Abstract
The high resistance of single crystals of nickel-base superalloys to plastic deformation and their superior strength properties at high temperatures are mainly due to the reinforcing γ´ precipitates. The paper deals with the properties and structures of two superalloys differing in the γ/γ´ morphology. The creep resistance of the <001>, <011> and <111> oriented single crystals of superalloys CMSX-4 and CM186LC was compared on the basis of creep rupture curves, creep deformation curves and accompanying development of microstructures in the temperature interval 750 to 950°C. Further, the effect of notches on creep behaviour and the origin of creep cracks were examined.

Key words
creep, single crystal nickel base superalloys, γ/γ´distribution, notch effect

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