Abstract
The correlation between the direction of rafted γ' plates and the orientation of crystal grains in a polycrystalline nickel-based Superalloy, IN-100, was investigated through the microstructural observation of creep ruptured and creep interrupted specimens at 1273K, 98-216 MPa. TEM observation showed that the rafted γ' plates formed as parallel to the {001} plane independent the orientation of crystal grains. The aspect ratio of γ' phase was measured in many grains with different orientations. The rate of rafting was supposed to decrease with increasing the orientation between the stress axis and the [001] direction of the grain, θ. The time at which the aspect ratio reaches to the maximum value becomes longer with decreasing the stress applied on {001} plane. Consequently, it was confirmed that the formation of rafted γ' is not only defined by the creep testing time.
