École des Mines de Paris
Dynamic precipitation is shown to occur during hot-deformation of a typical γ-γ’ polycrystalline nickel base superalloy. Hot-compression tests at different temperatures and at 10−2 𝑠−1 strain rate and also creep tests were performed below the γ’ solvus temperature, to understand the mechanisms of 𝛾′ precipitation during deformation and the driving forces behind these mechanisms. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) were employed to characterize the different populations of 𝛾′ precipitates and their evolutions, notably through the complex interactions of 𝛾′ precipitates with recrystallization phenomena. The 𝛾′ area fraction observed after hot-compression are systematically higher than the fraction before deformation within the investigated strain level and temperature ranges. Two new populations of precipitates formed during deformation are identified and characterized. Finally, a scenario for dynamic 𝛾′ nucleation, growth and interaction with the recrystallization front are proposed to explain the experimental observations, including also the results of creep tests.
Abstract
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