Gamma prime formation in nickel-based superalloy IN738LC manufactured by laser powder bed fusion
Journal article, 2024

Complex components for high-temperature gas turbine applications require materials that offer a combination of excellent high-temperature strength and oxidation resistance. Nickel-based superalloys with high gamma prime (γ´) volume fractions are particularly suited for these applications, especially combined with additive manufacturing for intricate geometries. Despite the complex thermal history that these materials experience during laser powder bed fusion (LPBF) processing, γ´formation is suppressed when manufacturing IN738LC, which has a medium equilibrium γ´content of about 40–50 vol%. This study follows γ´formation in LPBF IN738LC during subsequent annealing treatments at temperatures ranging from 745 °C to 865 °C, creating an experimentally determined TTT (temperature-time-transformation) diagram. This diagram is largely based on scanning electron microscopy (SEM) imaging supported by Vickers hardness measurements and scanning transmission electron microscopy (STEM) bright field imaging. Atom probe tomography (APT) of the as-built material indicated nm-sized regions depleted in Cr and enriched in Ni, Al, and Ti, but show no characteristic superlattice patterns in TEM diffraction. APT and TEM diffraction analysis of material annealed at 850 °C for 3 min confirmed the presence of the γ´phase but indicated that γ´had formed through spinodal decomposition instead of precipitation.

IN738LC

Laser powder bed fusion (LPBF)

Gamma prime

Spinodal decomposition

Atom probe tomography (APT)

Author

Fiona Schulz

Bundeswehr University Munich

Chalmers, Industrial and Materials Science, Materials and manufacture

Kristina Lindgren

Chalmers, Physics, Microstructure Physics

Jinghao Xu

Linköping University

Eduard Hryha

Chalmers, Industrial and Materials Science, Materials and manufacture

Materials Today Communications

23524928 (eISSN)

Vol. 38 107905

Subject Categories

Manufacturing, Surface and Joining Technology

Metallurgy and Metallic Materials

Areas of Advance

Materials Science

DOI

10.1016/j.mtcomm.2023.107905

More information

Latest update

3/1/2024 1