A physics-based crystal plasticity model of nickel-based single crystal superalloy for different loading conditions under a wide temperature range

Abstract

Nickel-based single crystal (NBSC) superalloys are extensively used in the fabrication of turbine blades for aero engines, where their deformation behaviours play a critical role in ensuring flight safety. The deformation behaviours are governed by complex micro-scale mechanisms, such as matrix slip, precipitate shearing, interface dislocation pile-up, dislocation climb, coarsening, and rafting. However, many existing models either inadequately account for the underlying deformation mechanisms or rely heavily on temperature-sensitive material parameters, both of which undermine their predictive accuracy and generalizability under diverse loading and thermal conditions. To address these limitations, this study develops a robust and versatile crystal plasticity model that incorporates the above mechanisms. The model decouples temperature effects from constitutive parameters to mitigate parameter sensitivity to temperature variations. Additionally, a parameter decoupling strategy is employed to reduce the number of adjustable parameters and facilitate their identification. The model is validated against experimental data for the DD6 superalloy under uniaxial tension, creep, and low-cycle fatigue tests conducted across a wide temperature range (20–980 °C). The predicted mechanical responses demonstrate good agreement with the experimental results. Finally, the model is applied to simulate the mechanical behaviour of a specimen with inclined cooling holes. The model gives a nearly linear response of creep displacement, which matches well with the experiments.