Effect Factors of Internal Stress and Deformation Mechanism for Single Crystal Nickel-Base Superalloys during Creep

Abstract

By means of the measurement of internal friction stress of dislocation movement during steady state creep stage, and observation of microstructure, an investigation has been made into the effect factors of the internal friction stress of single crystal nickel-base superalloys during creep. Results show that the values of internal friction stress of superalloys are enhanced with the increase of the elements Ta and W concentration. The super-dislocations shearing into the y' phase are supposed to be the deformation mechanism of the superalloy 4 in the period of creep later. The fact that the coarsening y' rafted phase and the finer cubic y' phase are precipitated in the y matrix phase may effectively block the movement of dislocations, and enhance the creep resistance of the alloy, this is a main reason for resulting in the superalloy possessing a longer rupture lifetimes.