Abstract Nickel-base superalloys are used extensively in the hot regions of gas turbines, because they have excellent mechanical properties at high temperature. The morphologies and sizes of γ’ precipitates have strong effects on the creep properties of the alloys. In this paper, a crystal plasticity constitutive model is developed, which considers damage and strain gradient to reflect the size effect of the creep property. The creep behavior of Nickel-base superalloys with two different precipitate sizes and three different precipitate morphologies are studied. The results show that the model can reflect the size effect on the creep behavior of the alloy very well. At the same time, the precipitate morphologies also have important effects on the mechanical properties of the alloy. With the increase of the slenderness ratio of the precipitate, the creep life of the nickel-base superalloys is extending. This phenomenon indicates that the precipitate coarsening and morphologies influence the creep behavior of the alloy as a competitive mechanism.
2012, Vol. 33 
