Abstract
Creep tests of nickel superalloy single crystals were performed at 850 °C and 950 °C with the aim to determine the effect of crystal orientation on the creep resistance. At 950 °C and stress of 250 MPa the orientation <111> exhibits the highest resistance against the tensile creep, while the orientation <001> exhibits the highest resistance against the compressive creep. At 850 °C the orientation <001> resists better the tensile creep than the orientation <111> in the region of higher stresses; this sequence is reversed in the region of lower stresses. The observed changes of the dislocation and precipitation structure due to high temperature creep are in agreement with the model of deformation process taking place predominantly in the γ channels and only to a minor extent in the γ' particles.

Key words
creep behaviour, compressive creep, the model of deformation process

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