Healing behaviour of creep induced cavities during hot isostatic pressing of nickel based superalloy

The evolution of morphological characteristics associated with creep induced cavities in a cast polycrystalline superalloy under various hot isostatic pressing conditions was investigated. Concentrically oriented N type γ′ rafting structures near the sintering cavities were formed during sintering. The stress gradient causing a chemical potential gradient around the cavity plays a dominant role in solute diffusion, resulting in the nucleation and continuous growth of the solid solution on the cavity surface to achieve healing.