Dendrite evolution and quantitative characterization of γ′ precipitates in a powder metallurgy Ni-based superalloy by different cooling rates

The effect of cooling rate after super-solvus heat treatment on the morphological evolution of gamma' precipitates in an advanced powder metallurgy Ni-based superalloy, FGH4113A, was systematically investigated. The quantitative relationship between the cooling rate and gamma' precipitates was elucidated in detail. The results showed that at cooling rates of 200 degrees C/min and 600 degrees C/min, the primary branch of dendritic gamma' grew along the < 111 > direction, whereas the secondary branch grew along the < 100 > and {111} directions. In addition to the interfacial and elastic strain energies, the width of the gamma' channel significantly impacted the evolution of the secondary dendritic orientation of gamma'. As the cooling rate decreased, the size and volume fraction of the gamma' precipitates increased, whereas the nucleation density of the gamma' precipitates decreased. A strong power-law relationship between the characterization of the gamma' precipitates (such as volume fraction, nucleation density, particle size) and the cooling rate was revealed analytically. Meanwhile, the gamma' morphologies evolved from spheres to cuboids, concave cuboids, octets, and dendrites as the cooling rate decreased. The evolution mechanism and stability of gamma' precipitates were proposed to control their morphology and optimize the properties of superalloys. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

The effect of cooling rate after super-solvus heat treatment on the morphological evolution of gamma' precipitates in an advanced powder metallurgy Ni-based superalloy was investigated. The relationship between cooling rate and gamma' precipitates was quantitatively analyzed. The results showed that cooling rate influenced the primary and secondary dendritic orientations of gamma' precipitates. Additionally, the width of the gamma' channel and the cooling rate affected the morphology and evolution of the gamma' precipitates.