Cavity Nucleation and Growth in Nickel-Based Alloys during Creep

The number of fossil fueled power plants in electricity generation is still rising, making improvements to their efficiency essential. The development of new materials to withstand the higher service temperatures and pressures of newer, more efficient power plants is greatly aided by physics-based models, which can simulate the microstructural processes leading to their eventual failure. In this work, such a model is developed from classical nucleation theory and diffusion driven growth from vacancy condensation. This model predicts the shape and distribution of cavities which nucleate almost exclusively at grain boundaries during high temperature creep. Cavity radii, number density and phase fraction are validated quantitively against specimens of nickel-based alloys (617 and 625) tested at 700 degrees C and stresses between 160 and 185 MPa. The model's results agree well with the experimental results. However, they fail to represent the complex interlinking of cavities which occurs in tertiary creep.

Automated summary

Physics-based models are helpful in developing new materials for more efficient power plants in fossil fueled electricity generation. This study develops a model based on classical nucleation theory and diffusion driven growth to predict the shape and distribution of cavities that occur mainly at grain boundaries during high temperature creep. The model's results are validated against experimental specimens and show good agreement, although it fails to represent the complex interlinking of cavities during tertiary creep.