Nanovoid dynamics based on temperature dependent Young modulus and void formation energy in Nickel: a phase field study

In the present work, a phase field method is used to study the growth/annihilation of nanovoids under thermal and mechanical loadings. To do so, the coupled system of the Cahn-Hilliard and elasticity equations is solved using the nonlinear finite element method in 2D. This coupling is due to the presence of elastic energy in the Cahn-Hilliard free energy and the dependence of total strain on the void misfit strain. The novel point in the present physical model is including the temperature dependence of elastic properties and void formation energy. Then, examples of nanovoid structure evolution are presented consisting of planar gas-solid interface formation and evolution, growth/annihilation of circular nanovoids at different temperatures, growth/annihilation of nanovoids under biaxial compression and at different temperatures and nanovoid structure evolution with initially, randomly distributed void pattern. The obtained results show a faster growth with larger amounts of void concentration at lower temperatures. Also, the stress field significantly varies during nanovoids growth/annihilation especially inside the solid-gas interface and its value depends on the nanovoid size and the concentration