher number of cutting events (density of mobile dislocations in γ') and a higher superdislocation mobility (<2 2 0> glide) in the γ' phase.